Chen Zhongjin 98bada8fa0 x86/unwind/orc: Fix unreliable stack dump with gcov ... [ Upstream commit 230db82413 ] When a console stack dump is initiated with CONFIG_GCOV_PROFILE_ALL enabled, show_trace_log_lvl() gets out of sync with the ORC unwinder, causing the stack trace to show all text addresses as unreliable: # echo l > /proc/sysrq-trigger [ 477.521031] sysrq: Show backtrace of all active CPUs [ 477.523813] NMI backtrace for cpu 0 [ 477.524492] CPU: 0 PID: 1021 Comm: bash Not tainted 6.0.0 #65 [ 477.525295] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.0-1.fc36 04/01/2014 [ 477.526439] Call Trace: [ 477.526854] <TASK> [ 477.527216] ? dump_stack_lvl+0xc7/0x114 [ 477.527801] ? dump_stack+0x13/0x1f [ 477.528331] ? nmi_cpu_backtrace.cold+0xb5/0x10d [ 477.528998] ? lapic_can_unplug_cpu+0xa0/0xa0 [ 477.529641] ? nmi_trigger_cpumask_backtrace+0x16a/0x1f0 [ 477.530393] ? arch_trigger_cpumask_backtrace+0x1d/0x30 [ 477.531136] ? sysrq_handle_showallcpus+0x1b/0x30 [ 477.531818] ? __handle_sysrq.cold+0x4e/0x1ae [ 477.532451] ? write_sysrq_trigger+0x63/0x80 [ 477.533080] ? proc_reg_write+0x92/0x110 [ 477.533663] ? vfs_write+0x174/0x530 [ 477.534265] ? handle_mm_fault+0x16f/0x500 [ 477.534940] ? ksys_write+0x7b/0x170 [ 477.535543] ? __x64_sys_write+0x1d/0x30 [ 477.536191] ? do_syscall_64+0x6b/0x100 [ 477.536809] ? entry_SYSCALL_64_after_hwframe+0x63/0xcd [ 477.537609] </TASK> This happens when the compiled code for show_stack() has a single word on the stack, and doesn't use a tail call to show_stack_log_lvl(). (CONFIG_GCOV_PROFILE_ALL=y is the only known case of this.) Then the __unwind_start() skip logic hits an off-by-one bug and fails to unwind all the way to the intended starting frame. Fix it by reverting the following commit: f1d9a2abff ("x86/unwind/orc: Don't skip the first frame for inactive tasks") The original justification for that commit no longer exists. That original issue was later fixed in a different way, with the following commit: f2ac57a4c4 ("x86/unwind/orc: Fix inactive tasks with stack pointer in %sp on GCC 10 compiled kernels") Fixes: f1d9a2abff ("x86/unwind/orc: Don't skip the first frame for inactive tasks") Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com> [jpoimboe: rewrite commit log] Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Sasha Levin <sashal@kernel.org>		2022-11-03 23:59:16 +09:00
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alpha	…
arc	arc: iounmap() arg is volatile	2022-11-03 23:59:15 +09:00
arm	ARM: 9242/1: kasan: Only map modules if CONFIG_KASAN_VMALLOC=n	2022-10-26 12:35:45 +02:00
arm64	arm64: mte: move register initialization to C	2022-10-29 10:12:57 +02:00
csky	…
h8300	…
hexagon	…
ia64	ia64: export memory_add_physaddr_to_nid to fix cxl build error	2022-10-26 12:34:59 +02:00
m68k	…
microblaze	…
mips	MIPS: BCM47XX: Cast memcmp() of function to (void *)	2022-10-26 12:35:30 +02:00
nds32	…
nios2	…
openrisc	…
parisc	…
powerpc	powerpc/pseries/vas: Pass hw_cpu_id to node associativity HCALL	2022-10-26 12:35:23 +02:00
riscv	…
s390	s390/pci: add missing EX_TABLE entries to __pcistg_mio_inuser()/__pcilg_mio_inuser()	2022-11-03 23:59:13 +09:00
sh	sh: machvec: Use char[] for section boundaries	2022-10-26 12:34:36 +02:00
sparc	…
um	…
x86	x86/unwind/orc: Fix unreliable stack dump with gcov	2022-11-03 23:59:16 +09:00
xtensa	…
.gitignore	…
Kconfig	…