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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen stable-4.9] xen/arm64: cmpxchg: Simplify the cmpxchg implementation
commit f6b0f33b9cb06c3d0535720f7d940cf841797dc0
Author: Julien Grall <julien.grall@xxxxxxx>
AuthorDate: Wed May 22 13:37:53 2019 -0700
Commit: Julien Grall <julien.grall@xxxxxxx>
CommitDate: Fri Jun 14 14:49:19 2019 +0100
xen/arm64: cmpxchg: Simplify the cmpxchg implementation
The only difference between each case of the cmpxchg is the size of
used. Rather than duplicating the code, provide a macro to generate each
cases.
This makes the code easier to read and modify.
This is part of XSA-295.
Signed-off-by; Julien Grall <julien.grall@xxxxxxx>
Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>
---
xen/include/asm-arm/arm64/cmpxchg.h | 98 ++++++++++++++-----------------------
1 file changed, 36 insertions(+), 62 deletions(-)
diff --git a/xen/include/asm-arm/arm64/cmpxchg.h
b/xen/include/asm-arm/arm64/cmpxchg.h
index ae42b2f5ff..393fbca6a5 100644
--- a/xen/include/asm-arm/arm64/cmpxchg.h
+++ b/xen/include/asm-arm/arm64/cmpxchg.h
@@ -61,80 +61,54 @@ static inline unsigned long __xchg(unsigned long x,
volatile void *ptr, int size
__ret; \
})
-extern void __bad_cmpxchg(volatile void *ptr, int size);
+extern unsigned long __bad_cmpxchg(volatile void *ptr, int size);
+
+#define __CMPXCHG_CASE(w, sz, name) \
+static inline unsigned long __cmpxchg_case_##name(volatile void *ptr, \
+ unsigned long old, \
+ unsigned long new) \
+{ \
+ unsigned long res, oldval; \
+ \
+ do { \
+ asm volatile("// __cmpxchg_case_" #name "\n" \
+ " ldxr" #sz " %" #w "1, %2\n" \
+ " mov %w0, #0\n" \
+ " cmp %" #w "1, %" #w "3\n" \
+ " b.ne 1f\n" \
+ " stxr" #sz " %w0, %" #w "4, %2\n" \
+ "1:\n" \
+ : "=&r" (res), "=&r" (oldval), \
+ "+Q" (*(unsigned long *)ptr) \
+ : "Ir" (old), "r" (new) \
+ : "cc"); \
+ } while (res); \
+ \
+ return oldval; \
+}
+
+__CMPXCHG_CASE(w, b, 1)
+__CMPXCHG_CASE(w, h, 2)
+__CMPXCHG_CASE(w, , 4)
+__CMPXCHG_CASE( , , 8)
static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
unsigned long new, int size)
{
- unsigned long oldval = 0, res;
-
switch (size) {
case 1:
- do {
- asm volatile("// __cmpxchg1\n"
- " ldxrb %w1, %2\n"
- " mov %w0, #0\n"
- " cmp %w1, %w3\n"
- " b.ne 1f\n"
- " stxrb %w0, %w4, %2\n"
- "1:\n"
- : "=&r" (res), "=&r" (oldval), "+Q" (*(u8 *)ptr)
- : "Ir" (old), "r" (new)
- : "cc");
- } while (res);
- break;
-
+ return __cmpxchg_case_1(ptr, old, new);
case 2:
- do {
- asm volatile("// __cmpxchg2\n"
- " ldxrh %w1, %2\n"
- " mov %w0, #0\n"
- " cmp %w1, %w3\n"
- " b.ne 1f\n"
- " stxrh %w0, %w4, %2\n"
- "1:\n"
- : "=&r" (res), "=&r" (oldval), "+Q" (*(u16
*)ptr)
- : "Ir" (old), "r" (new)
- : "cc");
- } while (res);
- break;
-
+ return __cmpxchg_case_2(ptr, old, new);
case 4:
- do {
- asm volatile("// __cmpxchg4\n"
- " ldxr %w1, %2\n"
- " mov %w0, #0\n"
- " cmp %w1, %w3\n"
- " b.ne 1f\n"
- " stxr %w0, %w4, %2\n"
- "1:\n"
- : "=&r" (res), "=&r" (oldval), "+Q" (*(u32
*)ptr)
- : "Ir" (old), "r" (new)
- : "cc");
- } while (res);
- break;
-
+ return __cmpxchg_case_4(ptr, old, new);
case 8:
- do {
- asm volatile("// __cmpxchg8\n"
- " ldxr %1, %2\n"
- " mov %w0, #0\n"
- " cmp %1, %3\n"
- " b.ne 1f\n"
- " stxr %w0, %4, %2\n"
- "1:\n"
- : "=&r" (res), "=&r" (oldval), "+Q" (*(u64
*)ptr)
- : "Ir" (old), "r" (new)
- : "cc");
- } while (res);
- break;
-
+ return __cmpxchg_case_8(ptr, old, new);
default:
- __bad_cmpxchg(ptr, size);
- oldval = 0;
+ return __bad_cmpxchg(ptr, size);
}
- return oldval;
+ ASSERT_UNREACHABLE();
}
static inline unsigned long __cmpxchg_mb(volatile void *ptr, unsigned long old,
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.9
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