On Fri, May 03, 2024 at 02:01:33PM +0100, Joey Gouly wrote:
> If a memory fault occurs that is due to an overlay/pkey fault, report that to
> userspace with a SEGV_PKUERR.
>
> Signed-off-by: Joey Gouly <joey.gouly@xxxxxxx>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Will Deacon <will@xxxxxxxxxx>
> ---
> arch/arm64/include/asm/traps.h | 1 +
> arch/arm64/kernel/traps.c | 12 ++++++--
> arch/arm64/mm/fault.c | 56 ++++++++++++++++++++++++++++++++--
> 3 files changed, 64 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm64/include/asm/traps.h b/arch/arm64/include/asm/traps.h
> index eefe766d6161..f6f6f2cb7f10 100644
> --- a/arch/arm64/include/asm/traps.h
> +++ b/arch/arm64/include/asm/traps.h
> @@ -25,6 +25,7 @@ try_emulate_armv8_deprecated(struct pt_regs *regs, u32 insn)
> void force_signal_inject(int signal, int code, unsigned long address, unsigned long err);
> void arm64_notify_segfault(unsigned long addr);
> void arm64_force_sig_fault(int signo, int code, unsigned long far, const char *str);
> +void arm64_force_sig_fault_pkey(int signo, int code, unsigned long far, const char *str, int pkey);
> void arm64_force_sig_mceerr(int code, unsigned long far, short lsb, const char *str);
> void arm64_force_sig_ptrace_errno_trap(int errno, unsigned long far, const char *str);
>
> diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
> index 215e6d7f2df8..1bac6c84d3f5 100644
> --- a/arch/arm64/kernel/traps.c
> +++ b/arch/arm64/kernel/traps.c
> @@ -263,16 +263,24 @@ static void arm64_show_signal(int signo, const char *str)
> __show_regs(regs);
> }
>
> -void arm64_force_sig_fault(int signo, int code, unsigned long far,
> - const char *str)
> +void arm64_force_sig_fault_pkey(int signo, int code, unsigned long far,
> + const char *str, int pkey)
> {
> arm64_show_signal(signo, str);
> if (signo == SIGKILL)
> force_sig(SIGKILL);
> + else if (code == SEGV_PKUERR)
> + force_sig_pkuerr((void __user *)far, pkey);
Is signo definitely SIGSEGV here? It looks to me like we can get in
here for SIGBUS, SIGTRAP etc.
si_codes are not unique between different signo here, so I'm wondering
whether this should this be:
else if (signo == SIGSEGV && code == SEGV_PKUERR)
...?
> else
> force_sig_fault(signo, code, (void __user *)far);
> }
>
> +void arm64_force_sig_fault(int signo, int code, unsigned long far,
> + const char *str)
> +{
> + arm64_force_sig_fault_pkey(signo, code, far, str, 0);
Is there a reason not to follow the same convention as elsewhere, where
-1 is passed for "no pkey"?
If we think this should never be called with signo == SIGSEGV &&
code == SEGV_PKUERR and no valid pkey but if it's messy to prove, then
maybe a WARN_ON_ONCE() would be worth it here?
[...]
Cheers
---Dave
