| Message ID | 172639147435.366111.834128908630424679.stgit@devnote2 (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Guessing tree name failed - patch did not apply |
On Sun, Sep 15, 2024 at 06:11:14PM +0900, Masami Hiramatsu (Google) wrote: > From: Masami Hiramatsu (Google) <mhiramat@kernel.org> > > Add ftrace_fill_perf_regs() which should be compatible with the > perf_fetch_caller_regs(). In other words, the pt_regs returned from the > ftrace_fill_perf_regs() must satisfy 'user_mode(regs) == false' and can be > used for stack tracing. > > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> ... > arch/s390/include/asm/ftrace.h | 5 +++++ ... > diff --git a/arch/s390/include/asm/ftrace.h b/arch/s390/include/asm/ftrace.h > index 9cdd48a46bf7..0d9f6df21f81 100644 > --- a/arch/s390/include/asm/ftrace.h > +++ b/arch/s390/include/asm/ftrace.h > @@ -84,6 +84,11 @@ ftrace_regs_get_frame_pointer(struct ftrace_regs *fregs) > return sp[0]; /* return backchain */ > } > > +#define arch_ftrace_fill_perf_regs(fregs, _regs) do { \ > + (_regs)->psw.addr = (fregs)->regs.psw.addr; \ > + (_regs)->gprs[15] = (fregs)->regs.gprs[15]; \ > + } while (0) After reading your commit description and looking at the code I think the s390 implementation of perf_arch_fetch_caller_regs() is at least suboptimal: it is not possible to tell if an address belongs to user or kernel space by looking only at the address (psw.addr); this also requires to look at psw.mask. It _looks_ like all current callers of perf_arch_fetch_caller_regs() initialize the passed in pt_regs to zero, which of course also sets psw.mask to zero, and therefore user_mode(regs) == false is satisfied. However I'd rather make that explicit and don't want to rely on callers. Therefore the above arch_ftrace_fill_perf_regs() should set the mask to zero (_regs)->psw.mask = 0; I will change perf_arch_fetch_caller_regs() accordingly.
diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h index 5cd587afab6d..14ecb9a418d9 100644 --- a/arch/arm64/include/asm/ftrace.h +++ b/arch/arm64/include/asm/ftrace.h @@ -143,6 +143,13 @@ ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs) return regs; } +#define arch_ftrace_fill_perf_regs(fregs, _regs) do { \ + (_regs)->pc = (fregs)->pc; \ + (_regs)->regs[29] = (fregs)->fp; \ + (_regs)->sp = (fregs)->sp; \ + (_regs)->pstate = PSR_MODE_EL1h; \ + } while (0) + int ftrace_regs_query_register_offset(const char *name); int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec); diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h index 23d26f3afae4..e6ff6834bf7e 100644 --- a/arch/powerpc/include/asm/ftrace.h +++ b/arch/powerpc/include/asm/ftrace.h @@ -42,6 +42,13 @@ static __always_inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs * return fregs->regs.msr ? &fregs->regs : NULL; } +#define arch_ftrace_fill_perf_regs(fregs, _regs) do { \ + (_regs)->result = 0; \ + (_regs)->nip = (fregs)->regs.nip; \ + (_regs)->gpr[1] = (fregs)->regs.gpr[1]; \ + asm volatile("mfmsr %0" : "=r" ((_regs)->msr)); \ + } while (0) + static __always_inline void ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs, unsigned long ip) diff --git a/arch/s390/include/asm/ftrace.h b/arch/s390/include/asm/ftrace.h index 9cdd48a46bf7..0d9f6df21f81 100644 --- a/arch/s390/include/asm/ftrace.h +++ b/arch/s390/include/asm/ftrace.h @@ -84,6 +84,11 @@ ftrace_regs_get_frame_pointer(struct ftrace_regs *fregs) return sp[0]; /* return backchain */ } +#define arch_ftrace_fill_perf_regs(fregs, _regs) do { \ + (_regs)->psw.addr = (fregs)->regs.psw.addr; \ + (_regs)->gprs[15] = (fregs)->regs.gprs[15]; \ + } while (0) + #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS /* * When an ftrace registered caller is tracing a function that is diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h index 669771ef3b5b..1f4d1f7b19ed 100644 --- a/arch/x86/include/asm/ftrace.h +++ b/arch/x86/include/asm/ftrace.h @@ -46,6 +46,13 @@ arch_ftrace_get_regs(struct ftrace_regs *fregs) return &fregs->regs; } +#define arch_ftrace_fill_perf_regs(fregs, _regs) do { \ + (_regs)->ip = (fregs)->regs.ip; \ + (_regs)->sp = (fregs)->regs.sp; \ + (_regs)->cs = __KERNEL_CS; \ + (_regs)->flags = 0; \ + } while (0) + #define ftrace_regs_set_instruction_pointer(fregs, _ip) \ do { (fregs)->regs.ip = (_ip); } while (0) diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index d6b92a4091b9..cc6bf05a9992 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -193,6 +193,37 @@ ftrace_partial_regs(struct ftrace_regs *fregs, struct pt_regs *regs) #endif /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS || CONFIG_HAVE_PT_REGS_TO_FTRACE_REGS_CAST */ +#ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS + +/* + * Please define arch dependent pt_regs which compatible to the + * perf_arch_fetch_caller_regs() but based on ftrace_regs. + * This requires + * - user_mode(_regs) returns false (always kernel mode). + * - able to use the _regs for stack trace. + */ +#ifndef arch_ftrace_fill_perf_regs +/* As same as perf_arch_fetch_caller_regs(), do nothing by default */ +#define arch_ftrace_fill_perf_regs(fregs, _regs) do {} while (0) +#endif + +static __always_inline struct pt_regs * +ftrace_fill_perf_regs(struct ftrace_regs *fregs, struct pt_regs *regs) +{ + arch_ftrace_fill_perf_regs(fregs, regs); + return regs; +} + +#else /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */ + +static __always_inline struct pt_regs * +ftrace_fill_perf_regs(struct ftrace_regs *fregs, struct pt_regs *regs) +{ + return &fregs->regs; +} + +#endif + /* * When true, the ftrace_regs_{get,set}_*() functions may be used on fregs. * Note: this can be true even when ftrace_get_regs() cannot provide a pt_regs.