linux-kernel - [PATCH 1/6] kselftest/arm64: Correct misleading comments on fp-stress irritators

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Message-Id: <20241023-arm64-fp-stress-irritator-v1-1-a51af298d449@kernel.org>
Date: Wed, 23 Oct 2024 21:38:29 +0100
From: Mark Brown <broonie@...nel.org>
To: Catalin Marinas <catalin.marinas@....com>, 
 Will Deacon <will@...nel.org>, Shuah Khan <shuah@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>, 
 linux-arm-kernel@...ts.infradead.org, linux-kselftest@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Mark Brown <broonie@...nel.org>
Subject: [PATCH 1/6] kselftest/arm64: Correct misleading comments on
 fp-stress irritators

The comments in the handlers for the irritator signal in the test threads
for fp-stress suggest that the irritator will corrupt the register state
observed by the main thread but this is not the case, instead the FPSIMD
and SVE irritators (which are the only ones that are implemented) modify
the current register state which is expected to be overwritten on return
from the handler by the saved register state. Update the comment to reflect
what the handler is actually doing.

Signed-off-by: Mark Brown <broonie@...nel.org>
---
 tools/testing/selftests/arm64/fp/fpsimd-test.S | 3 +--
 tools/testing/selftests/arm64/fp/sve-test.S    | 3 +--
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/arm64/fp/fpsimd-test.S b/tools/testing/selftests/arm64/fp/fpsimd-test.S
index 8b960d01ed2e0ef516893b68794078ddf8c01e1f..bdfb7cf2e4ec175fda62c1c2f38c6ebb1a1c48bf 100644
--- a/tools/testing/selftests/arm64/fp/fpsimd-test.S
+++ b/tools/testing/selftests/arm64/fp/fpsimd-test.S
@@ -134,8 +134,7 @@ function check_vreg
 	b	memcmp
 endfunction
 
-// Any SVE register modified here can cause corruption in the main
-// thread -- but *only* the registers modified here.
+// Modify live register state, the signal return will undo our changes
 function irritator_handler
 	// Increment the irritation signal count (x23):
 	ldr	x0, [x2, #ucontext_regs + 8 * 23]
diff --git a/tools/testing/selftests/arm64/fp/sve-test.S b/tools/testing/selftests/arm64/fp/sve-test.S
index fff60e2a25addfd4850ef71aa3cf6535ac880ffd..e3c0d585684df29723a49265f3df6d23817498c7 100644
--- a/tools/testing/selftests/arm64/fp/sve-test.S
+++ b/tools/testing/selftests/arm64/fp/sve-test.S
@@ -291,8 +291,7 @@ function check_ffr
 #endif
 endfunction
 
-// Any SVE register modified here can cause corruption in the main
-// thread -- but *only* the registers modified here.
+// Modify live register state, the signal return will undo our changes
 function irritator_handler
 	// Increment the irritation signal count (x23):
 	ldr	x0, [x2, #ucontext_regs + 8 * 23]

-- 
2.39.2