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authorTobias Klauser <tklauser@xenon.tklauser.home>2006-07-01 16:56:14 +0200
committerTobias Klauser <tklauser@xenon.tklauser.home>2006-07-01 16:56:14 +0200
commitb19e7a6a88355d32501b48a0b3f6b7f56c463b2a (patch)
treedcb927a6ef4dc85312f2fc88de22255c8df5db7a /Makefile
parentd8cb881f04be06d0427a4956ff85311922cc5820 (diff)
Cleanup
Diffstat (limited to 'Makefile')
0 files changed, 0 insertions, 0 deletions
a'>096b3224d5e7239ec3e5033bbc7612ac2d5dec3a (diff)
arm64: Synchronise dump_backtrace() with perf callchain
Unlike perf callchain relying on walk_stackframe(), dump_backtrace() has its own backtrace logic. A major difference between them is the moment a symbol is recorded. Perf writes down a symbol *before* calling unwind_frame(), but dump_backtrace() prints it out *after* unwind_frame(). As a result, the last valid symbol cannot be hooked in case of dump_backtrace(). This patch addresses the issue as synchronising dump_backtrace() with perf callchain. A simple test and its results are as follows: - crash trigger $ sudo echo c > /proc/sysrq-trigger - current status Call trace: [<fffffe00003dc738>] sysrq_handle_crash+0x24/0x30 [<fffffe00003dd2ac>] __handle_sysrq+0x128/0x19c [<fffffe00003dd730>] write_sysrq_trigger+0x60/0x74 [<fffffe0000249fc4>] proc_reg_write+0x84/0xc0 [<fffffe00001f2638>] __vfs_write+0x44/0x104 [<fffffe00001f2e60>] vfs_write+0x98/0x1a8 [<fffffe00001f3730>] SyS_write+0x50/0xb0 - with this change Call trace: [<fffffe00003dc738>] sysrq_handle_crash+0x24/0x30 [<fffffe00003dd2ac>] __handle_sysrq+0x128/0x19c [<fffffe00003dd730>] write_sysrq_trigger+0x60/0x74 [<fffffe0000249fc4>] proc_reg_write+0x84/0xc0 [<fffffe00001f2638>] __vfs_write+0x44/0x104 [<fffffe00001f2e60>] vfs_write+0x98/0x1a8 [<fffffe00001f3730>] SyS_write+0x50/0xb0 [<fffffe00000939ec>] el0_svc_naked+0x20/0x28 Note that this patch does not cover a case where MMU is disabled. The last stack frame of swapper, for example, has PC in a form of physical address. Unfortunately, a simple conversion using phys_to_virt() cannot cover all scenarios since PC is retrieved from LR - 4, not LR. It is a big tradeoff to change both head.S and unwind_frame() for only a few of symbols in *.S. Thus, this hunk does not take care of the case. Cc: AKASHI Takahiro <takahiro.akashi@linaro.org> Cc: James Morse <james.morse@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Jungseok Lee <jungseoklee85@gmail.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel/traps.c')