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2019-08-28x86/build: Add -Wnoaddress-of-packed-member to REALMODE_CFLAGS, to silence ↵Linus Torvalds1-0/+1
GCC9 build warning One of the very few warnings I have in the current build comes from arch/x86/boot/edd.c, where I get the following with a gcc9 build: arch/x86/boot/edd.c: In function ‘query_edd’: arch/x86/boot/edd.c:148:11: warning: taking address of packed member of ‘struct boot_params’ may result in an unaligned pointer value [-Waddress-of-packed-member] 148 | mbrptr = boot_params.edd_mbr_sig_buffer; | ^~~~~~~~~~~ This warning triggers because we throw away all the CFLAGS and then make a new set for REALMODE_CFLAGS, so the -Wno-address-of-packed-member we added in the following commit is not present: 6f303d60534c ("gcc-9: silence 'address-of-packed-member' warning") The simplest solution for now is to adjust the warning for this version of CFLAGS as well, but it would definitely make sense to examine whether REALMODE_CFLAGS could be derived from CFLAGS, so that it picks up changes in the compiler flags environment automatically. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Borislav Petkov <bp@alien8.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-04-05x86/build: Keep local relocations with ld.lldKees Cook1-1/+1
The LLVM linker (ld.lld) defaults to removing local relocations, which causes KASLR boot failures. ld.bfd and ld.gold already handle this correctly. This adds the explicit instruction "--discard-none" during the link phase. There is no change in output for ld.bfd and ld.gold, but ld.lld now produces an image with all the needed relocations. Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: clang-built-linux@googlegroups.com Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/20190404214027.GA7324@beast Link: https://github.com/ClangBuiltLinux/linux/issues/404
2019-03-28x86/retpolines: Disable switch jump tables when retpolines are enabledDaniel Borkmann1-2/+6
Commit ce02ef06fcf7 ("x86, retpolines: Raise limit for generating indirect calls from switch-case") raised the limit under retpolines to 20 switch cases where gcc would only then start to emit jump tables, and therefore effectively disabling the emission of slow indirect calls in this area. After this has been brought to attention to gcc folks [0], Martin Liska has then fixed gcc to align with clang by avoiding to generate switch jump tables entirely under retpolines. This is taking effect in gcc starting from stable version 8.4.0. Given kernel supports compilation with older versions of gcc where the fix is not being available or backported anymore, we need to keep the extra KBUILD_CFLAGS around for some time and generally set the -fno-jump-tables to align with what more recent gcc is doing automatically today. More than 20 switch cases are not expected to be fast-path critical, but it would still be good to align with gcc behavior for versions < 8.4.0 in order to have consistency across supported gcc versions. vmlinux size is slightly growing by 0.27% for older gcc. This flag is only set to work around affected gcc, no change for clang. [0] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86952 Suggested-by: Martin Liska <mliska@suse.cz> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Cc: Björn Töpel<bjorn.topel@intel.com> Cc: Magnus Karlsson <magnus.karlsson@intel.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: H.J. Lu <hjl.tools@gmail.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: David S. Miller <davem@davemloft.net> Link: https://lkml.kernel.org/r/20190325135620.14882-1-daniel@iogearbox.net
2019-03-07Merge branch 'x86-fpu-for-linus' of ↵Linus Torvalds1-1/+0
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 fpu updates from Ingo Molnar: "Three changes: - preparatory patch for AVX state tracking that computing-cluster folks would like to use for user-space batching - but we are not happy about the related ABI yet so this is only the kernel tracking side - a cleanup for CR0 handling in do_device_not_available() - plus we removed a workaround for an ancient binutils version" * 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/fpu: Track AVX-512 usage of tasks x86/fpu: Get rid of CONFIG_AS_FXSAVEQ x86/traps: Have read_cr0() only once in the #NM handler
2019-02-28x86, retpolines: Raise limit for generating indirect calls from switch-caseDaniel Borkmann1-0/+5
From networking side, there are numerous attempts to get rid of indirect calls in fast-path wherever feasible in order to avoid the cost of retpolines, for example, just to name a few: * 283c16a2dfd3 ("indirect call wrappers: helpers to speed-up indirect calls of builtin") * aaa5d90b395a ("net: use indirect call wrappers at GRO network layer") * 028e0a476684 ("net: use indirect call wrappers at GRO transport layer") * 356da6d0cde3 ("dma-mapping: bypass indirect calls for dma-direct") * 09772d92cd5a ("bpf: avoid retpoline for lookup/update/delete calls on maps") * 10870dd89e95 ("netfilter: nf_tables: add direct calls for all builtin expressions") [...] Recent work on XDP from Björn and Magnus additionally found that manually transforming the XDP return code switch statement with more than 5 cases into if-else combination would result in a considerable speedup in XDP layer due to avoidance of indirect calls in CONFIG_RETPOLINE enabled builds. On i40e driver with XDP prog attached, a 20-26% speedup has been observed [0]. Aside from XDP, there are many other places later in the networking stack's critical path with similar switch-case processing. Rather than fixing every XDP-enabled driver and locations in stack by hand, it would be good to instead raise the limit where gcc would emit expensive indirect calls from the switch under retpolines and stick with the default as-is in case of !retpoline configured kernels. This would also have the advantage that for archs where this is not necessary, we let compiler select the underlying target optimization for these constructs and avoid potential slow-downs by if-else hand-rewrite. In case of gcc, this setting is controlled by case-values-threshold which has an architecture global default that selects 4 or 5 (latter if target does not have a case insn that compares the bounds) where some arch back ends like arm64 or s390 override it with their own target hooks, for example, in gcc commit db7a90aa0de5 ("S/390: Disable prediction of indirect branches") the threshold pretty much disables jump tables by limit of 20 under retpoline builds. Comparing gcc's and clang's default code generation on x86-64 under O2 level with retpoline build results in the following outcome for 5 switch cases: * gcc with -mindirect-branch=thunk-inline -mindirect-branch-register: # gdb -batch -ex 'disassemble dispatch' ./c-switch Dump of assembler code for function dispatch: 0x0000000000400be0 <+0>: cmp $0x4,%edi 0x0000000000400be3 <+3>: ja 0x400c35 <dispatch+85> 0x0000000000400be5 <+5>: lea 0x915f8(%rip),%rdx # 0x4921e4 0x0000000000400bec <+12>: mov %edi,%edi 0x0000000000400bee <+14>: movslq (%rdx,%rdi,4),%rax 0x0000000000400bf2 <+18>: add %rdx,%rax 0x0000000000400bf5 <+21>: callq 0x400c01 <dispatch+33> 0x0000000000400bfa <+26>: pause 0x0000000000400bfc <+28>: lfence 0x0000000000400bff <+31>: jmp 0x400bfa <dispatch+26> 0x0000000000400c01 <+33>: mov %rax,(%rsp) 0x0000000000400c05 <+37>: retq 0x0000000000400c06 <+38>: nopw %cs:0x0(%rax,%rax,1) 0x0000000000400c10 <+48>: jmpq 0x400c90 <fn_3> 0x0000000000400c15 <+53>: nopl (%rax) 0x0000000000400c18 <+56>: jmpq 0x400c70 <fn_2> 0x0000000000400c1d <+61>: nopl (%rax) 0x0000000000400c20 <+64>: jmpq 0x400c50 <fn_1> 0x0000000000400c25 <+69>: nopl (%rax) 0x0000000000400c28 <+72>: jmpq 0x400c40 <fn_0> 0x0000000000400c2d <+77>: nopl (%rax) 0x0000000000400c30 <+80>: jmpq 0x400cb0 <fn_4> 0x0000000000400c35 <+85>: push %rax 0x0000000000400c36 <+86>: callq 0x40dd80 <abort> End of assembler dump. * clang with -mretpoline emitting search tree: # gdb -batch -ex 'disassemble dispatch' ./c-switch Dump of assembler code for function dispatch: 0x0000000000400b30 <+0>: cmp $0x1,%edi 0x0000000000400b33 <+3>: jle 0x400b44 <dispatch+20> 0x0000000000400b35 <+5>: cmp $0x2,%edi 0x0000000000400b38 <+8>: je 0x400b4d <dispatch+29> 0x0000000000400b3a <+10>: cmp $0x3,%edi 0x0000000000400b3d <+13>: jne 0x400b52 <dispatch+34> 0x0000000000400b3f <+15>: jmpq 0x400c50 <fn_3> 0x0000000000400b44 <+20>: test %edi,%edi 0x0000000000400b46 <+22>: jne 0x400b5c <dispatch+44> 0x0000000000400b48 <+24>: jmpq 0x400c20 <fn_0> 0x0000000000400b4d <+29>: jmpq 0x400c40 <fn_2> 0x0000000000400b52 <+34>: cmp $0x4,%edi 0x0000000000400b55 <+37>: jne 0x400b66 <dispatch+54> 0x0000000000400b57 <+39>: jmpq 0x400c60 <fn_4> 0x0000000000400b5c <+44>: cmp $0x1,%edi 0x0000000000400b5f <+47>: jne 0x400b66 <dispatch+54> 0x0000000000400b61 <+49>: jmpq 0x400c30 <fn_1> 0x0000000000400b66 <+54>: push %rax 0x0000000000400b67 <+55>: callq 0x40dd20 <abort> End of assembler dump. For sake of comparison, clang without -mretpoline: # gdb -batch -ex 'disassemble dispatch' ./c-switch Dump of assembler code for function dispatch: 0x0000000000400b30 <+0>: cmp $0x4,%edi 0x0000000000400b33 <+3>: ja 0x400b57 <dispatch+39> 0x0000000000400b35 <+5>: mov %edi,%eax 0x0000000000400b37 <+7>: jmpq *0x492148(,%rax,8) 0x0000000000400b3e <+14>: jmpq 0x400bf0 <fn_0> 0x0000000000400b43 <+19>: jmpq 0x400c30 <fn_4> 0x0000000000400b48 <+24>: jmpq 0x400c10 <fn_2> 0x0000000000400b4d <+29>: jmpq 0x400c20 <fn_3> 0x0000000000400b52 <+34>: jmpq 0x400c00 <fn_1> 0x0000000000400b57 <+39>: push %rax 0x0000000000400b58 <+40>: callq 0x40dcf0 <abort> End of assembler dump. Raising the cases to a high number (e.g. 100) will still result in similar code generation pattern with clang and gcc as above, in other words clang generally turns off jump table emission by having an extra expansion pass under retpoline build to turn indirectbr instructions from their IR into switch instructions as a built-in -mno-jump-table lowering of a switch (in this case, even if IR input already contained an indirect branch). For gcc, adding --param=case-values-threshold=20 as in similar fashion as s390 in order to raise the limit for x86 retpoline enabled builds results in a small vmlinux size increase of only 0.13% (before=18,027,528 after=18,051,192). For clang this option is ignored due to i) not being needed as mentioned and ii) not having above cmdline parameter. Non-retpoline-enabled builds with gcc continue to use the default case-values-threshold setting, so nothing changes here. [0] https://lore.kernel.org/netdev/20190129095754.9390-1-bjorn.topel@gmail.com/ and "The Path to DPDK Speeds for AF_XDP", LPC 2018, networking track: - http://vger.kernel.org/lpc_net2018_talks/lpc18_pres_af_xdp_perf-v3.pdf - http://vger.kernel.org/lpc_net2018_talks/lpc18_paper_af_xdp_perf-v2.pdf Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Jesper Dangaard Brouer <brouer@redhat.com> Acked-by: Björn Töpel <bjorn.topel@intel.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: netdev@vger.kernel.org Cc: David S. Miller <davem@davemloft.net> Cc: Magnus Karlsson <magnus.karlsson@intel.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Link: https://lkml.kernel.org/r/20190221221941.29358-1-daniel@iogearbox.net
2019-01-22x86/fpu: Get rid of CONFIG_AS_FXSAVEQBorislav Petkov1-1/+0
This was a "workaround" to probe for binutils which could generate FXSAVEQ, apparently gas with min version 2.16. In the meantime, minimal required gas version is 2.20 so all those workarounds for older binutils can be dropped. Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20190117232408.GH5023@zn.tnic
2019-01-06jump_label: move 'asm goto' support test to KconfigMasahiro Yamada1-1/+1
Currently, CONFIG_JUMP_LABEL just means "I _want_ to use jump label". The jump label is controlled by HAVE_JUMP_LABEL, which is defined like this: #if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL) # define HAVE_JUMP_LABEL #endif We can improve this by testing 'asm goto' support in Kconfig, then make JUMP_LABEL depend on CC_HAS_ASM_GOTO. Ugly #ifdef HAVE_JUMP_LABEL will go away, and CONFIG_JUMP_LABEL will match to the real kernel capability. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
2018-12-26Merge branch 'x86-build-for-linus' of ↵Linus Torvalds1-4/+0
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 build updates from Ingo Molnar: - Resolve LLVM build bug by removing redundant GNU specific flag - Remove obsolete -funit-at-a-time and -fno-unit-at-a-time use from x86 PowerPC and UM. The UML change was seen and acked by UML maintainer Richard Weinberger. * 'x86-build-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/um/vdso: Drop implicit common-page-size linker flag x86, powerpc: Remove -funit-at-a-time compiler option entirely x86/um: Remove -fno-unit-at-a-time workaround for pre-4.0 GCC
2018-12-19Revert "kbuild/Makefile: Prepare for using macros in inline assembly code to ↵Ingo Molnar1-7/+0
work around asm() related GCC inlining bugs" This reverts commit 77b0bf55bc675233d22cd5df97605d516d64525e. See this commit for details about the revert: e769742d3584 ("Revert "x86/jump-labels: Macrofy inline assembly code to work around GCC inlining bugs"") Conflicts: arch/x86/Makefile Reported-by: Masahiro Yamada <yamada.masahiro@socionext.com> Reviewed-by: Borislav Petkov <bp@alien8.de> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Juergen Gross <jgross@suse.com> Cc: Richard Biener <rguenther@suse.de> Cc: Kees Cook <keescook@chromium.org> Cc: Segher Boessenkool <segher@kernel.crashing.org> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Nadav Amit <namit@vmware.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-12-09x86, powerpc: Remove -funit-at-a-time compiler option entirelyMasahiro Yamada1-4/+0
GCC 4.6 manual says: -funit-at-a-time This option is left for compatibility reasons. -funit-at-a-time has no effect, while -fno-unit-at-a-time implies -fno-toplevel-reorder and -fno-section-anchors. Enabled by default. Remove it. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Ingo Molnar <mingo@kernel.org> Acked-by: Michael Ellerman <mpe@ellerman.id.au> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Richard Weinberger <richard@sigma-star.at> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linuxppc-dev@lists.ozlabs.org Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/1541990120-9643-3-git-send-email-yamada.masahiro@socionext.com
2018-12-05x86/build: Fix compiler support check for CONFIG_RETPOLINEMasahiro Yamada1-3/+7
It is troublesome to add a diagnostic like this to the Makefile parse stage because the top-level Makefile could be parsed with a stale include/config/auto.conf. Once you are hit by the error about non-retpoline compiler, the compilation still breaks even after disabling CONFIG_RETPOLINE. The easiest fix is to move this check to the "archprepare" like this commit did: 829fe4aa9ac1 ("x86: Allow generating user-space headers without a compiler") Reported-by: Meelis Roos <mroos@linux.ee> Tested-by: Meelis Roos <mroos@linux.ee> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Zhenzhong Duan <zhenzhong.duan@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Zhenzhong Duan <zhenzhong.duan@oracle.com> Fixes: 4cd24de3a098 ("x86/retpoline: Make CONFIG_RETPOLINE depend on compiler support") Link: http://lkml.kernel.org/r/1543991239-18476-1-git-send-email-yamada.masahiro@socionext.com Link: https://lkml.org/lkml/2018/12/4/206 Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-11-28x86/retpoline: Make CONFIG_RETPOLINE depend on compiler supportZhenzhong Duan1-2/+3
Since retpoline capable compilers are widely available, make CONFIG_RETPOLINE hard depend on the compiler capability. Break the build when CONFIG_RETPOLINE is enabled and the compiler does not support it. Emit an error message in that case: "arch/x86/Makefile:226: *** You are building kernel with non-retpoline compiler, please update your compiler.. Stop." [dwmw: Fail the build with non-retpoline compiler] Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: David Woodhouse <dwmw@amazon.co.uk> Cc: Borislav Petkov <bp@suse.de> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Michal Marek <michal.lkml@markovi.net> Cc: <srinivas.eeda@oracle.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/cca0cb20-f9e2-4094-840b-fb0f8810cd34@default
2018-11-05x86/build: Remove -pipe from KBUILD_CFLAGSNathan Chancellor1-3/+1
Commit 77b0bf55bc67 ("kbuild/Makefile: Prepare for using macros in inline assembly code to work around asm() related GCC inlining bugs") added -Wa,- to KBUILD_CFLAGS, which breaks compiling with Clang (hangs indefinitely at compiling init/main.o). This happens because while Clang accepts -pipe (and has it documented in its list of supported flags), it silently ignores it after this 2010 commit (thanks to Nick Desaulniers for tracking this down), meaning that gas just infinitely waits for stdin and never receives it. https://github.com/llvm-mirror/clang/commit/c19a12dc3d441bec62eed55e312b76c12d6d9022 Initially, I had suggested just add -Wa,- to KBUILD_CFLAGS when GCC was being used but that was before realizing it is because Clang doesn't do anything with -pipe. H. Peter Anvin suggested checking to see if -pipe gives us any gains out of GCC. Turns out it might actually be hurting: With -pipe: real 3m40.813s real 3m44.449s real 3m39.648s Without -pipe: real 3m38.492s real 3m38.335s real 3m38.975s The issue of -Wa,- being passed along to gas without -pipe being supported should still probably be fixed on the LLVM side (open issue: https://bugs.llvm.org/show_bug.cgi?id=39410) but this is not as much of a workaround anymore since it helps both GCC and Clang. Suggested-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nadav Amit <namit@vmware.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Link: https://github.com/ClangBuiltLinux/linux/issues/213 Link: https://lkml.kernel.org/r/20181023231125.27976-1-natechancellor@gmail.com
2018-10-04kbuild/Makefile: Prepare for using macros in inline assembly code to work ↵Nadav Amit1-0/+7
around asm() related GCC inlining bugs Using macros in inline assembly allows us to work around bugs in GCC's inlining decisions. Compile macros.S and use it to assemble all C files. Currently only x86 will use it. Background: The inlining pass of GCC doesn't include an assembler, so it's not aware of basic properties of the generated code, such as its size in bytes, or that there are such things as discontiuous blocks of code and data due to the newfangled linker feature called 'sections' ... Instead GCC uses a lazy and fragile heuristic: it does a linear count of certain syntactic and whitespace elements in inlined assembly block source code, such as a count of new-lines and semicolons (!), as a poor substitute for "code size and complexity". Unsurprisingly this heuristic falls over and breaks its neck whith certain common types of kernel code that use inline assembly, such as the frequent practice of putting useful information into alternative sections. As a result of this fresh, 20+ years old GCC bug, GCC's inlining decisions are effectively disabled for inlined functions that make use of such asm() blocks, because GCC thinks those sections of code are "large" - when in reality they are often result in just a very low number of machine instructions. This absolute lack of inlining provess when GCC comes across such asm() blocks both increases generated kernel code size and causes performance overhead, which is particularly noticeable on paravirt kernels, which make frequent use of these inlining facilities in attempt to stay out of the way when running on baremetal hardware. Instead of fixing the compiler we use a workaround: we set an assembly macro and call it from the inlined assembly block. As a result GCC considers the inline assembly block as a single instruction. (Which it often isn't but I digress.) This uglifies and bloats the source code - for example just the refcount related changes have this impact: Makefile | 9 +++++++-- arch/x86/Makefile | 7 +++++++ arch/x86/kernel/macros.S | 7 +++++++ scripts/Kbuild.include | 4 +++- scripts/mod/Makefile | 2 ++ 5 files changed, 26 insertions(+), 3 deletions(-) Yay readability and maintainability, it's not like assembly code is hard to read and maintain ... We also hope that GCC will eventually get fixed, but we are not holding our breath for that. Yet we are optimistic, it might still happen, any decade now. [ mingo: Wrote new changelog describing the background. ] Tested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Nadav Amit <namit@vmware.com> Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <michal.lkml@markovi.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kbuild@vger.kernel.org Link: http://lkml.kernel.org/r/20181003213100.189959-3-namit@vmware.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-10-01x86/build: Remove unused CONFIG_AS_CRC32Masahiro Yamada1-1/+0
CONFIG_AS_CRC32 is not used anywhere. Its last user was removed by 0cb6c969ed9d ("net, lib: kill arch_fast_hash library bits") Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Link: https://lkml.kernel.org/r/1538389443-28514-1-git-send-email-yamada.masahiro@socionext.com
2018-08-31x86: Allow generating user-space headers without a compilerBen Hutchings1-4/+7
When bootstrapping an architecture, it's usual to generate the kernel's user-space headers (make headers_install) before building a compiler. Move the compiler check (for asm goto support) to the archprepare target so that it is only done when building code for the target. Fixes: e501ce957a78 ("x86: Force asm-goto") Reported-by: Helmut Grohne <helmutg@debian.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20180829194317.GA4765@decadent.org.uk
2018-08-30x86/build: Remove jump label quirk for GCC older than 4.5.2Masahiro Yamada1-12/+0
Commit cafa0010cd51 ("Raise the minimum required gcc version to 4.6") bumped the minimum GCC version to 4.6 for all architectures. Remove the workaround code. It was the only user of cc-if-fullversion. Remove the macro as well. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Michal Marek <michal.lkml@markovi.net> Cc: linux-kbuild@vger.kernel.org Link: https://lkml.kernel.org/r/1535348714-25457-1-git-send-email-yamada.masahiro@socionext.com
2018-08-24kbuild: rename LDFLAGS to KBUILD_LDFLAGSMasahiro Yamada1-2/+2
Commit a0f97e06a43c ("kbuild: enable 'make CFLAGS=...' to add additional options to CC") renamed CFLAGS to KBUILD_CFLAGS. Commit 222d394d30e7 ("kbuild: enable 'make AFLAGS=...' to add additional options to AS") renamed AFLAGS to KBUILD_AFLAGS. Commit 06c5040cdb13 ("kbuild: enable 'make CPPFLAGS=...' to add additional options to CPP") renamed CPPFLAGS to KBUILD_CPPFLAGS. For some reason, LDFLAGS was not renamed. Using a well-known variable like LDFLAGS may result in accidental override of the variable. Kbuild generally uses KBUILD_ prefixed variables for the internally appended options, so here is one more conversion to sanitize the naming convention. I did not touch Makefiles under tools/ since the tools build system is a different world. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
2018-07-16x86/build: Remove old -funit-at-a-time GCC quirkMasahiro Yamada1-5/+0
The following commit: e501ce957a78 ("x86: Force asm-goto") ... bumped the minimum GCC version to 4.5 for building the x86 kernel. arch/x86/Makefile no longer needs to take care of older GCC versions, such as this pre-4.0 -funit-at-a-time quirk. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Link: http://lkml.kernel.org/r/1531138041-24200-1-git-send-email-yamada.masahiro@socionext.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-06-22Merge branch 'linus' into x86/urgentThomas Gleixner1-1/+1
Required to queue a dependent fix.
2018-06-21x86/build: Remove unnecessary preparation for purgatoryMasahiro Yamada1-5/+0
kexec-purgatory.c is properly generated when Kbuild descend into the arch/x86/purgatory/. Thus the 'archprepare' target is redundant. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <michal.lkml@markovi.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/lkml/1529401422-28838-3-git-send-email-yamada.masahiro@socionext.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-06-21Revert "kexec/purgatory: Add clean-up for purgatory directory"Masahiro Yamada1-1/+0
Reverts the following commit: b0108f9e93d0 ("kexec: purgatory: add clean-up for purgatory directory") ... which incorrectly stated that the kexec-purgatory.c and purgatory.ro files were not removed after 'make mrproper'. In fact, they are. You can confirm it after reverting it. $ make mrproper $ touch arch/x86/purgatory/kexec-purgatory.c $ touch arch/x86/purgatory/purgatory.ro $ make mrproper CLEAN arch/x86/purgatory $ ls arch/x86/purgatory/ entry64.S Makefile purgatory.c setup-x86_64.S stack.S string.c This is obvious from the build system point of view. arch/x86/Makefile adds 'arch/x86' to core-y. Hence 'make clean' descends like this: arch/x86/Kbuild -> arch/x86/purgatory/Makefile Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <michal.lkml@markovi.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/lkml/1529401422-28838-2-git-send-email-yamada.masahiro@socionext.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-06-01kbuild: add machine size to CHECKFLAGSLuc Van Oostenryck1-1/+1
By default, sparse assumes a 64bit machine when compiled on x86-64 and 32bit when compiled on anything else. This can of course create all sort of problems for the other archs, like issuing false warnings ('shift too big (32) for type unsigned long'), or worse, failing to emit legitimate warnings. Fix this by adding the -m32/-m64 flag, depending on CONFIG_64BIT, to CHECKFLAGS in the main Makefile (and so for all archs). Also, remove the now unneeded -m32/-m64 in arch specific Makefiles. Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-04-02Merge branch 'x86-build-for-linus' of ↵Linus Torvalds1-2/+5
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 build updates from Ingo Molnar: "The biggest change is the forcing of asm-goto support on x86, which effectively increases the GCC minimum supported version to gcc-4.5 (on x86)" * 'x86-build-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/build: Don't pass in -D__KERNEL__ multiple times x86: Remove FAST_FEATURE_TESTS x86: Force asm-goto x86/build: Drop superfluous ALIGN from the linker script
2018-03-31x86/build: Don't pass in -D__KERNEL__ multiple timesCao jin1-2/+1
Some .<target>.cmd files under arch/x86 are showing two instances of -D__KERNEL__, like arch/x86/boot/ and arch/x86/realmode/rm/. __KERNEL__ is already defined in KBUILD_CPPFLAGS in the top Makefile, so it can be dropped safely. Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Michal Marek <michal.lkml@markovi.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kbuild@vger.kernel.org Link: http://lkml.kernel.org/r/20180316084944.3997-1-caoj.fnst@cn.fujitsu.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-20x86: Force asm-gotoPeter Zijlstra1-0/+4
We want to start using asm-goto to guarantee the absence of dynamic branches (and thus speculation). A primary prerequisite for this is of course that the compiler supports asm-goto. This effecively lifts the minimum GCC version to build an x86 kernel to gcc-4.5. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: torvalds@linux-foundation.org Link: https://lkml.kernel.org/r/20180319201327.GJ4043@hirez.programming.kicks-ass.net
2018-03-20x86/build/64: Force the linker to use 2MB page sizeH.J. Lu1-0/+9
Binutils 2.31 will enable -z separate-code by default for x86 to avoid mixing code pages with data to improve cache performance as well as security. To reduce x86-64 executable and shared object sizes, the maximum page size is reduced from 2MB to 4KB. But x86-64 kernel must be aligned to 2MB. Pass -z max-page-size=0x200000 to linker to force 2MB page size regardless of the default page size used by linker. Tested with Linux kernel 4.15.6 on x86-64. Signed-off-by: H.J. Lu <hjl.tools@gmail.com> Cc: Andy Shevchenko <andy.shevchenko@gmail.com> Cc: Eric Biederman <ebiederm@xmission.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Juergen Gross <jgross@suse.com> Cc: Kees Cook <keescook@chromium.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/CAMe9rOp4_%3D_8twdpTyAP2DhONOCeaTOsniJLoppzhoNptL8xzA@mail.gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-02-21objtool, retpolines: Integrate objtool with retpoline support more closelyPeter Zijlstra1-7/+3
Disable retpoline validation in objtool if your compiler sucks, and otherwise select the validation stuff for CONFIG_RETPOLINE=y (most builds would already have it set due to ORC). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-02-20x86/retpoline: Support retpoline builds with ClangDavid Woodhouse1-1/+4
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: arjan.van.de.ven@intel.com Cc: bp@alien8.de Cc: dave.hansen@intel.com Cc: jmattson@google.com Cc: karahmed@amazon.de Cc: kvm@vger.kernel.org Cc: pbonzini@redhat.com Cc: rkrcmar@redhat.com Link: http://lkml.kernel.org/r/1519037457-7643-5-git-send-email-dwmw@amazon.co.uk Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-01-14Merge branch 'x86-pti-for-linus' of ↵Linus Torvalds1-2/+0
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 fixlet from Thomas Gleixner. Remove a warning about lack of compiler support for retpoline that most people can't do anything about, so it just annoys them needlessly. * 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/retpoline: Remove compile time warning
2018-01-14x86/retpoline: Remove compile time warningThomas Gleixner1-2/+0
Remove the compile time warning when CONFIG_RETPOLINE=y and the compiler does not have retpoline support. Linus rationale for this is: It's wrong because it will just make people turn off RETPOLINE, and the asm updates - and return stack clearing - that are independent of the compiler are likely the most important parts because they are likely the ones easiest to target. And it's annoying because most people won't be able to do anything about it. The number of people building their own compiler? Very small. So if their distro hasn't got a compiler yet (and pretty much nobody does), the warning is just annoying crap. It is already properly reported as part of the sysfs interface. The compile-time warning only encourages bad things. Fixes: 76b043848fd2 ("x86/retpoline: Add initial retpoline support") Requested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: David Woodhouse <dwmw@amazon.co.uk> Cc: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: gnomes@lxorguk.ukuu.org.uk Cc: Rik van Riel <riel@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: thomas.lendacky@amd.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Jiri Kosina <jikos@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Kees Cook <keescook@google.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Greg Kroah-Hartman <gregkh@linux-foundation.org> Link: https://lkml.kernel.org/r/CA+55aFzWgquv4i6Mab6bASqYXg3ErV3XDFEYf=GEcCDQg5uAtw@mail.gmail.com
2018-01-14Merge branch 'x86-pti-for-linus' of ↵Linus Torvalds1-0/+10
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 pti updates from Thomas Gleixner: "This contains: - a PTI bugfix to avoid setting reserved CR3 bits when PCID is disabled. This seems to cause issues on a virtual machine at least and is incorrect according to the AMD manual. - a PTI bugfix which disables the perf BTS facility if PTI is enabled. The BTS AUX buffer is not globally visible and causes the CPU to fault when the mapping disappears on switching CR3 to user space. A full fix which restores BTS on PTI is non trivial and will be worked on. - PTI bugfixes for EFI and trusted boot which make sure that the user space visible page table entries have the NX bit cleared - removal of dead code in the PTI pagetable setup functions - add PTI documentation - add a selftest for vsyscall to verify that the kernel actually implements what it advertises. - a sysfs interface to expose vulnerability and mitigation information so there is a coherent way for users to retrieve the status. - the initial spectre_v2 mitigations, aka retpoline: + The necessary ASM thunk and compiler support + The ASM variants of retpoline and the conversion of affected ASM code + Make LFENCE serializing on AMD so it can be used as speculation trap + The RSB fill after vmexit - initial objtool support for retpoline As I said in the status mail this is the most of the set of patches which should go into 4.15 except two straight forward patches still on hold: - the retpoline add on of LFENCE which waits for ACKs - the RSB fill after context switch Both should be ready to go early next week and with that we'll have covered the major holes of spectre_v2 and go back to normality" * 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (28 commits) x86,perf: Disable intel_bts when PTI security/Kconfig: Correct the Documentation reference for PTI x86/pti: Fix !PCID and sanitize defines selftests/x86: Add test_vsyscall x86/retpoline: Fill return stack buffer on vmexit x86/retpoline/irq32: Convert assembler indirect jumps x86/retpoline/checksum32: Convert assembler indirect jumps x86/retpoline/xen: Convert Xen hypercall indirect jumps x86/retpoline/hyperv: Convert assembler indirect jumps x86/retpoline/ftrace: Convert ftrace assembler indirect jumps x86/retpoline/entry: Convert entry assembler indirect jumps x86/retpoline/crypto: Convert crypto assembler indirect jumps x86/spectre: Add boot time option to select Spectre v2 mitigation x86/retpoline: Add initial retpoline support objtool: Allow alternatives to be ignored objtool: Detect jumps to retpoline thunks x86/pti: Make unpoison of pgd for trusted boot work for real x86/alternatives: Fix optimize_nops() checking sysfs/cpu: Fix typos in vulnerability documentation x86/cpu/AMD: Use LFENCE_RDTSC in preference to MFENCE_RDTSC ...
2018-01-12x86/retpoline: Add initial retpoline supportDavid Woodhouse1-0/+10
Enable the use of -mindirect-branch=thunk-extern in newer GCC, and provide the corresponding thunks. Provide assembler macros for invoking the thunks in the same way that GCC does, from native and inline assembler. This adds X86_FEATURE_RETPOLINE and sets it by default on all CPUs. In some circumstances, IBRS microcode features may be used instead, and the retpoline can be disabled. On AMD CPUs if lfence is serialising, the retpoline can be dramatically simplified to a simple "lfence; jmp *\reg". A future patch, after it has been verified that lfence really is serialising in all circumstances, can enable this by setting the X86_FEATURE_RETPOLINE_AMD feature bit in addition to X86_FEATURE_RETPOLINE. Do not align the retpoline in the altinstr section, because there is no guarantee that it stays aligned when it's copied over the oldinstr during alternative patching. [ Andi Kleen: Rename the macros, add CONFIG_RETPOLINE option, export thunks] [ tglx: Put actual function CALL/JMP in front of the macros, convert to symbolic labels ] [ dwmw2: Convert back to numeric labels, merge objtool fixes ] Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Arjan van de Ven <arjan@linux.intel.com> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: gnomes@lxorguk.ukuu.org.uk Cc: Rik van Riel <riel@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: thomas.lendacky@amd.com Cc: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Jiri Kosina <jikos@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Kees Cook <keescook@google.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Greg Kroah-Hartman <gregkh@linux-foundation.org> Cc: Paul Turner <pjt@google.com> Link: https://lkml.kernel.org/r/1515707194-20531-4-git-send-email-dwmw@amazon.co.uk
2017-11-15kmemcheck: remove annotationsLevin, Alexander (Sasha Levin)1-5/+0
Patch series "kmemcheck: kill kmemcheck", v2. As discussed at LSF/MM, kill kmemcheck. KASan is a replacement that is able to work without the limitation of kmemcheck (single CPU, slow). KASan is already upstream. We are also not aware of any users of kmemcheck (or users who don't consider KASan as a suitable replacement). The only objection was that since KASAN wasn't supported by all GCC versions provided by distros at that time we should hold off for 2 years, and try again. Now that 2 years have passed, and all distros provide gcc that supports KASAN, kill kmemcheck again for the very same reasons. This patch (of 4): Remove kmemcheck annotations, and calls to kmemcheck from the kernel. [alexander.levin@verizon.com: correctly remove kmemcheck call from dma_map_sg_attrs] Link: http://lkml.kernel.org/r/20171012192151.26531-1-alexander.levin@verizon.com Link: http://lkml.kernel.org/r/20171007030159.22241-2-alexander.levin@verizon.com Signed-off-by: Sasha Levin <alexander.levin@verizon.com> Cc: Alexander Potapenko <glider@google.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Tim Hansen <devtimhansen@gmail.com> Cc: Vegard Nossum <vegardno@ifi.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-02License cleanup: add SPDX GPL-2.0 license identifier to files with no licenseGreg Kroah-Hartman1-0/+1
Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-08-21x86/build: Use cc-option to validate stack alignment parameterMatthias Kaehlcke1-3/+3
With the following commit: 8f91869766c0 ("x86/build: Fix stack alignment for CLang") cc-option is only used to determine the name of the stack alignment option supported by the compiler, but not to verify that the actual parameter <option>=N is valid in combination with the other CFLAGS. This causes problems (as reported by the kbuild robot) with older GCC versions which only support stack alignment on a boundary of 16 bytes or higher. Also use (__)cc_option to add the stack alignment option to CFLAGS to make sure only valid options are added. Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Matthias Kaehlcke <mka@chromium.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Bernhard.Rosenkranzer@linaro.org Cc: Greg Hackmann <ghackmann@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Michael Davidson <md@google.com> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephen Hines <srhines@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: dianders@chromium.org Fixes: 8f91869766c0 ("x86/build: Fix stack alignment for CLang") Link: http://lkml.kernel.org/r/20170817182047.176752-1-mka@chromium.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-17x86/build: Fix stack alignment for CLangMatthias Kaehlcke1-6/+8
Commit: d77698df39a5 ("x86/build: Specify stack alignment for clang") intended to use the same stack alignment for clang as with gcc. The two compilers use different options to configure the stack alignment (gcc: -mpreferred-stack-boundary=n, clang: -mstack-alignment=n). The above commit assumes that the clang option uses the same parameter type as gcc, i.e. that the alignment is specified as 2^n. However clang interprets the value of this option literally to use an alignment of n, in consequence the stack remains misaligned. Change the values used with -mstack-alignment to be the actual alignment instead of a power of two. cc-option isn't used here with the typical pattern of KBUILD_CFLAGS += $(call cc-option ...). The reason is that older gcc versions don't support the -mpreferred-stack-boundary option, since cc-option doesn't verify whether the alternative option is valid it would incorrectly select the clang option -mstack-alignment.. Signed-off-by: Matthias Kaehlcke <mka@chromium.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Bernhard.Rosenkranzer@linaro.org Cc: Greg Hackmann <ghackmann@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Michael Davidson <md@google.com> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephen Hines <srhines@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: dianders@chromium.org Link: http://lkml.kernel.org/r/20170817004740.170588-1-mka@chromium.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-10x86/build: Drop unused mflags-yCao jin1-3/+0
Subarchitecture support (mflags-y) was removed from x86 in this commit: 6bda2c8b32fe ("x86: remove subarchitecture support") So drop the mflags-y usage from the Makefile. Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1502105384-23214-1-git-send-email-caoj.fnst@cn.fujitsu.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-07Merge tag 'kbuild-v4.13' of ↵Linus Torvalds1-8/+25
git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild Pull Kbuild updates from Masahiro Yamada: - Clean up Makefiles and scripts - Improve clang support - Remove unneeded genhdr-y syntax - Remove unneeded cc-option-align macro - Introduce __cc-option macro and use it to fix x86 boot code compiler flags * tag 'kbuild-v4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: kbuild: improve comments on KBUILD_SRC x86/build: Specify stack alignment for clang x86/build: Use __cc-option for boot code compiler options kbuild: Add __cc-option macro kbuild: remove cc-option-align kbuild: replace genhdr-y with generated-y kbuild: clang: Disable 'address-of-packed-member' warning kbuild: remove duplicated arch/*/include/generated/uapi include path kbuild: speed up checksyscalls.sh kbuild: simplify silent build (-s) detection
2017-06-25x86/build: Specify stack alignment for clangMatthias Kaehlcke1-5/+21
For gcc stack alignment is configured with -mpreferred-stack-boundary=N, clang has the option -mstack-alignment=N for that purpose. Use the same alignment as with gcc. If the alignment is not specified clang assumes an alignment of 16 bytes, as required by the standard ABI. However as mentioned in d9b0cde91c60 ("x86-64, gcc: Use -mpreferred-stack-boundary=3 if supported") the standard kernel entry on x86-64 leaves the stack on an 8-byte boundary, as a consequence clang will keep the stack misaligned. Signed-off-by: Matthias Kaehlcke <mka@chromium.org> Acked-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2017-06-25x86/build: Use __cc-option for boot code compiler optionsMatthias Kaehlcke1-4/+5
cc-option is used to enable compiler options for the boot code if they are available. The macro uses KBUILD_CFLAGS and KBUILD_CPPFLAGS for the check, however these flags aren't used to build the boot code, in consequence cc-option can yield wrong results. For example -mpreferred-stack-boundary=2 is never set with a 64-bit compiler, since the setting is only valid for 16 and 32-bit binaries. This is also the case for 32-bit kernel builds, because the option -m32 is added to KBUILD_CFLAGS after the assignment of REALMODE_CFLAGS. Use __cc-option instead of cc-option for the boot mode options. The macro receives the compiler options as parameter instead of using KBUILD_C*FLAGS, for the boot code we pass REALMODE_CFLAGS. Also use separate statements for the __cc-option checks instead of performing them in the initial assignment of REALMODE_CFLAGS since the variable is an input of the macro. Signed-off-by: Matthias Kaehlcke <mka@chromium.org> Acked-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2017-06-14x86/mce: Merge mce_amd_inj into mce-injectBorislav Petkov1-2/+0
Reuse mce_amd_inj's debugfs interface so that mce-inject can benefit from it too. The old functionality is still preserved under CONFIG_X86_MCELOG_LEGACY. Tested-by: Yazen Ghannam <yazen.ghannam@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Yazen Ghannam <yazen.ghannam@amd.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Link: http://lkml.kernel.org/r/20170613162835.30750-4-bp@alien8.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-05-24x86/build: Permit building with old make versionsJan Kiszka1-1/+1
At least Make 3.82 dislikes the tab in front of the $(warning) function: arch/x86/Makefile:162: *** recipe commences before first target. Stop. Let's be gentle. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1944fcd8-e3df-d1f7-c0e4-60aeb1917a24@siemens.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-05-09x86/build: Don't add -maccumulate-outgoing-args w/o compiler supportNick Desaulniers1-1/+2
Clang does not support this machine dependent option. Older versions of GCC (pre 3.0) may not support this option, added in 2000, but it's unlikely they can still compile a working kernel. Signed-off-by: Nick Desaulniers <nick.desaulniers@gmail.com> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20170509032946.20444-1-nick.desaulniers@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-05-01Merge branch 'x86-build-for-linus' of ↵Linus Torvalds1-2/+2
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 build update from Ingo Molnar: "A single CLang support related fix" * 'x86-build-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/kbuild: Use cc-option to enable -falign-{jumps/loops}
2017-04-19x86/build: convert function graph '-Os' error to warningJosh Poimboeuf1-0/+8
For pre-4.6.0 versions of GCC, which don't have '-mfentry', the '-maccumulate-outgoing-args' option is required for function graph tracing in order to avoid GCC bug 42109. However, GCC ignores '-maccumulate-outgoing-args' when '-Os' is also set. Currently we force a build error to prevent that scenario, but that breaks randconfigs. So change the error to a warning which also disables CONFIG_CC_OPTIMIZE_FOR_SIZE. Reported-by: Andi Kleen <andi@firstfloor.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: kbuild test robot <fengguang.wu@intel.com> Cc: kbuild-all@01.org Link: http://lkml.kernel.org/r/20170418214429.o7fbwbmf4nqosezy@treble Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-04-17x86/kbuild: Use cc-option to enable -falign-{jumps/loops}Matthias Kaehlcke1-2/+2
clang currently does not support these optimizations, only enable them when they are available. Signed-off-by: Matthias Kaehlcke <mka@chromium.org> Cc: Greg Hackmann <ghackmann@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Michael Davidson <md@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: grundler@chromium.org Link: http://lkml.kernel.org/r/20170413172609.118122-1-mka@chromium.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-30x86/build: Mostly disable '-maccumulate-outgoing-args'Josh Poimboeuf1-4/+31
The GCC '-maccumulate-outgoing-args' flag is enabled for most configs, mostly because of issues which are no longer relevant. For most configs, and with most recent versions of GCC, it's no longer needed. Clarify which cases need it, and only enable it for those cases. Also produce a compile-time error for the ftrace graph + mcount + '-Os' case, which will otherwise cause runtime failures. The main benefit of '-maccumulate-outgoing-args' is that it prevents an ugly prologue for functions which have aligned stacks. But removing the option also has some benefits: more readable argument saves, smaller text size, and (presumably) slightly improved performance. Here are the object size savings for 32-bit and 64-bit defconfig kernels: text data bss dec hex filename 10006710 3543328 1773568 15323606 e9d1d6 vmlinux.x86-32.before 9706358 3547424 1773568 15027350 e54c96 vmlinux.x86-32.after text data bss dec hex filename 10652105 4537576 843776 16033457 f4a6b1 vmlinux.x86-64.before 10639629 4537576 843776 16020981 f475f5 vmlinux.x86-64.after That comes out to a 3% text size improvement on x86-32 and a 0.1% text size improvement on x86-64. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andrew Lutomirski <luto@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20170316193133.zrj6gug53766m6nn@treble Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-09-21lib/raid6: Add AVX512 optimized gen_syndrome functionsGayatri Kammela1-2/+3
Optimize RAID6 gen_syndrom functions to take advantage of the 512-bit ZMM integer instructions introduced in AVX512. AVX512 optimized gen_syndrom functions, which is simply based on avx2.c written by Yuanhan Liu and sse2.c written by hpa. The patch was tested and benchmarked before submission on a hardware that has AVX512 flags to support such instructions Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jim Kukunas <james.t.kukunas@linux.intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Signed-off-by: Megha Dey <megha.dey@linux.intel.com> Signed-off-by: Gayatri Kammela <gayatri.kammela@intel.com> Reviewed-by: Fenghua Yu <fenghua.yu@intel.com> Signed-off-by: Shaohua Li <shli@fb.com>
2016-07-26kbuild: abort build on bad stack protector flagKees Cook1-8/+0
Before, the stack protector flag was sanity checked before .config had been reprocessed. This meant the build couldn't be aborted early, and only a warning could be emitted followed later by the compiler blowing up with an unknown flag. This has caused a lot of confusion over time, so this splits the flag selection from sanity checking and performs the sanity checking after the make has been restarted from a reprocessed .config, so builds can be aborted as early as possible now. Additionally moves the x86-specific sanity check to the same location, since it suffered from the same warn-then-wait-for-compiler-failure problem. Link: http://lkml.kernel.org/r/20160712223043.GA11664@www.outflux.net Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Michal Marek <mmarek@suse.com> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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