diff options
| author | Chenghao Duan <duanchenghao@kylinos.cn> | 2025-12-31 15:19:20 +0800 |
|---|---|---|
| committer | Huacai Chen <chenhuacai@loongson.cn> | 2025-12-31 15:19:20 +0800 |
| commit | 45cb47c628dfbd1994c619f3eac271a780602826 (patch) | |
| tree | c7adca4f090386b9e4c521d428bb4c4dbbb80e40 /arch | |
| parent | 9bdc1ab5e4ce6f066119018d8f69631a46f9c5a0 (diff) | |
LoongArch: Refactor register restoration in ftrace_common_return
Refactor the register restoration sequence in the ftrace_common_return
function to clearly distinguish between the logic of normal returns and
direct call returns in function tracing scenarios. The logic is as
follows:
1. In the case of a normal return, the execution flow returns to the
traced function, and ftrace must ensure that the register data is
consistent with the state when the function was entered.
ra = parent return address; t0 = traced function return address.
2. In the case of a direct call return, the execution flow jumps to the
custom trampoline function, and ftrace must ensure that the register
data is consistent with the state when ftrace was entered.
ra = traced function return address; t0 = parent return address.
Cc: stable@vger.kernel.org
Fixes: 9cdc3b6a299c ("LoongArch: ftrace: Add direct call support")
Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/loongarch/kernel/mcount_dyn.S | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/arch/loongarch/kernel/mcount_dyn.S b/arch/loongarch/kernel/mcount_dyn.S index d6b474ad1d5e..5729c20e5b8b 100644 --- a/arch/loongarch/kernel/mcount_dyn.S +++ b/arch/loongarch/kernel/mcount_dyn.S @@ -94,7 +94,6 @@ SYM_INNER_LABEL(ftrace_graph_call, SYM_L_GLOBAL) * at the callsite, so there is no need to restore the T series regs. */ ftrace_common_return: - PTR_L ra, sp, PT_R1 PTR_L a0, sp, PT_R4 PTR_L a1, sp, PT_R5 PTR_L a2, sp, PT_R6 @@ -104,12 +103,17 @@ ftrace_common_return: PTR_L a6, sp, PT_R10 PTR_L a7, sp, PT_R11 PTR_L fp, sp, PT_R22 - PTR_L t0, sp, PT_ERA PTR_L t1, sp, PT_R13 - PTR_ADDI sp, sp, PT_SIZE bnez t1, .Ldirect + + PTR_L ra, sp, PT_R1 + PTR_L t0, sp, PT_ERA + PTR_ADDI sp, sp, PT_SIZE jr t0 .Ldirect: + PTR_L t0, sp, PT_R1 + PTR_L ra, sp, PT_ERA + PTR_ADDI sp, sp, PT_SIZE jr t1 SYM_CODE_END(ftrace_common) @@ -161,6 +165,8 @@ SYM_CODE_END(return_to_handler) #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS SYM_CODE_START(ftrace_stub_direct_tramp) UNWIND_HINT_UNDEFINED - jr t0 + move t1, ra + move ra, t0 + jr t1 SYM_CODE_END(ftrace_stub_direct_tramp) #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */ |