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SubjectRe: [PATCH 3/3 v5] livepatch: Use the default ftrace_ops instead of REGS when ARGS is available
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() ?

(and yes, I hate the long name too).

Also, do you want something like:

unsigned long ftrace_regs_get_register(struct ftrace_regs *regs, unsigned int offset)
{
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);
}
return 0;
}

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