On Tue, 05 May 2020 15:43:55 +0200 Thomas Gleixner <[email protected]> wrote:
> This is called from deep entry ASM in a situation where instrumentation > will cause more harm than providing useful information. > > Signed-off-by: Thomas Gleixner <[email protected]> Looks good to me. Reviewed-by: Masami Hiramatsu <[email protected]> Thank you, > --- > arch/x86/kernel/traps.c | 16 +++++++++------- > 1 file changed, 9 insertions(+), 7 deletions(-) > > --- a/arch/x86/kernel/traps.c > +++ b/arch/x86/kernel/traps.c > @@ -621,7 +621,7 @@ struct bad_iret_stack { > struct pt_regs regs; > }; > > -asmlinkage __visible notrace > +asmlinkage __visible noinstr > struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s) > { > /* > @@ -632,19 +632,21 @@ struct bad_iret_stack *fixup_bad_iret(st > * just below the IRET frame) and we want to pretend that the > * exception came from the IRET target. > */ > - struct bad_iret_stack *new_stack = > - (struct bad_iret_stack *)this_cpu_read(cpu_tss_rw.x86_tss.sp0) > - 1; > + struct bad_iret_stack tmp, *new_stack = > + (struct bad_iret_stack > *)__this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1; > > - /* Copy the IRET target to the new stack. */ > - memmove(&new_stack->regs.ip, (void *)s->regs.sp, 5*8); > + /* Copy the IRET target to the temporary storage. */ > + memcpy(&tmp.regs.ip, (void *)s->regs.sp, 5*8); > > /* Copy the remainder of the stack from the current stack. */ > - memmove(new_stack, s, offsetof(struct bad_iret_stack, regs.ip)); > + memcpy(&tmp, s, offsetof(struct bad_iret_stack, regs.ip)); > + > + /* Update the entry stack */ > + memcpy(new_stack, &tmp, sizeof(tmp)); > > BUG_ON(!user_mode(&new_stack->regs)); > return new_stack; > } > -NOKPROBE_SYMBOL(fixup_bad_iret); > #endif > > static bool is_sysenter_singlestep(struct pt_regs *regs) > -- Masami Hiramatsu <[email protected]>
