mips: Implement "current_stack_pointer"

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>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 59dabfd..451ee7a 100644 (file)
--- 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 0b17aaa..4463348 100644 (file)
--- 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 5e11582..fc313c4 100644 (file)
--- 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 f80a67c..f8d4ca0 100644 (file)
--- 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);