x86/unwind/orc: Unwind ftrace trampolines with correct ORC entry
authorChen Zhongjin <chenzhongjin@huawei.com>
Fri, 19 Aug 2022 08:43:34 +0000 (16:43 +0800)
committerIngo Molnar <mingo@kernel.org>
Sun, 21 Aug 2022 10:19:32 +0000 (12:19 +0200)
commitfc2e426b1161761561624ebd43ce8c8d2fa058da
treecf3fc2b6fb75af4db55ae3a7776aab2e5d45158d
parent332924973725e8cdcc783c175f68cf7e162cb9e5
x86/unwind/orc: Unwind ftrace trampolines with correct ORC entry

When meeting ftrace trampolines in ORC unwinding, unwinder uses address
of ftrace_{regs_}call address to find the ORC entry, which gets next frame at
sp+176.

If there is an IRQ hitting at sub $0xa8,%rsp, the next frame should be
sp+8 instead of 176. It makes unwinder skip correct frame and throw
warnings such as "wrong direction" or "can't access registers", etc,
depending on the content of the incorrect frame address.

By adding the base address ftrace_{regs_}caller with the offset
*ip - ops->trampoline*, we can get the correct address to find the ORC entry.

Also change "caller" to "tramp_addr" to make variable name conform to
its content.

[ mingo: Clarified the changelog a bit. ]

Fixes: 6be7fa3c74d1 ("ftrace, orc, x86: Handle ftrace dynamically allocated trampolines")
Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220819084334.244016-1-chenzhongjin@huawei.com
arch/x86/kernel/unwind_orc.c