From 9cdc3b6a299c6314485bcfb695546c11d35dac4c Mon Sep 17 00:00:00 2001 From: Youling Tang Date: Mon, 1 May 2023 17:19:53 +0800 Subject: LoongArch: ftrace: Add direct call support Select the HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS to provide the register_ftrace_direct[_multi] interfaces allowing users to register the customed trampoline (direct_caller) as the mcount for one or more target functions. And modify_ftrace_direct[_multi] are also provided for modifying direct_caller. There are a few cases to distinguish: - If a direct call ops is the only one tracing a function AND the direct called trampoline is within the reach of a 'bl' instruction -> the ftrace patchsite jumps to the trampoline - Else -> the ftrace patchsite jumps to the ftrace_regs_caller trampoline points to ftrace_list_ops so it iterates over all registered ftrace ops, including the direct call ops and calls its call_direct_funcs handler which stores the direct called trampoline's address in the ftrace_regs and the ftrace_regs_caller trampoline will return to that address instead of returning to the traced function Signed-off-by: Qing Zhang Signed-off-by: Youling Tang Signed-off-by: Huacai Chen --- arch/loongarch/kernel/mcount_dyn.S | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) (limited to 'arch/loongarch/kernel/mcount_dyn.S') diff --git a/arch/loongarch/kernel/mcount_dyn.S b/arch/loongarch/kernel/mcount_dyn.S index bbabf06244c2..c7d961fc72c2 100644 --- a/arch/loongarch/kernel/mcount_dyn.S +++ b/arch/loongarch/kernel/mcount_dyn.S @@ -42,7 +42,6 @@ .if \allregs PTR_S tp, sp, PT_R2 PTR_S t0, sp, PT_R12 - PTR_S t1, sp, PT_R13 PTR_S t2, sp, PT_R14 PTR_S t3, sp, PT_R15 PTR_S t4, sp, PT_R16 @@ -64,6 +63,8 @@ PTR_S zero, sp, PT_R0 .endif PTR_S ra, sp, PT_ERA /* Save trace function ra at PT_ERA */ + move t1, zero + PTR_S t1, sp, PT_R13 PTR_ADDI t8, sp, PT_SIZE PTR_S t8, sp, PT_R3 .endm @@ -104,8 +105,12 @@ ftrace_common_return: 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 jr t0 +.Ldirect: + jr t1 SYM_CODE_END(ftrace_common) SYM_CODE_START(ftrace_caller) @@ -147,3 +152,9 @@ SYM_CODE_START(return_to_handler) jr ra SYM_CODE_END(return_to_handler) #endif + +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS +SYM_CODE_START(ftrace_stub_direct_tramp) + jr t0 +SYM_CODE_END(ftrace_stub_direct_tramp) +#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */ -- cgit v1.2.3