From: Nick Desaulniers ndesaulniers@google.com

[ 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@linaro.org Link: https://lore.kernel.org/lkml/CA+G9fYsi3OOu7yCsMutpzKDnBMAzJBCPimBp86LhGBa0eC... Signed-off-by: Nick Desaulniers ndesaulniers@google.com Reviewed-by: Kees Cook keescook@chromium.org Tested-by: Linux Kernel Functional Testing lkft@linaro.org Tested-by: Anders Roxell anders.roxell@linaro.org Signed-off-by: Shuah Khan skhan@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- .../sigaltstack/current_stack_pointer.h | 23 +++++++++++++++++++ tools/testing/selftests/sigaltstack/sas.c | 7 +----- 2 files changed, 24 insertions(+), 6 deletions(-) create mode 100644 tools/testing/selftests/sigaltstack/current_stack_pointer.h

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 ad0f8df2ca0af..6e60545994916 100644 --- a/tools/testing/selftests/sigaltstack/sas.c +++ b/tools/testing/selftests/sigaltstack/sas.c @@ -19,6 +19,7 @@ #include <errno.h>

#include "../kselftest.h" +#include "current_stack_pointer.h"

#ifndef SS_AUTODISARM #define SS_AUTODISARM (1U << 31) @@ -40,12 +41,6 @@ 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 + SIGSTKSZ) { ksft_exit_fail_msg("SP is not on sigaltstack\n");