Re: [PATCH 5.15 000/923] 5.15.3-rc3 review

On Thu, Nov 18, 2021 at 10:39:44AM +0100, Peter Zijlstra wrote:

@@ -396,22 +416,27 @@ static bool deref_stack_iret_regs(struct unwind_state *state, unsigned long addr static bool get_reg(struct unwind_state *state, unsigned int reg_off, unsigned long *val) {

• unsigned int reg = reg_off/8;
• if (!state->regs) return false;

• pagefault_disable(); if (state->full_regs) {

• *val = READ_ONCE_NOCHECK(((unsigned long *)state->regs)[reg]);
  

• __get_kernel_nofault(val, (void *)state->regs + reg_off, unsigned long, Efault);
  

• pagefault_enable();
  

  return true; }

if (state->prev_regs) {

• *val = READ_ONCE_NOCHECK(((unsigned long *)state->prev_regs)[reg]);
  

• __get_kernel_nofault(val, (void *)state->regs + reg_off, unsigned long, Efault);
  

^^^ prev_regs

• pagefault_enable();
  

  return true; }

return false;

+Efault:

• pagefault_enable();
• return false;

}