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    SubjectRe: [PATCH v21 06/26] x86/cet: Add control-protection fault handler
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    On 2/24/2021 8:13 AM, Borislav Petkov wrote:
    > On Wed, Feb 17, 2021 at 02:27:10PM -0800, Yu-cheng Yu wrote:
    >> +/*
    >> + * When a control protection exception occurs, send a signal to the responsible
    >> + * application. Currently, control protection is only enabled for user mode.
    >> + * This exception should not come from kernel mode.
    >> + */
    >> +DEFINE_IDTENTRY_ERRORCODE(exc_control_protection)
    >> +{
    >> + static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL,
    >> + DEFAULT_RATELIMIT_BURST);

    [...]

    >> +
    >> + rdmsrl(MSR_IA32_PL3_SSP, ssp);
    >> + pr_emerg("%s[%d] control protection ip:%lx sp:%lx ssp:%lx error:%lx(%s)",
    >> + tsk->comm, task_pid_nr(tsk),
    >> + regs->ip, regs->sp, ssp, error_code,
    >> + control_protection_err[err]);
    >> + print_vma_addr(KERN_CONT " in ", regs->ip);
    >> + pr_cont("\n");
    >> + }
    >> +
    >> + force_sig_fault(SIGSEGV, SEGV_CPERR,
    >> + (void __user *)uprobe_get_trap_addr(regs));
    >
    > Why is this calling an uprobes function?
    >

    I will change it to error_get_trap_addr().

    > Also, do not break that line even if it is longer than 80.
    >
    >> + cond_local_irq_disable(regs);
    >> +}
    >> +#endif
    >> +
    >> static bool do_int3(struct pt_regs *regs)
    >> {
    >> int res;
    >> diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
    >> index d2597000407a..1c2ea91284a0 100644
    >> --- a/include/uapi/asm-generic/siginfo.h
    >> +++ b/include/uapi/asm-generic/siginfo.h
    >> @@ -231,7 +231,8 @@ typedef struct siginfo {
    >> #define SEGV_ADIPERR 7 /* Precise MCD exception */
    >> #define SEGV_MTEAERR 8 /* Asynchronous ARM MTE error */
    >> #define SEGV_MTESERR 9 /* Synchronous ARM MTE exception */
    >> -#define NSIGSEGV 9
    >> +#define SEGV_CPERR 10 /* Control protection fault */
    >> +#define NSIGSEGV 10
    >
    > I still don't see the patch adding this to the manpage of sigaction(2).
    >
    > There's a git repo there: https://www.kernel.org/doc/man-pages/
    >
    > and I'm pretty sure Michael takes patches.
    >

    I will send a patch.

    --
    Yu-cheng

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