* [PATCH] mips: Implement "current_stack_pointer"
@ 2022-02-24 6:04 Kees Cook
2022-03-01 16:30 ` Thomas Bogendoerfer
0 siblings, 1 reply; 2+ messages in thread
From: Kees Cook @ 2022-02-24 6:04 UTC (permalink / raw)
To: Thomas Bogendoerfer
Cc: Kees Cook, Marc Zyngier, Guenter Roeck, Mark Rutland, Yanteng Si,
linux-mips, linux-kernel, linux-hardening
To follow the existing per-arch conventions replace open-coded uses
of asm "sp" as "current_stack_pointer". This will let it be used in
non-arch places (like HARDENED_USERCOPY).
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Yanteng Si <siyanteng01@gmail.com>
Cc: linux-mips@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
arch/mips/Kconfig | 1 +
arch/mips/include/asm/thread_info.h | 2 ++
arch/mips/kernel/irq.c | 3 +--
arch/mips/lib/uncached.c | 4 +---
4 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 058446f01487..6781f87e2218 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -4,6 +4,7 @@ config MIPS
default y
select ARCH_32BIT_OFF_T if !64BIT
select ARCH_BINFMT_ELF_STATE if MIPS_FP_SUPPORT
+ select ARCH_HAS_CURRENT_STACK_POINTER
select ARCH_HAS_DEBUG_VIRTUAL if !64BIT
select ARCH_HAS_FORTIFY_SOURCE
select ARCH_HAS_KCOV
diff --git a/arch/mips/include/asm/thread_info.h b/arch/mips/include/asm/thread_info.h
index 0b17aaa9e012..4463348d2372 100644
--- a/arch/mips/include/asm/thread_info.h
+++ b/arch/mips/include/asm/thread_info.h
@@ -69,6 +69,8 @@ static inline struct thread_info *current_thread_info(void)
return __current_thread_info;
}
+register unsigned long current_stack_pointer __asm__("sp");
+
#endif /* !__ASSEMBLY__ */
/* thread information allocation */
diff --git a/arch/mips/kernel/irq.c b/arch/mips/kernel/irq.c
index 5e11582fe308..fc313c49a417 100644
--- a/arch/mips/kernel/irq.c
+++ b/arch/mips/kernel/irq.c
@@ -75,9 +75,8 @@ void __init init_IRQ(void)
#ifdef CONFIG_DEBUG_STACKOVERFLOW
static inline void check_stack_overflow(void)
{
- unsigned long sp;
+ unsigned long sp = current_stack_pointer;
- __asm__ __volatile__("move %0, $sp" : "=r" (sp));
sp &= THREAD_MASK;
/*
diff --git a/arch/mips/lib/uncached.c b/arch/mips/lib/uncached.c
index f80a67c092b6..f8d4ca046c3e 100644
--- a/arch/mips/lib/uncached.c
+++ b/arch/mips/lib/uncached.c
@@ -40,9 +40,7 @@ unsigned long run_uncached(void *func)
register long ret __asm__("$2");
long lfunc = (long)func, ufunc;
long usp;
- long sp;
-
- __asm__("move %0, $sp" : "=r" (sp));
+ long sp = current_stack_pointer;
if (sp >= (long)CKSEG0 && sp < (long)CKSEG2)
usp = CKSEG1ADDR(sp);
--
2.30.2
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] mips: Implement "current_stack_pointer"
2022-02-24 6:04 [PATCH] mips: Implement "current_stack_pointer" Kees Cook
@ 2022-03-01 16:30 ` Thomas Bogendoerfer
0 siblings, 0 replies; 2+ messages in thread
From: Thomas Bogendoerfer @ 2022-03-01 16:30 UTC (permalink / raw)
To: Kees Cook
Cc: Marc Zyngier, Guenter Roeck, Mark Rutland, Yanteng Si,
linux-mips, linux-kernel, linux-hardening
On Wed, Feb 23, 2022 at 10:04:32PM -0800, Kees Cook wrote:
> To follow the existing per-arch conventions replace open-coded uses
> of asm "sp" as "current_stack_pointer". This will let it be used in
> non-arch places (like HARDENED_USERCOPY).
>
> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: Guenter Roeck <linux@roeck-us.net>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Yanteng Si <siyanteng01@gmail.com>
> Cc: linux-mips@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> arch/mips/Kconfig | 1 +
> arch/mips/include/asm/thread_info.h | 2 ++
> arch/mips/kernel/irq.c | 3 +--
> arch/mips/lib/uncached.c | 4 +---
> 4 files changed, 5 insertions(+), 5 deletions(-)
applied to mips-next.
Thomas.
--
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea. [ RFC1925, 2.3 ]
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