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-rw-r--r--arch/x86/Kconfig2
-rw-r--r--arch/x86/include/asm/refcount.h2
-rw-r--r--arch/x86/include/asm/rwsem.h53
-rw-r--r--arch/x86/mm/extable.c7
4 files changed, 35 insertions, 29 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 971feac13506..90535646b83d 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -55,7 +55,7 @@ config X86
select ARCH_HAS_KCOV if X86_64
select ARCH_HAS_PMEM_API if X86_64
# Causing hangs/crashes, see the commit that added this change for details.
- select ARCH_HAS_REFCOUNT if BROKEN
+ select ARCH_HAS_REFCOUNT
select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
select ARCH_HAS_SET_MEMORY
select ARCH_HAS_SG_CHAIN
diff --git a/arch/x86/include/asm/refcount.h b/arch/x86/include/asm/refcount.h
index ff871210b9f2..4e44250e7d0d 100644
--- a/arch/x86/include/asm/refcount.h
+++ b/arch/x86/include/asm/refcount.h
@@ -15,7 +15,7 @@
* back to the regular execution flow in .text.
*/
#define _REFCOUNT_EXCEPTION \
- ".pushsection .text.unlikely\n" \
+ ".pushsection .text..refcount\n" \
"111:\tlea %[counter], %%" _ASM_CX "\n" \
"112:\t" ASM_UD0 "\n" \
ASM_UNREACHABLE \
diff --git a/arch/x86/include/asm/rwsem.h b/arch/x86/include/asm/rwsem.h
index 7116b7931c7b..a8f486e7a124 100644
--- a/arch/x86/include/asm/rwsem.h
+++ b/arch/x86/include/asm/rwsem.h
@@ -63,14 +63,14 @@
static inline void __down_read(struct rw_semaphore *sem)
{
asm volatile("# beginning down_read\n\t"
- LOCK_PREFIX _ASM_INC "(%1)\n\t"
+ LOCK_PREFIX _ASM_INC "(%[sem])\n\t"
/* adds 0x00000001 */
" jns 1f\n"
" call call_rwsem_down_read_failed\n"
"1:\n\t"
"# ending down_read\n\t"
: "+m" (sem->count)
- : "a" (sem)
+ : [sem] "a" (sem)
: "memory", "cc");
}
@@ -81,17 +81,18 @@ static inline bool __down_read_trylock(struct rw_semaphore *sem)
{
long result, tmp;
asm volatile("# beginning __down_read_trylock\n\t"
- " mov %0,%1\n\t"
+ " mov %[count],%[result]\n\t"
"1:\n\t"
- " mov %1,%2\n\t"
- " add %3,%2\n\t"
+ " mov %[result],%[tmp]\n\t"
+ " add %[inc],%[tmp]\n\t"
" jle 2f\n\t"
- LOCK_PREFIX " cmpxchg %2,%0\n\t"
+ LOCK_PREFIX " cmpxchg %[tmp],%[count]\n\t"
" jnz 1b\n\t"
"2:\n\t"
"# ending __down_read_trylock\n\t"
- : "+m" (sem->count), "=&a" (result), "=&r" (tmp)
- : "i" (RWSEM_ACTIVE_READ_BIAS)
+ : [count] "+m" (sem->count), [result] "=&a" (result),
+ [tmp] "=&r" (tmp)
+ : [inc] "i" (RWSEM_ACTIVE_READ_BIAS)
: "memory", "cc");
return result >= 0;
}
@@ -105,7 +106,7 @@ static inline bool __down_read_trylock(struct rw_semaphore *sem)
struct rw_semaphore* ret; \
\
asm volatile("# beginning down_write\n\t" \
- LOCK_PREFIX " xadd %1,(%4)\n\t" \
+ LOCK_PREFIX " xadd %[tmp],(%[sem])\n\t" \
/* adds 0xffff0001, returns the old value */ \
" test " __ASM_SEL(%w1,%k1) "," __ASM_SEL(%w1,%k1) "\n\t" \
/* was the active mask 0 before? */\
@@ -113,9 +114,9 @@ static inline bool __down_read_trylock(struct rw_semaphore *sem)
" call " slow_path "\n" \
"1:\n" \
"# ending down_write" \
- : "+m" (sem->count), "=d" (tmp), \
+ : "+m" (sem->count), [tmp] "=d" (tmp), \
"=a" (ret), ASM_CALL_CONSTRAINT \
- : "a" (sem), "1" (RWSEM_ACTIVE_WRITE_BIAS) \
+ : [sem] "a" (sem), "[tmp]" (RWSEM_ACTIVE_WRITE_BIAS) \
: "memory", "cc"); \
ret; \
})
@@ -141,21 +142,21 @@ static inline bool __down_write_trylock(struct rw_semaphore *sem)
bool result;
long tmp0, tmp1;
asm volatile("# beginning __down_write_trylock\n\t"
- " mov %0,%1\n\t"
+ " mov %[count],%[tmp0]\n\t"
"1:\n\t"
" test " __ASM_SEL(%w1,%k1) "," __ASM_SEL(%w1,%k1) "\n\t"
/* was the active mask 0 before? */
" jnz 2f\n\t"
- " mov %1,%2\n\t"
- " add %4,%2\n\t"
- LOCK_PREFIX " cmpxchg %2,%0\n\t"
+ " mov %[tmp0],%[tmp1]\n\t"
+ " add %[inc],%[tmp1]\n\t"
+ LOCK_PREFIX " cmpxchg %[tmp1],%[count]\n\t"
" jnz 1b\n\t"
"2:\n\t"
CC_SET(e)
"# ending __down_write_trylock\n\t"
- : "+m" (sem->count), "=&a" (tmp0), "=&r" (tmp1),
- CC_OUT(e) (result)
- : "er" (RWSEM_ACTIVE_WRITE_BIAS)
+ : [count] "+m" (sem->count), [tmp0] "=&a" (tmp0),
+ [tmp1] "=&r" (tmp1), CC_OUT(e) (result)
+ : [inc] "er" (RWSEM_ACTIVE_WRITE_BIAS)
: "memory");
return result;
}
@@ -167,14 +168,14 @@ static inline void __up_read(struct rw_semaphore *sem)
{
long tmp;
asm volatile("# beginning __up_read\n\t"
- LOCK_PREFIX " xadd %1,(%2)\n\t"
+ LOCK_PREFIX " xadd %[tmp],(%[sem])\n\t"
/* subtracts 1, returns the old value */
" jns 1f\n\t"
" call call_rwsem_wake\n" /* expects old value in %edx */
"1:\n"
"# ending __up_read\n"
- : "+m" (sem->count), "=d" (tmp)
- : "a" (sem), "1" (-RWSEM_ACTIVE_READ_BIAS)
+ : "+m" (sem->count), [tmp] "=d" (tmp)
+ : [sem] "a" (sem), "[tmp]" (-RWSEM_ACTIVE_READ_BIAS)
: "memory", "cc");
}
@@ -185,14 +186,14 @@ static inline void __up_write(struct rw_semaphore *sem)
{
long tmp;
asm volatile("# beginning __up_write\n\t"
- LOCK_PREFIX " xadd %1,(%2)\n\t"
+ LOCK_PREFIX " xadd %[tmp],(%[sem])\n\t"
/* subtracts 0xffff0001, returns the old value */
" jns 1f\n\t"
" call call_rwsem_wake\n" /* expects old value in %edx */
"1:\n\t"
"# ending __up_write\n"
- : "+m" (sem->count), "=d" (tmp)
- : "a" (sem), "1" (-RWSEM_ACTIVE_WRITE_BIAS)
+ : "+m" (sem->count), [tmp] "=d" (tmp)
+ : [sem] "a" (sem), "[tmp]" (-RWSEM_ACTIVE_WRITE_BIAS)
: "memory", "cc");
}
@@ -202,7 +203,7 @@ static inline void __up_write(struct rw_semaphore *sem)
static inline void __downgrade_write(struct rw_semaphore *sem)
{
asm volatile("# beginning __downgrade_write\n\t"
- LOCK_PREFIX _ASM_ADD "%2,(%1)\n\t"
+ LOCK_PREFIX _ASM_ADD "%[inc],(%[sem])\n\t"
/*
* transitions 0xZZZZ0001 -> 0xYYYY0001 (i386)
* 0xZZZZZZZZ00000001 -> 0xYYYYYYYY00000001 (x86_64)
@@ -212,7 +213,7 @@ static inline void __downgrade_write(struct rw_semaphore *sem)
"1:\n\t"
"# ending __downgrade_write\n"
: "+m" (sem->count)
- : "a" (sem), "er" (-RWSEM_WAITING_BIAS)
+ : [sem] "a" (sem), [inc] "er" (-RWSEM_WAITING_BIAS)
: "memory", "cc");
}
diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c
index c3521e2be396..3321b446b66c 100644
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -67,12 +67,17 @@ bool ex_handler_refcount(const struct exception_table_entry *fixup,
* wrapped around) will be set. Additionally, seeing the refcount
* reach 0 will set ZF (Zero Flag: result was zero). In each of
* these cases we want a report, since it's a boundary condition.
- *
+ * The SF case is not reported since it indicates post-boundary
+ * manipulations below zero or above INT_MAX. And if none of the
+ * flags are set, something has gone very wrong, so report it.
*/
if (regs->flags & (X86_EFLAGS_OF | X86_EFLAGS_ZF)) {
bool zero = regs->flags & X86_EFLAGS_ZF;
refcount_error_report(regs, zero ? "hit zero" : "overflow");
+ } else if ((regs->flags & X86_EFLAGS_SF) == 0) {
+ /* Report if none of OF, ZF, nor SF are set. */
+ refcount_error_report(regs, "unexpected saturation");
}
return true;
generated by cgit (git 2.34.1) at 2024-05-20 14:15:20 +0000