Messages in this thread | | | Date | Thu, 6 Nov 2014 09:01:57 -0500 | From | Steven Rostedt <> | Subject | Re: [for-next][PATCH 2/4] ftrace/x86: Show trampoline call function in enabled_functions |
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On Wed, 5 Nov 2014 11:42:07 +0100 Borislav Petkov <bp@alien8.de> wrote:
> > 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; > > u8? > > "u8 e8;" looks supa dupa though :-)
And compete with PowerPC's eieio command.
> > > 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); > > Simply WARN_ONCE gives you both.
Ah, could do that.
> > > + 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) > > I guess you can merge this one into its only caller below - it is not > that huge... yet! :-) >
Hmm, it's big enough not to be in that function as a if statement that will return anyway.
gcc will just make it inlined anyway. I think it's better separate for readability.
-- Steve
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