diff options
| author | Ard Biesheuvel <ardb@kernel.org> | 2022-01-25 15:55:24 +0100 |
|---|---|---|
| committer | Ard Biesheuvel <ardb@kernel.org> | 2022-02-09 09:13:59 +0100 |
| commit | 41918ec82eb6f80c8b401422f27ca76c85aa0cb7 (patch) | |
| tree | 1bd1010a1e6e5a52d3c4ed22d768f863ce10dc6a /arch/arm/kernel/ftrace.c | |
| parent | ARM: unwind: track location of LR value in stack frame (diff) | |
| download | linux-41918ec82eb6f80c8b401422f27ca76c85aa0cb7.tar.xz linux-41918ec82eb6f80c8b401422f27ca76c85aa0cb7.zip | |
ARM: ftrace: enable the graph tracer with the EABI unwinder
Enable the function graph tracer in combination with the EABI unwinder,
so that Thumb2 builds or Clang ARM builds can make use of it.
This involves using the unwinder to locate the return address of an
instrumented function on the stack, so that it can be overridden and
made to refer to the ftrace handling routines that need to be called at
function return.
Given that for these builds, it is not guaranteed that the value of the
link register is stored on the stack, fall back to the stack slot that
will be used by the ftrace exit code to restore LR in the instrumented
function's execution context.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'arch/arm/kernel/ftrace.c')
| -rw-r--r-- | arch/arm/kernel/ftrace.c | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c index ea2396900c7d..83cc068586bc 100644 --- a/arch/arm/kernel/ftrace.c +++ b/arch/arm/kernel/ftrace.c @@ -22,6 +22,7 @@ #include <asm/ftrace.h> #include <asm/insn.h> #include <asm/set_memory.h> +#include <asm/stacktrace.h> #include <asm/patch.h> /* @@ -224,8 +225,10 @@ int ftrace_make_nop(struct module *mod, #endif /* CONFIG_DYNAMIC_FTRACE */ #ifdef CONFIG_FUNCTION_GRAPH_TRACER +asmlinkage void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, - unsigned long frame_pointer) + unsigned long frame_pointer, + unsigned long stack_pointer) { unsigned long return_hooker = (unsigned long) &return_to_handler; unsigned long old; @@ -236,6 +239,18 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, if (IS_ENABLED(CONFIG_UNWINDER_FRAME_POINTER)) { /* FP points one word below parent's top of stack */ frame_pointer += 4; + } else { + struct stackframe frame = { + .fp = frame_pointer, + .sp = stack_pointer, + .lr = self_addr, + .pc = self_addr, + }; + if (unwind_frame(&frame) < 0) + return; + if (frame.lr != self_addr) + parent = frame.lr_addr; + frame_pointer = frame.sp; } old = *parent; @@ -258,7 +273,7 @@ static int __ftrace_modify_caller(unsigned long *callsite, unsigned long caller_fn = (unsigned long) func; unsigned long pc = (unsigned long) callsite; unsigned long branch = arm_gen_branch(pc, caller_fn); - unsigned long nop = 0xe1a00000; /* mov r0, r0 */ + unsigned long nop = arm_gen_nop(); unsigned long old = enable ? nop : branch; unsigned long new = enable ? branch : nop; |