[PATCH] kselftest/arm64: Copy whole EXTRA context

[PATCH] kselftest/arm64: Copy whole EXTRA context

[Mark Brown]

When copying the EXTRA context our calculation of the amount of data we
need to copy is incorrect, we only calculate the amount of data needed
within uc_mcontext.__reserved, not taking account of the fixed portion
of the context. Add in the offset of the reserved data so that we copy
everything we should.

This will only cause test failures in cases where the last context in the
EXTRA context is smaller than the missing data since we don't currently
validate any of the register data and all the buffers we copy into are
statically allocated so default to zero meaning that if we walk beyond the
end of what we copied we'll encounter what looks like a context with magic
and length both 0 which is a valid terminator record.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
 tools/testing/selftests/arm64/signal/test_signals_utils.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.c b/tools/testing/selftests/arm64/signal/test_signals_utils.c
index 308e229e58ab..746a4f70f082 100644
--- a/tools/testing/selftests/arm64/signal/test_signals_utils.c
+++ b/tools/testing/selftests/arm64/signal/test_signals_utils.c
@@ -192,8 +192,10 @@ static bool handle_signal_copyctx(struct tdescr *td,
 		 * in the copy, this was previously validated in
 		 * ASSERT_GOOD_CONTEXT().
 		 */
-		to_copy = offset + sizeof(struct extra_context) + 16 +
-			extra->size;
+		to_copy = __builtin_offsetof(ucontext_t,
+					     uc_mcontext.__reserved);
+		to_copy += offset + sizeof(struct extra_context) + 16;
+		to_copy += extra->size;
 		copied_extra = (struct extra_context *)&(td->live_uc->uc_mcontext.__reserved[offset]);
 	} else {
 		copied_extra = NULL;

---
base-commit: b7bfaa761d760e72a969d116517eaa12e404c262
change-id: 20230201-arm64-kselftest-full-extra-164baae78412

Best regards,
-- 
Mark Brown <broonie@kernel.org>

[PATCH] kselftest/arm64: Copy whole EXTRA context

[Mark Brown]

When copying the EXTRA context our calculation of the amount of data we
need to copy is incorrect, we only calculate the amount of data needed
within uc_mcontext.__reserved, not taking account of the fixed portion
of the context. Add in the offset of the reserved data so that we copy
everything we should.

This will only cause test failures in cases where the last context in the
EXTRA context is smaller than the missing data since we don't currently
validate any of the register data and all the buffers we copy into are
statically allocated so default to zero meaning that if we walk beyond the
end of what we copied we'll encounter what looks like a context with magic
and length both 0 which is a valid terminator record.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
 tools/testing/selftests/arm64/signal/test_signals_utils.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.c b/tools/testing/selftests/arm64/signal/test_signals_utils.c
index 308e229e58ab..746a4f70f082 100644
--- a/tools/testing/selftests/arm64/signal/test_signals_utils.c
+++ b/tools/testing/selftests/arm64/signal/test_signals_utils.c
@@ -192,8 +192,10 @@ static bool handle_signal_copyctx(struct tdescr *td,
 		 * in the copy, this was previously validated in
 		 * ASSERT_GOOD_CONTEXT().
 		 */
-		to_copy = offset + sizeof(struct extra_context) + 16 +
-			extra->size;
+		to_copy = __builtin_offsetof(ucontext_t,
+					     uc_mcontext.__reserved);
+		to_copy += offset + sizeof(struct extra_context) + 16;
+		to_copy += extra->size;
 		copied_extra = (struct extra_context *)&(td->live_uc->uc_mcontext.__reserved[offset]);
 	} else {
 		copied_extra = NULL;

---
base-commit: b7bfaa761d760e72a969d116517eaa12e404c262
change-id: 20230201-arm64-kselftest-full-extra-164baae78412

Best regards,
-- 
Mark Brown <broonie@kernel.org>


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Re: [PATCH] kselftest/arm64: Copy whole EXTRA context

[Catalin Marinas]

On Thu, 02 Feb 2023 17:30:44 +0000, Mark Brown wrote:
> When copying the EXTRA context our calculation of the amount of data we
> need to copy is incorrect, we only calculate the amount of data needed
> within uc_mcontext.__reserved, not taking account of the fixed portion
> of the context. Add in the offset of the reserved data so that we copy
> everything we should.
> 
> This will only cause test failures in cases where the last context in the
> EXTRA context is smaller than the missing data since we don't currently
> validate any of the register data and all the buffers we copy into are
> statically allocated so default to zero meaning that if we walk beyond the
> end of what we copied we'll encounter what looks like a context with magic
> and length both 0 which is a valid terminator record.
> 
> [...]

Applied to arm64 (for-next/kselftest), thanks!

[1/1] kselftest/arm64: Copy whole EXTRA context
      https://git.kernel.org/arm64/c/6012b8202022

-- 
Catalin

Re: [PATCH] kselftest/arm64: Copy whole EXTRA context

[Catalin Marinas]

On Thu, 02 Feb 2023 17:30:44 +0000, Mark Brown wrote:
> When copying the EXTRA context our calculation of the amount of data we
> need to copy is incorrect, we only calculate the amount of data needed
> within uc_mcontext.__reserved, not taking account of the fixed portion
> of the context. Add in the offset of the reserved data so that we copy
> everything we should.
> 
> This will only cause test failures in cases where the last context in the
> EXTRA context is smaller than the missing data since we don't currently
> validate any of the register data and all the buffers we copy into are
> statically allocated so default to zero meaning that if we walk beyond the
> end of what we copied we'll encounter what looks like a context with magic
> and length both 0 which is a valid terminator record.
> 
> [...]

Applied to arm64 (for-next/kselftest), thanks!

[1/1] kselftest/arm64: Copy whole EXTRA context
      https://git.kernel.org/arm64/c/6012b8202022

-- 
Catalin


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