[PATCH V9 3/4] riscv: ftrace: Add DYNAMIC_FTRACE_WITH_DIRECT_CALLS support
From: Song Shuai <hidden>
Date: 2023-05-10 10:19:40
Also in:
linux-riscv, lkml
Subsystem:
function hooks (ftrace), risc-v architecture, the rest · Maintainers:
Steven Rostedt, Masami Hiramatsu, Paul Walmsley, Palmer Dabbelt, Albert Ou, Linus Torvalds
This patch adds DYNAMIC_FTRACE_WITH_DIRECT_CALLS support for RISC-V. select the 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. To make the direct_caller and the other ftrace hooks (eg. function/fgraph tracer, k[ret]probes) co-exist, a temporary register is nominated to store the address of direct_caller in ftrace_regs_caller. After the setting of the address direct_caller by direct_ops->func and the RESTORE_REGS in ftrace_regs_caller, direct_caller will be jumped to by the `jr` inst. Signed-off-by: Song Shuai <redacted> Tested-by: Guo Ren <guoren@kernel.org> Signed-off-by: Guo Ren <guoren@kernel.org> --- arch/riscv/Kconfig | 1 + arch/riscv/include/asm/ftrace.h | 8 ++++++++ arch/riscv/kernel/mcount-dyn.S | 10 ++++++++++ 3 files changed, 19 insertions(+)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index e0632493482f..fdf0b219a02c 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig@@ -144,6 +144,7 @@ config RISCV select UACCESS_MEMCPY if !MMU select ZONE_DMA32 if 64BIT select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && MMU && (CLANG_SUPPORTS_DYNAMIC_FTRACE || GCC_SUPPORTS_DYNAMIC_FTRACE) + select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL select HAVE_FUNCTION_GRAPH_TRACER
diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
index 84f856a3286e..84904c1e4369 100644
--- a/arch/riscv/include/asm/ftrace.h
+++ b/arch/riscv/include/asm/ftrace.h@@ -114,6 +114,14 @@ struct ftrace_regs; void ftrace_graph_func(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *op, struct ftrace_regs *fregs); #define ftrace_graph_func ftrace_graph_func + +static inline void +__arch_ftrace_set_direct_caller(struct pt_regs *regs, unsigned long addr) +{ + regs->t1 = addr; +} +#define arch_ftrace_set_direct_caller(fregs, addr) \ + __arch_ftrace_set_direct_caller(&(fregs)->regs, addr) #endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */ #endif /* __ASSEMBLY__ */
diff --git a/arch/riscv/kernel/mcount-dyn.S b/arch/riscv/kernel/mcount-dyn.S
index f26e9f6e2fed..9d405baedb52 100644
--- a/arch/riscv/kernel/mcount-dyn.S
+++ b/arch/riscv/kernel/mcount-dyn.S@@ -231,6 +231,7 @@ ENDPROC(ftrace_caller) #else /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */ ENTRY(ftrace_regs_caller) + move t1, zero SAVE_ABI_REGS 1 PREPARE_ARGS
@@ -239,7 +240,10 @@ ftrace_regs_call: call ftrace_stub RESTORE_ABI_REGS 1 + bnez t1,.Ldirect jr t0 +.Ldirect: + jr t1 ENDPROC(ftrace_regs_caller) ENTRY(ftrace_caller)
@@ -254,3 +258,9 @@ ftrace_call: jr t0 ENDPROC(ftrace_caller) #endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */ + +#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 */
--
2.20.1