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Subject[PATCH] xtensa: Implement "current_stack_pointer"
Date
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: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: linux-xtensa@linux-xtensa.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
arch/xtensa/Kconfig | 1 +
arch/xtensa/include/asm/current.h | 2 ++
arch/xtensa/include/asm/stacktrace.h | 2 +-
arch/xtensa/kernel/irq.c | 3 +--
4 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index 8ac599aa6d99..887432327613 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -3,6 +3,7 @@ config XTENSA
def_bool y
select ARCH_32BIT_OFF_T
select ARCH_HAS_BINFMT_FLAT if !MMU
+ select ARCH_HAS_CURRENT_STACK_POINTER
select ARCH_HAS_DMA_PREP_COHERENT if MMU
select ARCH_HAS_SYNC_DMA_FOR_CPU if MMU
select ARCH_HAS_SYNC_DMA_FOR_DEVICE if MMU
diff --git a/arch/xtensa/include/asm/current.h b/arch/xtensa/include/asm/current.h
index 5d98a7ad4251..08010dbf5e09 100644
--- a/arch/xtensa/include/asm/current.h
+++ b/arch/xtensa/include/asm/current.h
@@ -26,6 +26,8 @@ static inline struct task_struct *get_current(void)

#define current get_current()

+register unsigned long current_stack_pointer __asm__("a1");
+
#else

#define GET_CURRENT(reg,sp) \
diff --git a/arch/xtensa/include/asm/stacktrace.h b/arch/xtensa/include/asm/stacktrace.h
index fe06e8ed162b..4d84fd6bd43c 100644
--- a/arch/xtensa/include/asm/stacktrace.h
+++ b/arch/xtensa/include/asm/stacktrace.h
@@ -22,7 +22,7 @@ static __always_inline unsigned long *stack_pointer(struct task_struct *task)
unsigned long *sp;

if (!task || task == current)
- __asm__ __volatile__ ("mov %0, a1\n" : "=a"(sp));
+ sp = current_stack_pointer;
else
sp = (unsigned long *)task->thread.sp;

diff --git a/arch/xtensa/kernel/irq.c b/arch/xtensa/kernel/irq.c
index 15051a8a1539..529fe9245821 100644
--- a/arch/xtensa/kernel/irq.c
+++ b/arch/xtensa/kernel/irq.c
@@ -36,9 +36,8 @@ asmlinkage void do_IRQ(int hwirq, struct pt_regs *regs)
#ifdef CONFIG_DEBUG_STACKOVERFLOW
/* Debugging check for stack overflow: is there less than 1KB free? */
{
- unsigned long sp;
+ unsigned long sp = current_stack_pointer;

- __asm__ __volatile__ ("mov %0, a1\n" : "=a" (sp));
sp &= THREAD_SIZE - 1;

if (unlikely(sp < (sizeof(thread_info) + 1024)))
--
2.30.2
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