From ade8c20847fcc3f4de08b35f730ec04ef29ddbdc Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Thu, 15 Dec 2022 17:43:23 +0100 Subject: x86/calldepth: Fix incorrect init section references The addition of callthunks_translate_call_dest means that skip_addr() and patch_dest() can no longer be discarded as part of the __init section freeing: WARNING: modpost: vmlinux.o: section mismatch in reference: callthunks_translate_call_dest.cold (section: .text.unlikely) -> skip_addr (section: .init.text) WARNING: modpost: vmlinux.o: section mismatch in reference: callthunks_translate_call_dest.cold (section: .text.unlikely) -> patch_dest (section: .init.text) WARNING: modpost: vmlinux.o: section mismatch in reference: is_callthunk.cold (section: .text.unlikely) -> skip_addr (section: .init.text) ERROR: modpost: Section mismatches detected. Set CONFIG_SECTION_MISMATCH_WARN_ONLY=y to allow them. Fixes: b2e9dfe54be4 ("x86/bpf: Emit call depth accounting if required") Signed-off-by: Arnd Bergmann Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20221215164334.968863-1-arnd@kernel.org --- arch/x86/kernel/callthunks.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch') diff --git a/arch/x86/kernel/callthunks.c b/arch/x86/kernel/callthunks.c index 7d2c75ec9a8c..ffea98f9064b 100644 --- a/arch/x86/kernel/callthunks.c +++ b/arch/x86/kernel/callthunks.c @@ -119,7 +119,7 @@ static bool is_coretext(const struct core_text *ct, void *addr) return within_module_coretext(addr); } -static __init_or_module bool skip_addr(void *dest) +static bool skip_addr(void *dest) { if (dest == error_entry) return true; @@ -181,7 +181,7 @@ static const u8 nops[] = { 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, }; -static __init_or_module void *patch_dest(void *dest, bool direct) +static void *patch_dest(void *dest, bool direct) { unsigned int tsize = SKL_TMPL_SIZE; u8 *pad = dest - tsize; -- cgit v1.2.3 From 1993bf97992df2d560287f3c4120eda57426843d Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Mon, 19 Dec 2022 23:35:10 +0900 Subject: x86/kprobes: Fix kprobes instruction boudary check with CONFIG_RETHUNK Since the CONFIG_RETHUNK and CONFIG_SLS will use INT3 for stopping speculative execution after RET instruction, kprobes always failes to check the probed instruction boundary by decoding the function body if the probed address is after such sequence. (Note that some conditional code blocks will be placed after function return, if compiler decides it is not on the hot path.) This is because kprobes expects kgdb puts the INT3 as a software breakpoint and it will replace the original instruction. But these INT3 are not such purpose, it doesn't need to recover the original instruction. To avoid this issue, kprobes checks whether the INT3 is owned by kgdb or not, and if so, stop decoding and make it fail. The other INT3 will come from CONFIG_RETHUNK/CONFIG_SLS and those can be treated as a one-byte instruction. Fixes: e463a09af2f0 ("x86: Add straight-line-speculation mitigation") Suggested-by: Peter Zijlstra Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Peter Zijlstra (Intel) Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/167146051026.1374301.392728975473572291.stgit@devnote3 --- arch/x86/kernel/kprobes/core.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'arch') diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 66299682b6b7..b36f3c367cb2 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -37,6 +37,7 @@ #include #include #include +#include #include #include #include @@ -281,12 +282,15 @@ static int can_probe(unsigned long paddr) if (ret < 0) return 0; +#ifdef CONFIG_KGDB /* - * Another debugging subsystem might insert this breakpoint. - * In that case, we can't recover it. + * If there is a dynamically installed kgdb sw breakpoint, + * this function should not be probed. */ - if (insn.opcode.bytes[0] == INT3_INSN_OPCODE) + if (insn.opcode.bytes[0] == INT3_INSN_OPCODE && + kgdb_has_hit_break(addr)) return 0; +#endif addr += insn.length; } -- cgit v1.2.3 From 63dc6325ff41ee9e570bde705ac34a39c5dbeb44 Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Mon, 19 Dec 2022 23:35:19 +0900 Subject: x86/kprobes: Fix optprobe optimization check with CONFIG_RETHUNK Since the CONFIG_RETHUNK and CONFIG_SLS will use INT3 for stopping speculative execution after function return, kprobe jump optimization always fails on the functions with such INT3 inside the function body. (It already checks the INT3 padding between functions, but not inside the function) To avoid this issue, as same as kprobes, check whether the INT3 comes from kgdb or not, and if so, stop decoding and make it fail. The other INT3 will come from CONFIG_RETHUNK/CONFIG_SLS and those can be treated as a one-byte instruction. Fixes: e463a09af2f0 ("x86: Add straight-line-speculation mitigation") Suggested-by: Peter Zijlstra Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Peter Zijlstra (Intel) Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/167146051929.1374301.7419382929328081706.stgit@devnote3 --- arch/x86/kernel/kprobes/opt.c | 28 ++++++++-------------------- 1 file changed, 8 insertions(+), 20 deletions(-) (limited to 'arch') diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c index e6b8c5362b94..e57e07b0edb6 100644 --- a/arch/x86/kernel/kprobes/opt.c +++ b/arch/x86/kernel/kprobes/opt.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -279,19 +280,6 @@ static int insn_is_indirect_jump(struct insn *insn) return ret; } -static bool is_padding_int3(unsigned long addr, unsigned long eaddr) -{ - unsigned char ops; - - for (; addr < eaddr; addr++) { - if (get_kernel_nofault(ops, (void *)addr) < 0 || - ops != INT3_INSN_OPCODE) - return false; - } - - return true; -} - /* Decode whole function to ensure any instructions don't jump into target */ static int can_optimize(unsigned long paddr) { @@ -334,15 +322,15 @@ static int can_optimize(unsigned long paddr) ret = insn_decode_kernel(&insn, (void *)recovered_insn); if (ret < 0) return 0; - +#ifdef CONFIG_KGDB /* - * In the case of detecting unknown breakpoint, this could be - * a padding INT3 between functions. Let's check that all the - * rest of the bytes are also INT3. + * If there is a dynamically installed kgdb sw breakpoint, + * this function should not be probed. */ - if (insn.opcode.bytes[0] == INT3_INSN_OPCODE) - return is_padding_int3(addr, paddr - offset + size) ? 1 : 0; - + if (insn.opcode.bytes[0] == INT3_INSN_OPCODE && + kgdb_has_hit_break(addr)) + return 0; +#endif /* Recover address */ insn.kaddr = (void *)addr; insn.next_byte = (void *)(addr + insn.length); -- cgit v1.2.3