Patch "selftests: sigaltstack: fix -Wuninitialized" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    selftests: sigaltstack: fix -Wuninitialized

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     selftests-sigaltstack-fix-wuninitialized.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 526982fa01c80fc47a592e373b71e5f6e78aaa1b
Author: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Date:   Wed Mar 8 11:59:33 2023 -0800

    selftests: sigaltstack: fix -Wuninitialized
    
    [ Upstream commit 05107edc910135d27fe557267dc45be9630bf3dd ]
    
    Building sigaltstack with clang via:
    $ ARCH=x86 make LLVM=1 -C tools/testing/selftests/sigaltstack/
    
    produces the following warning:
      warning: variable 'sp' is uninitialized when used here [-Wuninitialized]
      if (sp < (unsigned long)sstack ||
          ^~
    
    Clang expects these to be declared at global scope; we've fixed this in
    the kernel proper by using the macro `current_stack_pointer`. This is
    defined in different headers for different target architectures, so just
    create a new header that defines the arch-specific register names for
    the stack pointer register, and define it for more targets (at least the
    ones that support current_stack_pointer/ARCH_HAS_CURRENT_STACK_POINTER).
    
    Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>
    Link: https://lore.kernel.org/lkml/CA+G9fYsi3OOu7yCsMutpzKDnBMAzJBCPimBp86LhGBa0eCnEpA@xxxxxxxxxxxxxx/
    Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
    Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
    Tested-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>
    Tested-by: Anders Roxell <anders.roxell@xxxxxxxxxx>
    Signed-off-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/tools/testing/selftests/sigaltstack/current_stack_pointer.h b/tools/testing/selftests/sigaltstack/current_stack_pointer.h
new file mode 100644
index 0000000000000..ea9bdf3a90b16
--- /dev/null
+++ b/tools/testing/selftests/sigaltstack/current_stack_pointer.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#if __alpha__
+register unsigned long sp asm("$30");
+#elif __arm__ || __aarch64__ || __csky__ || __m68k__ || __mips__ || __riscv
+register unsigned long sp asm("sp");
+#elif __i386__
+register unsigned long sp asm("esp");
+#elif __loongarch64
+register unsigned long sp asm("$sp");
+#elif __ppc__
+register unsigned long sp asm("r1");
+#elif __s390x__
+register unsigned long sp asm("%15");
+#elif __sh__
+register unsigned long sp asm("r15");
+#elif __x86_64__
+register unsigned long sp asm("rsp");
+#elif __XTENSA__
+register unsigned long sp asm("a1");
+#else
+#error "implement current_stack_pointer equivalent"
+#endif
diff --git a/tools/testing/selftests/sigaltstack/sas.c b/tools/testing/selftests/sigaltstack/sas.c
index c53b070755b65..98d37cb744fb2 100644
--- a/tools/testing/selftests/sigaltstack/sas.c
+++ b/tools/testing/selftests/sigaltstack/sas.c
@@ -20,6 +20,7 @@
 #include <sys/auxv.h>
 
 #include "../kselftest.h"
+#include "current_stack_pointer.h"
 
 #ifndef SS_AUTODISARM
 #define SS_AUTODISARM  (1U << 31)
@@ -46,12 +47,6 @@ void my_usr1(int sig, siginfo_t *si, void *u)
 	stack_t stk;
 	struct stk_data *p;
 
-#if __s390x__
-	register unsigned long sp asm("%15");
-#else
-	register unsigned long sp asm("sp");
-#endif
-
 	if (sp < (unsigned long)sstack ||
 			sp >= (unsigned long)sstack + stack_size) {
 		ksft_exit_fail_msg("SP is not on sigaltstack\n");