Messages in this thread Patch in this message | | | From | Li Huafei <> | Subject | [PATCH -next] arm64: ftrace: Add DYNAMIC_FTRACE_WITH_ARGS support | Date | Wed, 20 Apr 2022 10:09:42 +0800 |
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DYNAMIC_FTRACE_WITH_ARGS allows ftrace_ops without the FL_SAVE_REGS flag set (via the "ftrace_caller" trampoline) to fetch all parameters and stack pointer. On arm64, under the DYNAMIC_FTRACE_WITH_REGS implementation, ftrace_caller() already supports filling the above registers into pt_regs, all that remains to be done is to ensure that arch_ftrace_get_regs() returns NULL when FL_SAVE_REGS is not set. We use pt_regs::regs[10] to identify whether the FL_SAVE_REGS flag is set.
The mcount-based implementation supports DYNAMIC_FTRACE_WITH_ARGS with some difficulty, as some registers (e.g. X0) are already clobbered before entering the trampoline. We need to rely on gcc's "-fpatchable-function-entry" feature, so here we have DYNAMIC_FTRACE_WITH_ARGS depending on DYNAMIC_FTRACE_WITH_REGS, and the mcount-based implementation is unaffected.
Signed-off-by: Li Huafei <lihuafei1@huawei.com> --- arch/arm64/Kconfig | 2 ++ arch/arm64/include/asm/ftrace.h | 17 +++++++++++++++++ arch/arm64/kernel/entry-ftrace.S | 5 +++++ 3 files changed, 24 insertions(+)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 18a18a0e855d..a1b4c5800b38 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -177,6 +177,8 @@ config ARM64 select HAVE_DEBUG_KMEMLEAK select HAVE_DMA_CONTIGUOUS select HAVE_DYNAMIC_FTRACE + select HAVE_DYNAMIC_FTRACE_WITH_ARGS \ + if HAVE_DYNAMIC_FTRACE_WITH_REGS select FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY \ if DYNAMIC_FTRACE_WITH_REGS select HAVE_EFFICIENT_UNALIGNED_ACCESS diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h index 1494cfa8639b..2b4cd442c843 100644 --- a/arch/arm64/include/asm/ftrace.h +++ b/arch/arm64/include/asm/ftrace.h @@ -78,6 +78,23 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr) return addr; } +#ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS +struct ftrace_regs { + struct pt_regs regs; +}; + +static __always_inline struct pt_regs * +arch_ftrace_get_regs(struct ftrace_regs *fregs) +{ + struct pt_regs *regs = &fregs->regs; + + /* When FL_SAVE_REGS is not set, X10 is set to zero */ + if (!pt_regs_read_reg(regs, 10)) + return NULL; + return regs; +} +#endif /* CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */ + #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS struct dyn_ftrace; int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec); diff --git a/arch/arm64/kernel/entry-ftrace.S b/arch/arm64/kernel/entry-ftrace.S index e535480a4069..805287fedb01 100644 --- a/arch/arm64/kernel/entry-ftrace.S +++ b/arch/arm64/kernel/entry-ftrace.S @@ -46,6 +46,8 @@ /* Optionally save the callee-saved registers, always save the FP */ .if \allregs == 1 + /* Set X10 to 1 (just non-zero) for ops with FL_SAVE_REGS flag set */ + mov x10, #1 stp x10, x11, [sp, #S_X10] stp x12, x13, [sp, #S_X12] stp x14, x15, [sp, #S_X14] @@ -57,6 +59,9 @@ stp x26, x27, [sp, #S_X26] stp x28, x29, [sp, #S_X28] .else + /* Set X10 to 0 for ops without FL_SAVE_REGS flag */ + mov x10, #0 + str x10, [sp, #S_X10] str x29, [sp, #S_FP] .endif -- 2.17.1
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