linux

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Masami Hiramatsu 7e9bf33b81 ARM: kprobes: Make a frame pointer on __kretprobe_trampoline

Currently kretprobe on ARM just fills r0-r11 of pt_regs, but
that is not enough for the stacktrace. Moreover, from the user
kretprobe handler, stacktrace needs a frame pointer on the
__kretprobe_trampoline.

This adds a frame pointer on __kretprobe_trampoline for both gcc
and clang case. Those have different frame pointer so we need
different but similar stack on pt_regs.

Gcc makes the frame pointer (fp) to point the 'pc' address of
the {fp, ip (=sp), lr, pc}, this means {r11, r13, r14, r15}.
Thus if we save the r11 (fp) on pt_regs->r12, we can make this
set on the end of pt_regs.

On the other hand, Clang makes the frame pointer to point the
'fp' address of {fp, lr} on stack. Since the next to the
pt_regs->lr is pt_regs->sp, I reused the pair of pt_regs->fp
and pt_regs->ip.
So this stores the 'lr' on pt_regs->ip and make the fp to point
pt_regs->fp.

For both cases, saves __kretprobe_trampoline address to
pt_regs->lr, so that the stack tracer can identify this frame
pointer has been made by the __kretprobe_trampoline.

Note that if the CONFIG_FRAME_POINTER is not set, this keeps
fp as is.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

2021-10-22 12:16:53 -04:00

kprobes

ARM: kprobes: Make a frame pointer on __kretprobe_trampoline

2021-10-22 12:16:53 -04:00

uprobes

ARM: 9071/1: uprobes: Don't hook on thumb instructions

2021-04-18 19:14:45 +01:00

decode-arm.c

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174

2019-05-30 11:26:41 -07:00

decode-arm.h

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 159