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SubjectRe: [PATCH v5 2/4] x86/traps: Print address on #GP
On Thu, Nov 28, 2019 at 12:49:14AM +0100, Jann Horn wrote:

With a few nits below,

Reviewed-and-tested-by: Sean Christopherson <sean.j.christopherson@intel.com>

> +#define GPFSTR "general protection fault"
> +
> dotraplinkage void
> do_general_protection(struct pt_regs *regs, long error_code)
> {
> - const char *desc = "general protection fault";
> struct task_struct *tsk;
> + char desc[sizeof(GPFSTR) + 50 + 2*sizeof(unsigned long) + 1] = GPFSTR;

Nit, x86 maintainers prefer inverse fir tree for variable declarations.

>
> RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
> cond_local_irq_enable(regs);
> @@ -540,6 +587,9 @@ do_general_protection(struct pt_regs *regs, long error_code)
>
> tsk = current;
> if (!user_mode(regs)) {
> + enum kernel_gp_hint hint = GP_NO_HINT;
> + unsigned long gp_addr;
> +
> if (fixup_exception(regs, X86_TRAP_GP, error_code, 0))
> return;
>
> @@ -556,8 +606,22 @@ do_general_protection(struct pt_regs *regs, long error_code)
> return;
>
> if (notify_die(DIE_GPF, desc, regs, error_code,
> - X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP)
> - die(desc, regs, error_code);
> + X86_TRAP_GP, SIGSEGV) == NOTIFY_STOP)
> + return;
> +
> + if (error_code)
> + snprintf(desc, sizeof(desc), "segment-related " GPFSTR);
> + else
> + hint = get_kernel_gp_address(regs, &gp_addr);
> +
> + if (hint != GP_NO_HINT)
> + snprintf(desc, sizeof(desc), GPFSTR " %s 0x%lx",

Nit, probably should have a comma before the hint, i.e. GPFSTR ", %s...".

general protection fault maybe for address 0xffffc9000017cf58: 0000 [#1] SMP
general protection fault probably for non-canonical address 0xdead000000000000: 0000 [#1] SMP

vs.

general protection fault, maybe for address 0xffffc9000017cf58: 0000 [#1] SMP
general protection fault, probably for non-canonical address 0xdead000000000000: 0000 [#1] SMP

> + (hint == GP_NON_CANONICAL) ?
> + "probably for non-canonical address" :
> + "maybe for address",
> + gp_addr);
> +
> + die(desc, regs, error_code);
> return;
> }
>
> --
> 2.24.0.432.g9d3f5f5b63-goog
>

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