Rename is_signed_type() to is_signed_var() to avoid colliding with a macro of the same name defined by linux/overflow.h. Note, overflow.h's version takes a type as the input, whereas the harness's version takes a variable!
This fixes warnings (and presumably potential test failures) in tests that utilize the selftests harness and happen to (indirectly) include overflow.h.
In file included from tools/include/linux/bits.h:34, from tools/include/linux/bitops.h:14, from tools/include/linux/hashtable.h:13, from include/kvm_util.h:11, from x86/userspace_msr_exit_test.c:11: tools/include/linux/overflow.h:31:9: error: "is_signed_type" redefined [-Werror] 31 | #define is_signed_type(type) (((type)(-1)) < (type)1) | ^~~~~~~~~~~~~~ In file included from include/kvm_test_harness.h:11, from x86/userspace_msr_exit_test.c:9: ../kselftest_harness.h:754:9: note: this is the location of the previous definition 754 | #define is_signed_type(var) (!!(((__typeof__(var))(-1)) < (__typeof__(var))1)) | ^~~~~~~~~~~~~~
Opportunistically use is_signed_type() to implement is_signed_var() so that the relationship and differences are obvious.
Fixes: fc92099902fb ("tools headers: Synchronize linux/bits.h with the kernel sources") Cc: Vincent Mailhol mailhol.vincent@wanadoo.fr Cc: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sean Christopherson seanjc@google.com ---
This is probably compile-tested only, I don't think any of the KVM selftests utilize the harness's EXPECT macros.
tools/testing/selftests/kselftest_harness.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/kselftest_harness.h b/tools/testing/selftests/kselftest_harness.h index 2925e47db995..f3e7a46345db 100644 --- a/tools/testing/selftests/kselftest_harness.h +++ b/tools/testing/selftests/kselftest_harness.h @@ -56,6 +56,7 @@ #include <asm/types.h> #include <ctype.h> #include <errno.h> +#include <linux/overflow.h> #include <linux/unistd.h> #include <poll.h> #include <stdbool.h> @@ -751,7 +752,7 @@ for (; _metadata->trigger; _metadata->trigger = \ __bail(_assert, _metadata))
-#define is_signed_type(var) (!!(((__typeof__(var))(-1)) < (__typeof__(var))1)) +#define is_signed_var(var) is_signed_type(__typeof__(var))
#define __EXPECT(_expected, _expected_str, _seen, _seen_str, _t, _assert) do { \ /* Avoid multiple evaluation of the cases */ \ @@ -759,7 +760,7 @@ __typeof__(_seen) __seen = (_seen); \ if (!(__exp _t __seen)) { \ /* Report with actual signedness to avoid weird output. */ \ - switch (is_signed_type(__exp) * 2 + is_signed_type(__seen)) { \ + switch (is_signed_var(__exp) * 2 + is_signed_var(__seen)) { \ case 0: { \ uintmax_t __exp_print = (uintmax_t)__exp; \ uintmax_t __seen_print = (uintmax_t)__seen; \
base-commit: 78f4e737a53e1163ded2687a922fce138aee73f5
On 25/06/2025 at 08:19, Sean Christopherson wrote:
Rename is_signed_type() to is_signed_var() to avoid colliding with a macro of the same name defined by linux/overflow.h. Note, overflow.h's version takes a type as the input, whereas the harness's version takes a variable!
This fixes warnings (and presumably potential test failures) in tests that utilize the selftests harness and happen to (indirectly) include overflow.h.
In file included from tools/include/linux/bits.h:34, from tools/include/linux/bitops.h:14, from tools/include/linux/hashtable.h:13, from include/kvm_util.h:11, from x86/userspace_msr_exit_test.c:11: tools/include/linux/overflow.h:31:9: error: "is_signed_type" redefined [-Werror] 31 | #define is_signed_type(type) (((type)(-1)) < (type)1) | ^~~~~~~~~~~~~~ In file included from include/kvm_test_harness.h:11, from x86/userspace_msr_exit_test.c:9: ../kselftest_harness.h:754:9: note: this is the location of the previous definition 754 | #define is_signed_type(var) (!!(((__typeof__(var))(-1)) < (__typeof__(var))1)) | ^~~~~~~~~~~~~~
Opportunistically use is_signed_type() to implement is_signed_var() so that the relationship and differences are obvious.
Fixes: fc92099902fb ("tools headers: Synchronize linux/bits.h with the kernel sources") Cc: Vincent Mailhol mailhol.vincent@wanadoo.fr Cc: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sean Christopherson seanjc@google.com
This is probably compile-tested only, I don't think any of the KVM selftests utilize the harness's EXPECT macros.
tools/testing/selftests/kselftest_harness.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/kselftest_harness.h b/tools/testing/selftests/kselftest_harness.h index 2925e47db995..f3e7a46345db 100644 --- a/tools/testing/selftests/kselftest_harness.h +++ b/tools/testing/selftests/kselftest_harness.h @@ -56,6 +56,7 @@ #include <asm/types.h> #include <ctype.h> #include <errno.h> +#include <linux/overflow.h> #include <linux/unistd.h> #include <poll.h> #include <stdbool.h> @@ -751,7 +752,7 @@ for (; _metadata->trigger; _metadata->trigger = \ __bail(_assert, _metadata)) -#define is_signed_type(var) (!!(((__typeof__(var))(-1)) < (__typeof__(var))1)) +#define is_signed_var(var) is_signed_type(__typeof__(var))
It would potentially make sense to add the is_signed_var() to overflow.h. I see a couple places doing some is_signed_type(typeof(x)):
$ git grep "is_signed_type(typeof" | wc -l 5
And I can imagine this number growing in the future.
But this is by no way a reason strong enough to block this patch. It is just a random idea I am sharing here.
So that said:
Reviewed-by: Vincent Mailhol mailhol.vincent@wanadoo.fr
#define __EXPECT(_expected, _expected_str, _seen, _seen_str, _t, _assert) do { \ /* Avoid multiple evaluation of the cases */ \ @@ -759,7 +760,7 @@ __typeof__(_seen) __seen = (_seen); \ if (!(__exp _t __seen)) { \ /* Report with actual signedness to avoid weird output. */ \
switch (is_signed_type(__exp) * 2 + is_signed_type(__seen)) { \
switch (is_signed_var(__exp) * 2 + is_signed_var(__seen)) { \base-commit: 78f4e737a53e1163ded2687a922fce138aee73f5
Yours sincerely, Vincent Mailhol
On Tue, Jun 24, 2025 at 04:19:30PM -0700, Sean Christopherson wrote:
Rename is_signed_type() to is_signed_var() to avoid colliding with a macro of the same name defined by linux/overflow.h. Note, overflow.h's version takes a type as the input, whereas the harness's version takes a variable!
Can we just update compiler.h to use typeof() and drop duplicates? (typeof() a type is a pass-thru). Totally untested:
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 6f04a1d8c720..cb925b883806 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -347,7 +347,7 @@ static inline void *offset_to_ptr(const int *off) * Whether 'type' is a signed type or an unsigned type. Supports scalar types, * bool and also pointer types. */ -#define is_signed_type(type) (((type)(-1)) < (__force type)1) +#define is_signed_type(type) (((typeof(type))(-1)) < (__force typeof(type))1) #define is_unsigned_type(type) (!is_signed_type(type))
/*
On Fri, Jun 27, 2025, Kees Cook wrote:
On Tue, Jun 24, 2025 at 04:19:30PM -0700, Sean Christopherson wrote:
Rename is_signed_type() to is_signed_var() to avoid colliding with a macro of the same name defined by linux/overflow.h. Note, overflow.h's version takes a type as the input, whereas the harness's version takes a variable!
Can we just update compiler.h to use typeof() and drop duplicates?
I have no objection to doing so, but I'd prefer any such change go on top. I'd like to get this fixed in 6.16, and as your diff alludes to, I think tools' version of compiler.h should follow the kernel's version (and presumably the below isn't an rc6+ candidate :-) ).
(typeof() a type is a pass-thru). Totally untested:
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 6f04a1d8c720..cb925b883806 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -347,7 +347,7 @@ static inline void *offset_to_ptr(const int *off)
- Whether 'type' is a signed type or an unsigned type. Supports scalar types,
- bool and also pointer types.
*/ -#define is_signed_type(type) (((type)(-1)) < (__force type)1) +#define is_signed_type(type) (((typeof(type))(-1)) < (__force typeof(type))1) #define is_unsigned_type(type) (!is_signed_type(type)) /*
-- Kees Cook
On Tue, 24 Jun 2025 16:19:30 -0700, Sean Christopherson wrote:
Rename is_signed_type() to is_signed_var() to avoid colliding with a macro of the same name defined by linux/overflow.h. Note, overflow.h's version takes a type as the input, whereas the harness's version takes a variable!
This fixes warnings (and presumably potential test failures) in tests that utilize the selftests harness and happen to (indirectly) include overflow.h.
[...]
Applied to kvm-x86 fixes, as this is still a big thorn in my side.
[1/1] selftests: harness: Rework is_signed_type() to avoid collision with overflow.h https://github.com/kvm-x86/linux/commit/40d5b2ab0d72
On Tue, Jun 24, 2025 at 04:19:30PM -0700, Sean Christopherson wrote:
Rename is_signed_type() to is_signed_var() to avoid colliding with a macro of the same name defined by linux/overflow.h. Note, overflow.h's version takes a type as the input, whereas the harness's version takes a variable!
This patch is in -next and is causing widespread breakage in the selftests -next on at least arm and arm64 due to:
make --silent --keep-going --jobs=15 O=/build/stage/build-work INSTALL_PATH=/build/stage/build-work/kselftest_install ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- CROSS_COMPILE_COMPAT=arm-linux-gnueabihf- kselftest-install
...
In file included from test-pcmtest-driver.c:10: ../kselftest_harness.h:59:10: fatal error: linux/overflow.h: No such file or directory 59 | #include <linux/overflow.h> | ^~~~~~~~~~~~~~~~~~ compilation terminated.
Sample build log:
https://builds.sirena.org.uk/5303936d609e09665deda94eaedf26a0e5c3a087/arm64/...
On Wed, Aug 20, 2025, Mark Brown wrote:
On Tue, Jun 24, 2025 at 04:19:30PM -0700, Sean Christopherson wrote:
Rename is_signed_type() to is_signed_var() to avoid colliding with a macro of the same name defined by linux/overflow.h. Note, overflow.h's version takes a type as the input, whereas the harness's version takes a variable!
This patch is in -next and is causing widespread breakage in the selftests -next on at least arm and arm64 due to:
make --silent --keep-going --jobs=15 O=/build/stage/build-work INSTALL_PATH=/build/stage/build-work/kselftest_install ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- CROSS_COMPILE_COMPAT=arm-linux-gnueabihf- kselftest-install
...
In file included from test-pcmtest-driver.c:10: ../kselftest_harness.h:59:10: fatal error: linux/overflow.h: No such file or directory 59 | #include <linux/overflow.h> | ^~~~~~~~~~~~~~~~~~ compilation terminated.
Argh, many selftests don't add tools/include to their include path. The least awful thing I can think of is to go with a minimal fix to avoid the collision. AFAICT, nothing outside of kselftest_harness.h uses is_signed_type(), so this shouldn't cause a different flavor of breakage?
-- From: Sean Christopherson seanjc@google.com Date: Tue, 24 Jun 2025 16:19:30 -0700 Subject: [PATCH] selftests: harness: Rework is_signed_type() to avoid collision with overflow.h
Rename is_signed_type() to is_signed_var() to avoid colliding with a macro of the same name defined by tools' linux/overflow.h. This fixes warnings (and presumably potential test failures) in tests that utilize the selftests harness and happen to (indirectly) include overflow.h.
In file included from tools/include/linux/bits.h:34, from tools/include/linux/bitops.h:14, from tools/include/linux/hashtable.h:13, from include/kvm_util.h:11, from x86/userspace_msr_exit_test.c:11: tools/include/linux/overflow.h:31:9: error: "is_signed_type" redefined [-Werror] 31 | #define is_signed_type(type) (((type)(-1)) < (type)1) | ^~~~~~~~~~~~~~ In file included from include/kvm_test_harness.h:11, from x86/userspace_msr_exit_test.c:9: ../kselftest_harness.h:754:9: note: this is the location of the previous definition 754 | #define is_signed_type(var) (!!(((__typeof__(var))(-1)) < (__typeof__(var))1)) | ^~~~~~~~~~~~~~
Use a separate definition, at least for now, as many selftests build without tools/include in their include path.
Fixes: fc92099902fb ("tools headers: Synchronize linux/bits.h with the kernel sources") Cc: Vincent Mailhol mailhol.vincent@wanadoo.fr Cc: Arnaldo Carvalho de Melo acme@redhat.com Link: https://lore.kernel.org/r/20250624231930.583689-1-seanjc@google.com Signed-off-by: Sean Christopherson seanjc@google.com --- tools/testing/selftests/kselftest_harness.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/kselftest_harness.h b/tools/testing/selftests/kselftest_harness.h index 2925e47db995..8516e8434bc4 100644 --- a/tools/testing/selftests/kselftest_harness.h +++ b/tools/testing/selftests/kselftest_harness.h @@ -751,7 +751,7 @@ for (; _metadata->trigger; _metadata->trigger = \ __bail(_assert, _metadata))
-#define is_signed_type(var) (!!(((__typeof__(var))(-1)) < (__typeof__(var))1)) +#define is_signed_var(var) (!!(((__typeof__(var))(-1)) < (__typeof__(var))1))
#define __EXPECT(_expected, _expected_str, _seen, _seen_str, _t, _assert) do { \ /* Avoid multiple evaluation of the cases */ \ @@ -759,7 +759,7 @@ __typeof__(_seen) __seen = (_seen); \ if (!(__exp _t __seen)) { \ /* Report with actual signedness to avoid weird output. */ \ - switch (is_signed_type(__exp) * 2 + is_signed_type(__seen)) { \ + switch (is_signed_var(__exp) * 2 + is_signed_var(__seen)) { \ case 0: { \ uintmax_t __exp_print = (uintmax_t)__exp; \ uintmax_t __seen_print = (uintmax_t)__seen; \
base-commit: 923fcb3dbc0246fc5207093c0049af4c56f20e41 --
On Wed, Aug 20, 2025, Sean Christopherson wrote:
On Wed, Aug 20, 2025, Mark Brown wrote:
On Tue, Jun 24, 2025 at 04:19:30PM -0700, Sean Christopherson wrote:
Rename is_signed_type() to is_signed_var() to avoid colliding with a macro of the same name defined by linux/overflow.h. Note, overflow.h's version takes a type as the input, whereas the harness's version takes a variable!
This patch is in -next and is causing widespread breakage in the selftests -next on at least arm and arm64 due to:
make --silent --keep-going --jobs=15 O=/build/stage/build-work INSTALL_PATH=/build/stage/build-work/kselftest_install ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- CROSS_COMPILE_COMPAT=arm-linux-gnueabihf- kselftest-install
...
In file included from test-pcmtest-driver.c:10: ../kselftest_harness.h:59:10: fatal error: linux/overflow.h: No such file or directory 59 | #include <linux/overflow.h> | ^~~~~~~~~~~~~~~~~~ compilation terminated.
Argh, many selftests don't add tools/include to their include path. The least awful thing I can think of is to go with a minimal fix to avoid the collision. AFAICT, nothing outside of kselftest_harness.h uses is_signed_type(), so this shouldn't cause a different flavor of breakage?
I force-pushed a straight rename. Please holler if that somehow still breaks builds.
[1/1] selftests: harness: Rename is_signed_type() to avoid collision with overflow.h https://github.com/kvm-x86/linux/commit/dce1b33ed743
linux-kselftest-mirror@lists.linaro.org
-
Kees Cook -
Mark Brown -
Sean Christopherson -
Vincent Mailhol