| Message ID | 20241209105237.10498-1-o451686892@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | kselftest/arm64: abi: fix SVCR detection | expand |
On Mon, Dec 9, 2024 at 8:36 PM Mark Brown <broonie@kernel.org> wrote: > > On Mon, Dec 09, 2024 at 06:52:37PM +0800, Weizhao Ouyang wrote: > > > When using svcr_in to check ZA and Streaming Mode, we should make sure > > that the value in x2 is correct, otherwise it may trigger an Illegal > > instruction if FEAT_SVE and !FEAT_SME. > > > // Set SVCR if we're doing SME > > - cbz x1, 1f > > adrp x2, svcr_in > > ldr x2, [x2, :lo12:svcr_in] > > + cbz x1, 1f > > msr S3_3_C4_C2_2, x2 > > This is against an older verison of the code so wouldn't apply now. > It's not also checking the value of SVCR, this is checking the SME flag > passed in via x1. You can see that the SVCR value is loaded into x2 but > the check is against x1. Hi Mark, This patch aims to fix the second check (SVCR_ZA_SHIFT) instead of the first one (the x1 SME flag you're referring to): // Load ZA and ZT0 if enabled - uses x12 as scratch due to SME LDR tbz x2, #SVCR_ZA_SHIFT, 1f mov w12, #0 ldr x2, =za_in 2: _ldr_za 12, 2 If SME disabled, x2 will not have an expected value. BR, Weizhao
On Mon, Dec 9, 2024 at 9:12 PM Mark Brown <broonie@kernel.org> wrote: > > On Mon, Dec 09, 2024 at 08:51:28PM +0800, Weizhao Ouyang wrote: > > On Mon, Dec 9, 2024 at 8:36 PM Mark Brown <broonie@kernel.org> wrote: > > > > > // Set SVCR if we're doing SME > > > > - cbz x1, 1f > > > > adrp x2, svcr_in > > > > ldr x2, [x2, :lo12:svcr_in] > > > > + cbz x1, 1f > > > > msr S3_3_C4_C2_2, x2 > > > > This is against an older verison of the code so wouldn't apply now. > > > It's not also checking the value of SVCR, this is checking the SME flag > > > the check is against x1. > > > This patch aims to fix the second check (SVCR_ZA_SHIFT) instead of > > the first one (the x1 SME flag you're referring to): > > If we don't have SME we should be skipping over all the SME code and > never even looking at the value of SVCR. Looking at the current version > of the code it does that, it branches to check_sve_in if SME is not > enabled. Hi Mark, Yes we should skip it, this is just a minor tweak based on the current implementation, after all, we manually passed its value by svcr_in. Which latest code version are you referring to? I think check_sve_in is in fp testcase, not in the abi testcase. (checked the -next tree) BR, Weizhao
diff --git a/tools/testing/selftests/arm64/abi/syscall-abi-asm.S b/tools/testing/selftests/arm64/abi/syscall-abi-asm.S index df3230fdac39..98cde4f37abf 100644 --- a/tools/testing/selftests/arm64/abi/syscall-abi-asm.S +++ b/tools/testing/selftests/arm64/abi/syscall-abi-asm.S @@ -81,9 +81,9 @@ do_syscall: stp x27, x28, [sp, #96] // Set SVCR if we're doing SME - cbz x1, 1f adrp x2, svcr_in ldr x2, [x2, :lo12:svcr_in] + cbz x1, 1f msr S3_3_C4_C2_2, x2 1:
When using svcr_in to check ZA and Streaming Mode, we should make sure that the value in x2 is correct, otherwise it may trigger an Illegal instruction if FEAT_SVE and !FEAT_SME. Fixes: 43e3f85523e4 ("kselftest/arm64: Add SME support to syscall ABI test") Signed-off-by: Weizhao Ouyang <o451686892@gmail.com> --- tools/testing/selftests/arm64/abi/syscall-abi-asm.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)