riscv: add CALLER_ADDRx support

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CALLER_ADDRx returns caller's address at specified level, they are used
for several tracers. These macros eventually use
__builtin_return_address(n) to get the caller's address if arch doesn't
define their own implementation.

In RISC-V, __builtin_return_address(n) only works when n == 0, we need
to walk the stack frame to get the caller's address at specified level.

data.level started from 'level + 3' due to the call flow of getting
caller's address in RISC-V implementation. If we don't have additional
three iteration, the level is corresponding to follows:

callsite -> return_address -> arch_stack_walk -> walk_stackframe
|           |                 |                  |
level 3     level 2           level 1            level 0

Fixes: 10626c32e3 ("riscv/ftrace: Add basic support")
Cc: stable@vger.kernel.org
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Signed-off-by: Zong Li <zong.li@sifive.com>
Link: https://lore.kernel.org/r/20240202015102.26251-1-zong.li@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

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Zong Li 2024-02-02 01:51:02 +00:00 • committed by Palmer Dabbelt

parent 4af24146aa

commit 680341382d

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5

arch/riscv/include/asm/ftrace.h

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2

arch/riscv/kernel/Makefile

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48

arch/riscv/kernel/return_address.c

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