On Mon, Oct 27, 2014 at 02:27:04PM -0400, Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)" <rost...@goodmis.org>
>
> 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 <h...@linux.intel.com>
> Signed-off-by: Steven Rostedt <rost...@goodmis.org>
> ---
> 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;
u8?
"u8 e8;" looks supa dupa though :-)
> 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.
> + 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! :-)
--
Regards/Gruss,
Boris.
Sent from a fat crate under my desk. Formatting is fine.
--
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
