Messages in this thread | | | Date | Tue, 12 Nov 2019 13:25:36 -0500 | From | Steven Rostedt <> | Subject | Re: [PATCH -v5 05/17] x86/ftrace: Use text_poke() |
| |
On Mon, 11 Nov 2019 14:12:57 +0100 Peter Zijlstra <peterz@infradead.org> wrote:
> --- a/arch/x86/kernel/ftrace.c > +++ b/arch/x86/kernel/ftrace.c > @@ -34,6 +34,8 @@ > > #ifdef CONFIG_DYNAMIC_FTRACE > > +static int ftrace_poke_late = 0; > + > int ftrace_arch_code_modify_prepare(void) > __acquires(&text_mutex) > { > @@ -43,16 +45,15 @@ int ftrace_arch_code_modify_prepare(void > * ftrace has it set to "read/write". > */ > mutex_lock(&text_mutex); > - set_kernel_text_rw(); > - set_all_modules_text_rw(); > + ftrace_poke_late = 1; > return 0; > } > > int ftrace_arch_code_modify_post_process(void) > __releases(&text_mutex) > { > - set_all_modules_text_ro(); > - set_kernel_text_ro(); > + text_poke_finish();
Why is the text_poke_finish() needed here? Can we add a comment about why?
> + ftrace_poke_late = 0; > mutex_unlock(&text_mutex); > return 0; > } > @@ -60,67 +61,34 @@ int ftrace_arch_code_modify_post_process > union ftrace_code_union { > char code[MCOUNT_INSN_SIZE]; > struct { > - unsigned char op; > + char op; > int offset; > } __attribute__((packed)); > }; > > -static int ftrace_calc_offset(long ip, long addr) > -{ > - return (int)(addr - ip); > -} > - > -static unsigned char * > -ftrace_text_replace(unsigned char op, unsigned long ip, unsigned long addr) > +static const char *ftrace_text_replace(char op, unsigned long ip, unsigned long addr) > { > static union ftrace_code_union calc; > > - calc.op = op; > - calc.offset = ftrace_calc_offset(ip + MCOUNT_INSN_SIZE, addr); > + calc.op = op; > + calc.offset = (int)(addr - (ip + MCOUNT_INSN_SIZE)); > > return calc.code; > }
[..]
> /* Return the address of the function the trampoline calls */ > @@ -981,19 +555,18 @@ void arch_ftrace_trampoline_free(struct > #ifdef CONFIG_DYNAMIC_FTRACE > extern void ftrace_graph_call(void); > > -static unsigned char *ftrace_jmp_replace(unsigned long ip, unsigned long addr) > +static const char *ftrace_jmp_replace(unsigned long ip, unsigned long addr) > { > - return ftrace_text_replace(0xe9, ip, addr); > + return ftrace_text_replace(JMP32_INSN_OPCODE, ip, addr); > } > > static int ftrace_mod_jmp(unsigned long ip, void *func) > { > - unsigned char *new; > + const char *new; > > - ftrace_update_func_call = 0UL; > new = ftrace_jmp_replace(ip, (unsigned long)func); > - > - return update_ftrace_func(ip, new); > + text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL); // BATCH
What do you mean by "BATCH" ?
-- Steve
> + return 0; > } > > int ftrace_enable_ftrace_graph_caller(void) > @@ -1019,10 +592,9 @@ int ftrace_disable_ftrace_graph_caller(v > void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent, > unsigned long frame_pointer) > { > + unsigned long return_hooker = (unsigned long)&return_to_handler; > unsigned long old; > int faulted; > - unsigned long return_hooker = (unsigned long) > - &return_to_handler; > > /* > * When resuming from suspend-to-ram, this function can be indirectly > --- a/arch/x86/kernel/traps.c > +++ b/arch/x86/kernel/traps.c > @@ -563,15 +563,6 @@ NOKPROBE_SYMBOL(do_general_protection); > > dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code) > { > -#ifdef CONFIG_DYNAMIC_FTRACE > - /* > - * ftrace must be first, everything else may cause a recursive crash. > - * See note by declaration of modifying_ftrace_code in ftrace.c > - */ > - if (unlikely(atomic_read(&modifying_ftrace_code)) && > - ftrace_int3_handler(regs)) > - return; > -#endif > if (poke_int3_handler(regs)) > return; > >
| |