H. Peter, Can you give me your acked-by for this?
Thanks, -- Steve On Mon, 27 Oct 2014 14:27:04 -0400 Steven Rostedt <[email protected]> wrote: > From: "Steven Rostedt (Red Hat)" <[email protected]> > > The file /sys/kernel/debug/tracing/eneabled_functions is used to debug > ftrace function hooks. Add to the output what function is being called > by the trampoline if the arch supports it. > > Add support for this feature in x86_64. > > Cc: H. Peter Anvin <[email protected]> > Signed-off-by: Steven Rostedt <[email protected]> > --- > arch/x86/kernel/ftrace.c | 98 > ++++++++++++++++++++++++++++++++++++++++++------ > kernel/trace/ftrace.c | 22 ++++++++++- > 2 files changed, 106 insertions(+), 14 deletions(-) > > diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c > index e4d48f6cad86..ca17c20a1010 100644 > --- a/arch/x86/kernel/ftrace.c > +++ b/arch/x86/kernel/ftrace.c > @@ -48,7 +48,7 @@ int ftrace_arch_code_modify_post_process(void) > union ftrace_code_union { > char code[MCOUNT_INSN_SIZE]; > struct { > - char e8; > + unsigned char e8; > int offset; > } __attribute__((packed)); > }; > @@ -797,12 +797,26 @@ static unsigned long create_trampoline(struct > ftrace_ops *ops) > return (unsigned long)trampoline; > } > > +static unsigned long calc_trampoline_call_offset(bool save_regs) > +{ > + unsigned long start_offset; > + unsigned long call_offset; > + > + if (save_regs) { > + start_offset = (unsigned long)ftrace_regs_caller; > + call_offset = (unsigned long)ftrace_regs_call; > + } else { > + start_offset = (unsigned long)ftrace_caller; > + call_offset = (unsigned long)ftrace_call; > + } > + > + return call_offset - start_offset; > +} > + > void arch_ftrace_update_trampoline(struct ftrace_ops *ops) > { > ftrace_func_t func; > unsigned char *new; > - unsigned long start_offset; > - unsigned long call_offset; > unsigned long offset; > unsigned long ip; > int ret; > @@ -820,15 +834,7 @@ void arch_ftrace_update_trampoline(struct ftrace_ops > *ops) > return; > } > > - if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) { > - start_offset = (unsigned long)ftrace_regs_caller; > - call_offset = (unsigned long)ftrace_regs_call; > - } else { > - start_offset = (unsigned long)ftrace_caller; > - call_offset = (unsigned long)ftrace_call; > - } > - > - offset = call_offset - start_offset; > + offset = calc_trampoline_call_offset(ops->flags & > FTRACE_OPS_FL_SAVE_REGS); > ip = ops->trampoline + offset; > > func = ftrace_ops_get_func(ops); > @@ -840,6 +846,74 @@ void arch_ftrace_update_trampoline(struct ftrace_ops > *ops) > /* The update should never fail */ > WARN_ON(ret); > } > + > +/* Return the address of the function the trampoline calls */ > +static void *addr_from_call(void *ptr) > +{ > + union ftrace_code_union calc; > + int ret; > + > + ret = probe_kernel_read(&calc, ptr, MCOUNT_INSN_SIZE); > + if (WARN_ON_ONCE(ret < 0)) > + return NULL; > + > + /* Make sure this is a call */ > + if (WARN_ON_ONCE(calc.e8 != 0xe8)) { > + pr_warn("Expected e8, got %x\n", calc.e8); > + return NULL; > + } > + > + return ptr + MCOUNT_INSN_SIZE + calc.offset; > +} > + > +void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, > + unsigned long frame_pointer); > + > +/* > + * If the ops->trampoline was not allocated, then it probably > + * has a static trampoline func, or is the ftrace caller itself. > + */ > +static void *static_tramp_func(struct ftrace_ops *ops, struct dyn_ftrace > *rec) > +{ > + unsigned long offset; > + bool save_regs = rec->flags & FTRACE_FL_REGS_EN; > + void *ptr; > + > + if (ops && ops->trampoline) { > +#ifdef CONFIG_FUNCTION_GRAPH_TRACER > + /* > + * We only know about function graph tracer setting as static > + * trampoline. > + */ > + if (ops->trampoline == FTRACE_GRAPH_ADDR) > + return (void *)prepare_ftrace_return; > +#endif > + return NULL; > + } > + > + offset = calc_trampoline_call_offset(save_regs); > + > + if (save_regs) > + ptr = (void *)FTRACE_REGS_ADDR + offset; > + else > + ptr = (void *)FTRACE_ADDR + offset; > + > + return addr_from_call(ptr); > +} > + > +void *arch_ftrace_trampoline_func(struct ftrace_ops *ops, struct dyn_ftrace > *rec) > +{ > + unsigned long offset; > + > + /* If we didn't allocate this trampoline, consider it static */ > + if (!ops || !(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP)) > + return static_tramp_func(ops, rec); > + > + offset = calc_trampoline_call_offset(ops->flags & > FTRACE_OPS_FL_SAVE_REGS); > + return addr_from_call((void *)ops->trampoline + offset); > +} > + > + > #endif /* CONFIG_X86_64 */ > #endif /* CONFIG_DYNAMIC_FTRACE */ > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index 15f85eac7e95..422e1f8300b1 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -2952,6 +2952,22 @@ static void t_stop(struct seq_file *m, void *p) > mutex_unlock(&ftrace_lock); > } > > +void * __weak > +arch_ftrace_trampoline_func(struct ftrace_ops *ops, struct dyn_ftrace *rec) > +{ > + return NULL; > +} > + > +static void add_trampoline_func(struct seq_file *m, struct ftrace_ops *ops, > + struct dyn_ftrace *rec) > +{ > + void *ptr; > + > + ptr = arch_ftrace_trampoline_func(ops, rec); > + if (ptr) > + seq_printf(m, " ->%pS", ptr); > +} > + > static int t_show(struct seq_file *m, void *v) > { > struct ftrace_iterator *iter = m->private; > @@ -2975,19 +2991,21 @@ static int t_show(struct seq_file *m, void *v) > > seq_printf(m, "%ps", (void *)rec->ip); > if (iter->flags & FTRACE_ITER_ENABLED) { > + struct ftrace_ops *ops = NULL; > + > seq_printf(m, " (%ld)%s", > ftrace_rec_count(rec), > rec->flags & FTRACE_FL_REGS ? " R" : " "); > if (rec->flags & FTRACE_FL_TRAMP_EN) { > - struct ftrace_ops *ops; > - > ops = ftrace_find_tramp_ops_any(rec); > if (ops) > seq_printf(m, "\ttramp: %pS", > (void *)ops->trampoline); > else > seq_printf(m, "\ttramp: ERROR!"); > + > } > + add_trampoline_func(m, ops, rec); > } > > seq_printf(m, "\n"); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
