[LTP] [PATCH 0/2] __builtin___clear_cache() => __clear_cache()

[LTP] [PATCH 0/2] __builtin___clear_cache() => __clear_cache()

[Petr Vorel]

Hi,

based on Khem's report and attempt to fix

https://patchwork.ozlabs.org/project/ltp/patch/20240611055655.614782-1-raj.khem@gmail.com/
https://lore.kernel.org/ltp/20240611055655.614782-1-raj.khem@gmail.com/

Kind regards,
Petr

Petr Vorel (2):
  m4: mprotect04: Replace __builtin___clear_cache with __clear_cache
  hugemmap15: Check for __clear_cache()

 configure.ac                                  |  2 +-
 m4/ltp-builtin_clear_cache.m4                 | 19 ------------------
 m4/ltp-clear_cache.m4                         | 20 +++++++++++++++++++
 .../kernel/mem/hugetlb/hugemmap/hugemmap15.c  |  3 +++
 .../kernel/syscalls/mprotect/mprotect04.c     |  7 +++----
 5 files changed, 27 insertions(+), 24 deletions(-)
 delete mode 100644 m4/ltp-builtin_clear_cache.m4
 create mode 100644 m4/ltp-clear_cache.m4

-- 
2.51.0


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[LTP] [PATCH 1/2] m4: mprotect04: Replace __builtin___clear_cache with __clear_cache

[Petr Vorel]

__clear_cache() should be quite common now and we already use it in
hugemmap15.c. Convert autotools m4 check to detect it.

Signed-off-by: Petr Vorel <petr.vorel@gmail.com>
---
 configure.ac                                  |  2 +-
 m4/ltp-builtin_clear_cache.m4                 | 19 ------------------
 m4/ltp-clear_cache.m4                         | 20 +++++++++++++++++++
 .../kernel/syscalls/mprotect/mprotect04.c     |  7 +++----
 4 files changed, 24 insertions(+), 24 deletions(-)
 delete mode 100644 m4/ltp-builtin_clear_cache.m4
 create mode 100644 m4/ltp-clear_cache.m4

diff --git a/configure.ac b/configure.ac
index 0480f46ca2..461fa2b577 100644
--- a/configure.ac
+++ b/configure.ac
@@ -393,9 +393,9 @@ AC_CONFIG_COMMANDS([syscalls.h], [cd ${ac_top_srcdir}/include/lapi/syscalls; ./g
 # NOTE: don't create custom functions for simple checks, put them into this file
 LTP_CHECK_ACL_SUPPORT
 LTP_CHECK_ATOMIC_MEMORY_MODEL
-LTP_CHECK_BUILTIN_CLEAR_CACHE
 LTP_CHECK_CAPABILITY_SUPPORT
 LTP_CHECK_CC_WARN_OLDSTYLE
+LTP_CHECK_CLEAR_CACHE
 LTP_CHECK_CRYPTO
 LTP_CHECK_FORTIFY_SOURCE
 LTP_CHECK_KERNEL_DEVEL
diff --git a/m4/ltp-builtin_clear_cache.m4 b/m4/ltp-builtin_clear_cache.m4
deleted file mode 100644
index 86e1cfc914..0000000000
--- a/m4/ltp-builtin_clear_cache.m4
+++ /dev/null
@@ -1,19 +0,0 @@
-dnl SPDX-License-Identifier: GPL-2.0-or-later
-dnl Copyright (c) Linux Test Project, 2016
-
-AC_DEFUN([LTP_CHECK_BUILTIN_CLEAR_CACHE],[
-	AC_MSG_CHECKING([for __builtin___clear_cache])
-	AC_LINK_IFELSE([AC_LANG_SOURCE([[
-int main(void) {
-	char arr[16];
-	__builtin___clear_cache(arr, arr + sizeof(arr));
-        return 0;
-}]])],[has_bcc="yes"])
-
-if test "x$has_bcc" = xyes; then
-	AC_DEFINE(HAVE_BUILTIN_CLEAR_CACHE,1,[Define to 1 if you have __builtin___clear_cache])
-	AC_MSG_RESULT(yes)
-else
-	AC_MSG_RESULT(no)
-fi
-])
diff --git a/m4/ltp-clear_cache.m4 b/m4/ltp-clear_cache.m4
new file mode 100644
index 0000000000..99c6a1b653
--- /dev/null
+++ b/m4/ltp-clear_cache.m4
@@ -0,0 +1,20 @@
+dnl SPDX-License-Identifier: GPL-2.0-or-later
+dnl Copyright (c) Linux Test Project, 2016
+dnl Copyright (c) Linux Test Project, 2025
+
+AC_DEFUN([LTP_CHECK_CLEAR_CACHE],[
+	AC_MSG_CHECKING([for __clear_cache])
+	AC_LINK_IFELSE([AC_LANG_SOURCE([[
+int main(void) {
+	char arr[16];
+	__clear_cache(arr, arr + sizeof(arr));
+        return 0;
+}]])],[has_clear_cache="yes"])
+
+if test "x$has_clear_cache" = xyes; then
+	AC_DEFINE(HAVE_CLEAR_CACHE, 1, [Define to 1 if you have __clear_cache])
+	AC_MSG_RESULT(yes)
+else
+	AC_MSG_RESULT(no)
+fi
+])
diff --git a/testcases/kernel/syscalls/mprotect/mprotect04.c b/testcases/kernel/syscalls/mprotect/mprotect04.c
index 6c7f6bd017..fa4d3be4ba 100644
--- a/testcases/kernel/syscalls/mprotect/mprotect04.c
+++ b/testcases/kernel/syscalls/mprotect/mprotect04.c
@@ -152,11 +152,10 @@ static int page_present(void *p)
 
 static void clear_cache(void *start, int len)
 {
-#if HAVE_BUILTIN_CLEAR_CACHE == 1
-	__builtin___clear_cache(start, start + len);
+#ifdef HAVE_CLEAR_CACHE
+	__clear_cache(start, start + len);
 #else
-	tst_brkm(TCONF, cleanup,
-		"compiler doesn't have __builtin___clear_cache()");
+	tst_brkm(TCONF, cleanup, "compiler doesn't have __clear_cache()");
 #endif
 }
 
-- 
2.51.0


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Mailing list info: https://lists.linux.it/listinfo/ltp

[LTP] [PATCH 2/2] hugemmap15: Check for __clear_cache()

[Petr Vorel]

It fails to compile at least on riscv64 with older compiler.
It looks like it requires clang >= 20.1.0.

Reported-by: Khem Raj <raj.khem@gmail.com>
Cc: Hui Min Mina Chou <minachou@andestech.com>
Signed-off-by: Petr Vorel <petr.vorel@gmail.com>
---
 testcases/kernel/mem/hugetlb/hugemmap/hugemmap15.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/testcases/kernel/mem/hugetlb/hugemmap/hugemmap15.c b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap15.c
index 1dde9e87ba..641c021809 100644
--- a/testcases/kernel/mem/hugetlb/hugemmap/hugemmap15.c
+++ b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap15.c
@@ -46,7 +46,10 @@ static void cacheflush(void *p)
 #if defined(__powerpc__)
 	asm volatile("dcbst 0,%0; sync; icbi 0,%0; isync" : : "r"(p));
 #elif defined(__arm__) || defined(__aarch64__) || defined(__riscv) || defined(__loongarch__)
+# ifdef HAVE_CLEAR_CACHE
 	__clear_cache(p, p + COPY_SIZE);
+# else
+	tst_brk(TCONF, "compiler doesn't have __clear_cache()");
 #else
 	(void)p;
 #endif
-- 
2.51.0


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Mailing list info: https://lists.linux.it/listinfo/ltp

Re: [LTP] [PATCH 1/2] m4: mprotect04: Replace __builtin___clear_cache with __clear_cache

[Andrea Cervesato via ltp]

Hi!

On Sun Oct 12, 2025 at 9:40 PM CEST, Petr Vorel wrote:
> __clear_cache() should be quite common now and we already use it in
> hugemmap15.c. Convert autotools m4 check to detect it.
>
> Signed-off-by: Petr Vorel <petr.vorel@gmail.com>
> ---
>  configure.ac                                  |  2 +-
>  m4/ltp-builtin_clear_cache.m4                 | 19 ------------------
>  m4/ltp-clear_cache.m4                         | 20 +++++++++++++++++++
>  .../kernel/syscalls/mprotect/mprotect04.c     |  7 +++----
>  4 files changed, 24 insertions(+), 24 deletions(-)
>  delete mode 100644 m4/ltp-builtin_clear_cache.m4
>  create mode 100644 m4/ltp-clear_cache.m4
>
> diff --git a/configure.ac b/configure.ac
> index 0480f46ca2..461fa2b577 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -393,9 +393,9 @@ AC_CONFIG_COMMANDS([syscalls.h], [cd ${ac_top_srcdir}/include/lapi/syscalls; ./g
>  # NOTE: don't create custom functions for simple checks, put them into this file
>  LTP_CHECK_ACL_SUPPORT
>  LTP_CHECK_ATOMIC_MEMORY_MODEL
> -LTP_CHECK_BUILTIN_CLEAR_CACHE
>  LTP_CHECK_CAPABILITY_SUPPORT
>  LTP_CHECK_CC_WARN_OLDSTYLE
> +LTP_CHECK_CLEAR_CACHE
>  LTP_CHECK_CRYPTO
>  LTP_CHECK_FORTIFY_SOURCE
>  LTP_CHECK_KERNEL_DEVEL
> diff --git a/m4/ltp-builtin_clear_cache.m4 b/m4/ltp-builtin_clear_cache.m4
> deleted file mode 100644
> index 86e1cfc914..0000000000
> --- a/m4/ltp-builtin_clear_cache.m4
> +++ /dev/null
> @@ -1,19 +0,0 @@
> -dnl SPDX-License-Identifier: GPL-2.0-or-later
> -dnl Copyright (c) Linux Test Project, 2016
> -
> -AC_DEFUN([LTP_CHECK_BUILTIN_CLEAR_CACHE],[
> -	AC_MSG_CHECKING([for __builtin___clear_cache])
> -	AC_LINK_IFELSE([AC_LANG_SOURCE([[
> -int main(void) {
> -	char arr[16];
> -	__builtin___clear_cache(arr, arr + sizeof(arr));
> -        return 0;
> -}]])],[has_bcc="yes"])
> -
> -if test "x$has_bcc" = xyes; then
> -	AC_DEFINE(HAVE_BUILTIN_CLEAR_CACHE,1,[Define to 1 if you have __builtin___clear_cache])
> -	AC_MSG_RESULT(yes)
> -else
> -	AC_MSG_RESULT(no)
> -fi
> -])
> diff --git a/m4/ltp-clear_cache.m4 b/m4/ltp-clear_cache.m4
> new file mode 100644
> index 0000000000..99c6a1b653
> --- /dev/null
> +++ b/m4/ltp-clear_cache.m4
> @@ -0,0 +1,20 @@
> +dnl SPDX-License-Identifier: GPL-2.0-or-later
> +dnl Copyright (c) Linux Test Project, 2016
> +dnl Copyright (c) Linux Test Project, 2025
> +
> +AC_DEFUN([LTP_CHECK_CLEAR_CACHE],[
> +	AC_MSG_CHECKING([for __clear_cache])
> +	AC_LINK_IFELSE([AC_LANG_SOURCE([[
> +int main(void) {
> +	char arr[16];
> +	__clear_cache(arr, arr + sizeof(arr));
> +        return 0;
> +}]])],[has_clear_cache="yes"])
> +
> +if test "x$has_clear_cache" = xyes; then
> +	AC_DEFINE(HAVE_CLEAR_CACHE, 1, [Define to 1 if you have __clear_cache])
> +	AC_MSG_RESULT(yes)
> +else
> +	AC_MSG_RESULT(no)
> +fi
> +])
> diff --git a/testcases/kernel/syscalls/mprotect/mprotect04.c b/testcases/kernel/syscalls/mprotect/mprotect04.c
> index 6c7f6bd017..fa4d3be4ba 100644
> --- a/testcases/kernel/syscalls/mprotect/mprotect04.c
> +++ b/testcases/kernel/syscalls/mprotect/mprotect04.c
> @@ -152,11 +152,10 @@ static int page_present(void *p)
>  
>  static void clear_cache(void *start, int len)
>  {
> -#if HAVE_BUILTIN_CLEAR_CACHE == 1
> -	__builtin___clear_cache(start, start + len);
> +#ifdef HAVE_CLEAR_CACHE

I'm not 100% sure if it's a good idea to rename HAVE_BUILTIN_CLEAR_CACHE
to HAVE_CLEAR_CACHE, since this syntax is often used inside tests to
check if we have missing syscalls/functions inside libc implementation.

I would keep HAVE_BUILTIN_CLEAR_CACHE anyway in this case, since it's a
strictly compiler related feature.

> +	__clear_cache(start, start + len);
>  #else
> -	tst_brkm(TCONF, cleanup,
> -		"compiler doesn't have __builtin___clear_cache()");
> +	tst_brkm(TCONF, cleanup, "compiler doesn't have __clear_cache()");
>  #endif
>  }
>  

-- 
Andrea Cervesato
SUSE QE Automation Engineer Linux
andrea.cervesato@suse.com


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