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2016-09-23arm64: kgdb: handle read-only text / modulesAKASHI Takahiro1-2/+0
Handle read-only cases when CONFIG_DEBUG_RODATA (4.0) or CONFIG_DEBUG_SET_MODULE_RONX (3.18) are enabled by using aarch64_insn_write() instead of probe_kernel_write() as introduced by commit 2f896d586610 ("arm64: use fixmap for text patching") in 4.0. Fixes: 11d91a770f1f ("arm64: Add CONFIG_DEBUG_SET_MODULE_RONX support") Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-19arm64: Kprobes with single stepping supportSandeepa Prabhu1-0/+5
Add support for basic kernel probes(kprobes) and jump probes (jprobes) for ARM64. Kprobes utilizes software breakpoint and single step debug exceptions supported on ARM v8. A software breakpoint is placed at the probe address to trap the kernel execution into the kprobe handler. ARM v8 supports enabling single stepping before the break exception return (ERET), with next PC in exception return address (ELR_EL1). The kprobe handler prepares an executable memory slot for out-of-line execution with a copy of the original instruction being probed, and enables single stepping. The PC is set to the out-of-line slot address before the ERET. With this scheme, the instruction is executed with the exact same register context except for the PC (and DAIF) registers. Debug mask (PSTATE.D) is enabled only when single stepping a recursive kprobe, e.g.: during kprobes reenter so that probed instruction can be single stepped within the kprobe handler -exception- context. The recursion depth of kprobe is always 2, i.e. upon probe re-entry, any further re-entry is prevented by not calling handlers and the case counted as a missed kprobe). Single stepping from the x-o-l slot has a drawback for PC-relative accesses like branching and symbolic literals access as the offset from the new PC (slot address) may not be ensured to fit in the immediate value of the opcode. Such instructions need simulation, so reject probing them. Instructions generating exceptions or cpu mode change are rejected for probing. Exclusive load/store instructions are rejected too. Additionally, the code is checked to see if it is inside an exclusive load/store sequence (code from Pratyush). System instructions are mostly enabled for stepping, except MSR/MRS accesses to "DAIF" flags in PSTATE, which are not safe for probing. This also changes arch/arm64/include/asm/ptrace.h to use include/asm-generic/ptrace.h. Thanks to Steve Capper and Pratyush Anand for several suggested Changes. Signed-off-by: Sandeepa Prabhu <sandeepa.s.prabhu@gmail.com> Signed-off-by: David A. Long <dave.long@linaro.org> Signed-off-by: Pratyush Anand <panand@redhat.com> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-02-23arm64: move brk immediate argument definitions to separate headerArd Biesheuvel1-13/+1
Instead of reversing the header dependency between asm/bug.h and asm/debug-monitors.h, split off the brk instruction immediate value defines into a new header asm/brk-imm.h, and include it from both. This solves the circular dependency issue that prevents BUG() from being used in some header files, and keeps the definitions together. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-02-18arm64: prevent potential circular header dependencies in asm/bug.hArd Biesheuvel1-1/+1
Currently, using BUG_ON() in header files is cumbersome, due to the fact that asm/bug.h transitively includes a lot of other header files, resulting in the actual BUG_ON() invocation appearing before its definition in the preprocessor input. So let's reverse the #include dependency between asm/bug.h and asm/debug-monitors.h, by moving the definition of BUG_BRK_IMM from the latter to the former. Also fix up one user of asm/debug-monitors.h which relied on a transitive include. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2015-07-27arm64: debug: rename enum debug_el to avoid symbol collisionWill Deacon1-3/+3
lib/list_sort.c defines a 'struct debug_el', where "el" is assumedly a a contraction of "element". This conflicts with 'enum debug_el' in our asm/debug-monitors.h header file, where "el" stands for Exception Level. The result is build failure when targetting allmodconfig, so rename our enum to 'dbg_active_el' to be slightly more explicit about what it is. Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-07-27arm64/BUG: Use BRK instruction for generic BUG trapsDave P Martin1-0/+2
Currently, the minimal default BUG() implementation from asm- generic is used for arm64. This patch uses the BRK software breakpoint instruction to generate a trap instead, similarly to most other arches, with the generic BUG code generating the dmesg boilerplate. This allows bug metadata to be moved to a separate table and reduces the amount of inline code at BUG and WARN sites. This also avoids clobbering any registers before they can be dumped. To mitigate the size of the bug table further, this patch makes use of the existing infrastructure for encoding addresses within the bug table as 32-bit offsets instead of absolute pointers. (Note that this limits the kernel size to 2GB.) Traps are registered at arch_initcall time for aarch64, but BUG has minimal real dependencies and it is desirable to be able to generate bug splats as early as possible. This patch redirects all debug exceptions caused by BRK directly to bug_handler() until the full debug exception support has been initialised. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-07-27arm64/debug: Add missing #includesDave P Martin1-0/+3
<asm/debug-monitors.h> relies on <asm/ptrace.h>, but doesn't declare this dependency. This becomes a problem once debug-monitors.h starts getting included all over the place to get the BRK immedates. The missing include of <asm/memory.h> (for UL()) in <asm/esr.h> is also added. The series no longer relies on this, but I spotted it during development and it may as well get fixed. No functional change. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-07-27arm64/debug: Simplify BRK insn opcode declarationsDave P Martin1-19/+4
The way the KGDB_DYN_BRK_INS_BYTEx macros are declared is more complex than it needs to be. Also, the macros are only used in one place, which is arch-specific anyway. This patch refactors the macros to simplify them, and exposes an argument so that we can have a single macro instead of 4. As a side effect, this patch also fixes some anomalous spellings of "KGDB". These changes alter the compile types of some integer constants that are harmless but trigger truncation warnings in gcc when assigning to 32-bit variables. This patch adds an explicit cast for the affected cases. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-07-27arm64/debug: Move BRK ESR template macro into <asm/esr.h>Dave P Martin1-7/+0
It makes sense to keep all the architectural exception syndrome definitions in the same place. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-07-27arm64/debug: More consistent naming for the BRK ESR template macroDave P Martin1-2/+3
The naming of DBG_ESR_VAL_BRK is inconsistent with the way other similar macros are named. This patch makes the naming more consistent, and appends "64" as a reminder that this ESR pattern only matches from AArch64 state. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-07-27arm64/debug: Eliminate magic number from ESR template definitionDave P Martin1-1/+3
<asm/esr.h> has perfectly good constants for defining ESR values already. Let's use them. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-07-27arm64/debug: Mask off all reserved bits from generated ESR valuesDave P Martin1-1/+1
There are only 16 comment bits in a BRK instruction, which correspond to ESR bits 15:0. Bits 24:16 of the ESR are RES0, and might have weird meanings in the future. This code inserts 16 bits of comment in the ESR value instead of 20 (almost certainly a typo in the original code). Signed-off-by: Dave Martin <Dave.Martin@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-07-27arm64/debug: Eliminate magic number for size of BRK instructionDave P Martin1-1/+3
The size of an A64 BRK instruction is the same as the size of all other A64 instructions, because all A64 instructions are the same size. BREAK_INSTR_SIZE is retained for readibility, but it should not be an independent constant from AARCH64_INSN_SIZE. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2014-09-25arm64: Fix typos in KGDB macrosCatalin Marinas1-11/+11
Some of the KGDB macros used for generating the BRK instructions had the wrong spelling for DBG and KGDB abbreviations. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-09-25arm64: insn: Add return statements after BUG_ON()Mark Brown1-0/+8
Following a recent series of enhancements to the insn code the ARMv8 allnoconfig build has been generating a large number of warnings in the form of: arch/arm64/kernel/insn.c:689:8: warning: 'insn' may be used uninitialized in this function [-Wmaybe-uninitialized] This is because BUG() and related macros can be compiled out so we get execution paths which normally result in a panic compiling out to noops instead. I wasn't able to immediately identify a sensible return value to use in these cases so just return AARCH64_BREAK_FAULT - this is all "should never happen" code so hopefully it never has a practical impact. Signed-off-by: Mark Brown <broonie@kernel.org> [catalin.marinas@arm.com: AARCH64_BREAK_FAULT definition contributed by Daniel Borkmann] [catalin.marinas@arm.com: replace return 0 with AARCH64_BREAK_FAULT] Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-07-11arm64: move DBG_MDSCR_* to asm/debug-monitors.hMarc Zyngier1-5/+14
In order to be able to use the DBG_MDSCR_* macros from the KVM code, move the relevant definitions to the obvious include file. Also move the debug_el enum to a portion of the file that is guarded by #ifndef __ASSEMBLY__ in order to use that file from assembly code. Acked-by: Will Deacon <will.deacon@arm.com> Reviewed-by: Anup Patel <anup.patel@linaro.org> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2014-02-26arm64: KGDB: Add Basic KGDB supportVijaya Kumar K1-0/+47
Add KGDB debug support for kernel debugging. With this patch, basic KGDB debugging is possible.GDB register layout is updated and GDB tool can establish connection with target and can set/clear breakpoints. Signed-off-by: Vijaya Kumar K <Vijaya.Kumar@caviumnetworks.com> Reviewed-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-02-26arm64: Add macros to manage processor debug stateVijaya Kumar K1-17/+0
Add macros to enable and disable to manage PSTATE.D for debugging. The macros local_dbg_save and local_dbg_restore are moved to irqflags.h file KGDB boot tests fail because of PSTATE.D is masked. unmask it for debugging support Signed-off-by: Vijaya Kumar K <Vijaya.Kumar@caviumnetworks.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2013-12-19arm64: support single-step and breakpoint handler hooksSandeepa Prabhu1-0/+21
AArch64 Single Steping and Breakpoint debug exceptions will be used by multiple debug framworks like kprobes & kgdb. This patch implements the hooks for those frameworks to register their own handlers for handling breakpoint and single step events. Reworked the debug exception handler in entry.S: do_dbg to route software breakpoint (BRK64) exception to do_debug_exception() Signed-off-by: Sandeepa Prabhu <sandeepa.prabhu@linaro.org> Signed-off-by: Deepak Saxena <dsaxena@linaro.org> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2013-07-19arm64: add '#ifdef CONFIG_COMPAT' for aarch32_break_handler()Chen Gang1-7/+0
If 'COMPAT' not defined, aarch32_break_handler() cannot pass compiling, and it can work independent with 'COMPAT', so remove dummy definition. The related error: arch/arm64/kernel/debug-monitors.c:249:5: error: redefinition of ‘aarch32_break_handler’ In file included from arch/arm64/kernel/debug-monitors.c:29:0: /root/linux-next/arch/arm64/include/asm/debug-monitors.h:89:12: note: previous definition of ‘aarch32_break_handler’ was here Signed-off-by: Chen Gang <gang.chen@asianux.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2013-06-12arm64: debug: consolidate software breakpoint handlersWill Deacon1-0/+9
The software breakpoint handlers are hooked in directly from ptrace, which makes it difficult to add additional handlers for things like kprobes and kgdb. This patch moves the handling code into debug-monitors.c, where we can dispatch to different debug subsystems more easily. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2012-09-17arm64: Debugging supportWill Deacon1-0/+88
This patch adds ptrace, debug monitors and hardware breakpoints support. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>