| Message ID | 20201203073458.2675400-1-pcc@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: mte: remove an ISB on kernel exit | expand |
On Wed, Dec 02, 2020 at 11:34:58PM -0800, Peter Collingbourne wrote: > This ISB is unnecessary because we will soon do an ERET. > > Signed-off-by: Peter Collingbourne <pcc@google.com> > Link: https://linux-review.googlesource.com/id/I69f1ee6bb09b1372dd744a0e01cedaf090c8d448 > --- > arch/arm64/kernel/entry.S | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S > index 07646ef4f184..f8ad8d7fb1a2 100644 > --- a/arch/arm64/kernel/entry.S > +++ b/arch/arm64/kernel/entry.S > @@ -182,7 +182,6 @@ alternative_else_nop_endif > mrs_s \tmp2, SYS_GCR_EL1 > bfi \tmp2, \tmp, #0, #16 > msr_s SYS_GCR_EL1, \tmp2 > - isb > #endif > .endm > > @@ -194,6 +193,7 @@ alternative_else_nop_endif > ldr_l \tmp, gcr_kernel_excl > > mte_set_gcr \tmp, \tmp2 > + isb > 1: > #endif > .endm It makes sense. I'll apply it after -rc1 once the MTE+kasan patches go in. Thanks.
On Wed, 2 Dec 2020 23:34:58 -0800, Peter Collingbourne wrote:
> This ISB is unnecessary because we will soon do an ERET.
Applied to arm64 (for-next/fixes), thanks!
[1/1] arm64: mte: remove an ISB on kernel exit
https://git.kernel.org/arm64/c/b614231dec78
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 07646ef4f184..f8ad8d7fb1a2 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -182,7 +182,6 @@ alternative_else_nop_endif mrs_s \tmp2, SYS_GCR_EL1 bfi \tmp2, \tmp, #0, #16 msr_s SYS_GCR_EL1, \tmp2 - isb #endif .endm @@ -194,6 +193,7 @@ alternative_else_nop_endif ldr_l \tmp, gcr_kernel_excl mte_set_gcr \tmp, \tmp2 + isb 1: #endif .endm
This ISB is unnecessary because we will soon do an ERET. Signed-off-by: Peter Collingbourne <pcc@google.com> Link: https://linux-review.googlesource.com/id/I69f1ee6bb09b1372dd744a0e01cedaf090c8d448 --- arch/arm64/kernel/entry.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)