[PATCH] alpha: Implement "current_stack_pointer"

[PATCH] alpha: Implement "current_stack_pointer"

[Kees Cook]

To follow the existing per-arch conventions replace open-coded use
of asm "$30" as "current_stack_pointer". This will let it be used in
non-arch places (like HARDENED_USERCOPY).

Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: "Alexander A. Klimov" <grandmaster@al2klimov.de>
Cc: linux-alpha@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 arch/alpha/Kconfig                   | 1 +
 arch/alpha/include/asm/thread_info.h | 2 ++
 arch/alpha/lib/stacktrace.c          | 2 +-
 3 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 4e87783c90ad..31f3dbcdc28c 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -3,6 +3,7 @@ config ALPHA
 	bool
 	default y
 	select ARCH_32BIT_USTAT_F_TINODE
+	select ARCH_HAS_CURRENT_STACK_POINTER
 	select ARCH_MIGHT_HAVE_PC_PARPORT
 	select ARCH_MIGHT_HAVE_PC_SERIO
 	select ARCH_NO_PREEMPT
diff --git a/arch/alpha/include/asm/thread_info.h b/arch/alpha/include/asm/thread_info.h
index 2592356e3215..28214db31053 100644
--- a/arch/alpha/include/asm/thread_info.h
+++ b/arch/alpha/include/asm/thread_info.h
@@ -43,6 +43,8 @@ struct thread_info {
 register struct thread_info *__current_thread_info __asm__("$8");
 #define current_thread_info()  __current_thread_info
 
+register unsigned long *current_stack_pointer __asm__ ("$30");
+
 #endif /* __ASSEMBLY__ */
 
 /* Thread information allocation.  */
diff --git a/arch/alpha/lib/stacktrace.c b/arch/alpha/lib/stacktrace.c
index 62454a7810e2..2b1176dd5174 100644
--- a/arch/alpha/lib/stacktrace.c
+++ b/arch/alpha/lib/stacktrace.c
@@ -92,7 +92,7 @@ stacktrace(void)
 {
 	instr * ret_pc;
 	instr * prologue = (instr *)stacktrace;
-	register unsigned char * sp __asm__ ("$30");
+	unsigned char *sp = (unsigned char *)current_stack_pointer;
 
 	printk("\tstack trace:\n");
 	do {
-- 
2.30.2

Re: [PATCH] alpha: Implement "current_stack_pointer"

[Matt Turner]

On Thu, Feb 24, 2022 at 1:06 AM Kees Cook <keescook@chromium.org> wrote:
>
> To follow the existing per-arch conventions replace open-coded use
> of asm "$30" as "current_stack_pointer". This will let it be used in
> non-arch places (like HARDENED_USERCOPY).
>
> Cc: Richard Henderson <rth@twiddle.net>
> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
> Cc: Matt Turner <mattst88@gmail.com>
> Cc: Geert Uytterhoeven <geert@linux-m68k.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Mike Rapoport <rppt@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
> Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
> Cc: "Alexander A. Klimov" <grandmaster@al2klimov.de>
> Cc: linux-alpha@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  arch/alpha/Kconfig                   | 1 +
>  arch/alpha/include/asm/thread_info.h | 2 ++
>  arch/alpha/lib/stacktrace.c          | 2 +-
>  3 files changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
> index 4e87783c90ad..31f3dbcdc28c 100644
> --- a/arch/alpha/Kconfig
> +++ b/arch/alpha/Kconfig
> @@ -3,6 +3,7 @@ config ALPHA
>         bool
>         default y
>         select ARCH_32BIT_USTAT_F_TINODE
> +       select ARCH_HAS_CURRENT_STACK_POINTER
>         select ARCH_MIGHT_HAVE_PC_PARPORT
>         select ARCH_MIGHT_HAVE_PC_SERIO
>         select ARCH_NO_PREEMPT
> diff --git a/arch/alpha/include/asm/thread_info.h b/arch/alpha/include/asm/thread_info.h
> index 2592356e3215..28214db31053 100644
> --- a/arch/alpha/include/asm/thread_info.h
> +++ b/arch/alpha/include/asm/thread_info.h
> @@ -43,6 +43,8 @@ struct thread_info {
>  register struct thread_info *__current_thread_info __asm__("$8");
>  #define current_thread_info()  __current_thread_info
>
> +register unsigned long *current_stack_pointer __asm__ ("$30");
> +
>  #endif /* __ASSEMBLY__ */
>
>  /* Thread information allocation.  */
> diff --git a/arch/alpha/lib/stacktrace.c b/arch/alpha/lib/stacktrace.c
> index 62454a7810e2..2b1176dd5174 100644
> --- a/arch/alpha/lib/stacktrace.c
> +++ b/arch/alpha/lib/stacktrace.c
> @@ -92,7 +92,7 @@ stacktrace(void)
>  {
>         instr * ret_pc;
>         instr * prologue = (instr *)stacktrace;
> -       register unsigned char * sp __asm__ ("$30");
> +       unsigned char *sp = (unsigned char *)current_stack_pointer;
>
>         printk("\tstack trace:\n");
>         do {
> --
> 2.30.2
>

Thanks for the patch! This was included in my pull request today and
is now upstream in Linus' tree.

Re: [PATCH] alpha: Implement "current_stack_pointer"

[Arnd Bergmann]

On Sun, Feb 26, 2023, at 03:08, Matt Turner wrote:
>
> Thanks for the patch! This was included in my pull request today and
> is now upstream in Linus' tree.

[trimming Cc list for hijacked thread]

Hi Matt,

I remember that Stephen Rothwell mentioned he dropped a couple of
architecture trees from linux-next due to long inactivity, and I
see that none of your branches are included any more. Should

https://git.kernel.org/pub/scm/linux/kernel/git/mattst88/alpha.git/log/?h=for-linus

or the (currently empty) alpha-next branch be added back there?

      Arnd

Re: [PATCH] alpha: Implement "current_stack_pointer"

[Stephen Rothwell]

[-- Attachment #1: Type: text/plain, Size: 814 bytes --]

Hi Arnd,

On Sun, 26 Feb 2023 11:24:13 +0100 "Arnd Bergmann" <arnd@arndb.de> wrote:
>
> On Sun, Feb 26, 2023, at 03:08, Matt Turner wrote:
> >
> > Thanks for the patch! This was included in my pull request today and
> > is now upstream in Linus' tree.  
> 
> [trimming Cc list for hijacked thread]
> 
> Hi Matt,
> 
> I remember that Stephen Rothwell mentioned he dropped a couple of
> architecture trees from linux-next due to long inactivity, and I
> see that none of your branches are included any more. Should
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/mattst88/alpha.git/log/?h=for-linus
> 
> or the (currently empty) alpha-next branch be added back there?

There has never been an alpha branch in linux-next.

I would welcome one, however ;-)
-- 
Cheers,
Stephen Rothwell

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 488 bytes --]