What a difference one character makes :-)
--
Nadav Har'El
n...@scylladb.com
On Tue, Aug 30, 2022 at 6:59 PM Commit Bot <b...@cloudius-systems.com> wrote:
> From: Waldemar Kozaczuk <jwkozac...@gmail.com>
> Committer: Waldemar Kozaczuk <jwkozac...@gmail.com>
> Branch: master
>
> aarch64 trace: make compiler pick a register instead of x0
>
> This subtle 1-character patch fixes a nasty bug that causes interrupts
> to be enabled instead of correctly restored to the state it was when
> saving the state. This bug would affect the tracing logic and result in
> crashes described by the issues #1158 and #1195.
>
> This bug in inline assembly was most likely a typo as I am sure
> the intention was to use '%0' instead of 'x0' to let compiler
> correctly pick a register instead of using any garbage in the x0
> register.
>
> Fixes #1158
> Fixes #1195
>
> Signed-off-by: Waldemar Kozaczuk <jwkozac...@gmail.com>
>
> ---
> diff --git a/arch/aarch64/arch.hh b/arch/aarch64/arch.hh
> --- a/arch/aarch64/arch.hh
> +++ b/arch/aarch64/arch.hh
> @@ -79,7 +79,7 @@ inline void irq_flag_notrace::save() {
> }
>
> inline void irq_flag_notrace::restore() {
> - asm volatile("msr daif, x0" :: "r"(daif) : "memory");
> + asm volatile("msr daif, %0" :: "r"(daif) : "memory");
> }
>
> inline bool irq_flag_notrace::enabled() const {
>
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