On Thu, 12 Nov 2020 09:21:44 +0100
Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> On Wed, Nov 11, 2020 at 08:15:19PM -0500, Steven Rostedt wrote:
>
> > diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
> > index e00fe88146e0..235385a38bd9 100644
> > --- a/arch/x86/include/asm/ftrace.h
> > +++ b/arch/x86/include/asm/ftrace.h
> > @@ -54,6 +54,9 @@ arch_ftrace_get_regs(struct ftrace_regs *fregs)
> > return NULL;
> > return &fregs->regs;
> > }
> > +
> > +#define ftrace_regs_set_ip(fregs, _ip) \
> > + do { (fregs)->regs.ip = (_ip); } while (0)
> > #endif
> >
> > #ifdef CONFIG_DYNAMIC_FTRACE
> > diff --git a/arch/x86/include/asm/livepatch.h b/arch/x86/include/asm/livepatch.h
> > index 1fde1ab6559e..59a08d5c6f1d 100644
> > --- a/arch/x86/include/asm/livepatch.h
> > +++ b/arch/x86/include/asm/livepatch.h
> > @@ -12,9 +12,9 @@
> > #include <asm/setup.h>
> > #include <linux/ftrace.h>
> >
> > -static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip)
> > +static inline void klp_arch_set_pc(struct ftrace_regs *fregs, unsigned long ip)
> > {
> > - regs->ip = ip;
> > + ftrace_regs_set_ip(fregs, ip);
> > }
> >
>
> The normal variant is called instruction_pointer_set(), should this be
> called ftrace_instruction_pointer_set() ?
Sure, I can change that.
>
> (and yes, I hate the long name too).
ftrace_regs_ip_set()? ;-)
>
> Also, do you want something like:
>
> unsigned long ftrace_regs_get_register(struct ftrace_regs *regs, unsigned int offset)
> {
I haven't gotten this far yet. I'm looking at generic use cases on how to
get args across archs. Each arch will have its own method.
> switch (offset / sizeof(long)) {
> case 4: /* RBP */
>
> case 8: /* R9 */
> case 9: /* R8 */
> case 10: /* RAX */
> case 11: /* RCX */
> case 12: /* RDX */
> case 13: /* RSI */
> case 14: /* RDI */
> case 15: /* ORIG_RAX */
> case 16: /* RIP */
> return *(unsigned long *)regs->regs + offset;
>
> default:
> WARN_ON_ONCE(1);
Not sure we even want to warn. Perhaps have this as:
bool ftrace_regs_get_register(struct ftrace_regs *regs,
unsigned int offset, unsigned long *val)
{
if (regs->cs) {
*val = regs_get_register(regs->regs, offset);
return true;
}
switch (offset / sizeof(long)) {
case ...:
*val = *(unsigned long *)regs->regs + offset;
return true;
default;
return false;
> }
-- Steve
