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s390/cmpxchg: get rid of gcc atomic builtins

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s390 is the only architecture in the kernel which makes use of gcc's
atomic builtin functions. Even though I don't see any technical
problem with that right now, remove this code and open-code
compare-and-swap loops again, like every other architecture is doing
it also.
We can switch to a generic implementation when other architectures are
doing that also.

See also https://lwn.net/Articles/586838/ for forther details.

This basically reverts commit f318a1229b ("s390/cmpxchg: use
compiler builtins").

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Heiko Carstens 2021-04-06 14:51:48 +02:00
parent b23eb636d7
commit d2b1f6d2d3
1 changed files with 150 additions and 15 deletions
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165
arch/s390/include/asm/cmpxchg.h
View File

@ -12,26 +12,163 @@
#include <linux/types.h>
#include <linux/bug.h>
void __xchg_called_with_bad_pointer(void);
static inline unsigned long __xchg(unsigned long x, void *ptr, int size)
{
unsigned long addr, old;
int shift;
switch (size) {
case 1:
addr = (unsigned long) ptr;
shift = (3 ^ (addr & 3)) << 3;
addr ^= addr & 3;
asm volatile(
" l %0,%1\n"
"0: lr 0,%0\n"
" nr 0,%3\n"
" or 0,%2\n"
" cs %0,0,%1\n"
" jl 0b\n"
: "=&d" (old), "+Q" (*(int *) addr)
: "d" ((x & 0xff) << shift), "d" (~(0xff << shift))
: "memory", "cc", "0");
return old >> shift;
case 2:
addr = (unsigned long) ptr;
shift = (2 ^ (addr & 2)) << 3;
addr ^= addr & 2;
asm volatile(
" l %0,%1\n"
"0: lr 0,%0\n"
" nr 0,%3\n"
" or 0,%2\n"
" cs %0,0,%1\n"
" jl 0b\n"
: "=&d" (old), "+Q" (*(int *) addr)
: "d" ((x & 0xffff) << shift), "d" (~(0xffff << shift))
: "memory", "cc", "0");
return old >> shift;
case 4:
asm volatile(
" l %0,%1\n"
"0: cs %0,%2,%1\n"
" jl 0b\n"
: "=&d" (old), "+Q" (*(int *) ptr)
: "d" (x)
: "memory", "cc");
return old;
case 8:
asm volatile(
" lg %0,%1\n"
"0: csg %0,%2,%1\n"
" jl 0b\n"
: "=&d" (old), "+S" (*(long *) ptr)
: "d" (x)
: "memory", "cc");
return old;
}
__xchg_called_with_bad_pointer();
return x;
}
#define xchg(ptr, x) \
({ \
__typeof__(*(ptr)) __ret; \
\
__ret = (__typeof__(*(ptr))) \
__xchg((unsigned long)(x), (void *)(ptr), sizeof(*(ptr))); \
__ret; \
})
void __cmpxchg_called_with_bad_pointer(void);
static inline unsigned long __cmpxchg(void *ptr, unsigned long old,
unsigned long new, int size)
{
unsigned long addr, prev, tmp;
int shift;
switch (size) {
case 1:
addr = (unsigned long) ptr;
shift = (3 ^ (addr & 3)) << 3;
addr ^= addr & 3;
asm volatile(
" l %0,%2\n"
"0: nr %0,%5\n"
" lr %1,%0\n"
" or %0,%3\n"
" or %1,%4\n"
" cs %0,%1,%2\n"
" jnl 1f\n"
" xr %1,%0\n"
" nr %1,%5\n"
" jnz 0b\n"
"1:"
: "=&d" (prev), "=&d" (tmp), "+Q" (*(int *) addr)
: "d" ((old & 0xff) << shift),
"d" ((new & 0xff) << shift),
"d" (~(0xff << shift))
: "memory", "cc");
return prev >> shift;
case 2:
addr = (unsigned long) ptr;
shift = (2 ^ (addr & 2)) << 3;
addr ^= addr & 2;
asm volatile(
" l %0,%2\n"
"0: nr %0,%5\n"
" lr %1,%0\n"
" or %0,%3\n"
" or %1,%4\n"
" cs %0,%1,%2\n"
" jnl 1f\n"
" xr %1,%0\n"
" nr %1,%5\n"
" jnz 0b\n"
"1:"
: "=&d" (prev), "=&d" (tmp), "+Q" (*(int *) addr)
: "d" ((old & 0xffff) << shift),
"d" ((new & 0xffff) << shift),
"d" (~(0xffff << shift))
: "memory", "cc");
return prev >> shift;
case 4:
asm volatile(
" cs %0,%3,%1\n"
: "=&d" (prev), "+Q" (*(int *) ptr)
: "0" (old), "d" (new)
: "memory", "cc");
return prev;
case 8:
asm volatile(
" csg %0,%3,%1\n"
: "=&d" (prev), "+S" (*(long *) ptr)
: "0" (old), "d" (new)
: "memory", "cc");
return prev;
}
__cmpxchg_called_with_bad_pointer();
return old;
}
#define cmpxchg(ptr, o, n) \
({ \
__typeof__(*(ptr)) __o = (o); \
__typeof__(*(ptr)) __n = (n); \
(__typeof__(*(ptr))) __sync_val_compare_and_swap((ptr),__o,__n);\
__typeof__(*(ptr)) __ret; \
\
__ret = (__typeof__(*(ptr))) \
__cmpxchg((ptr), (unsigned long)(o), \
(unsigned long)(n), sizeof(*(ptr))); \
__ret; \
})
#define cmpxchg64 cmpxchg
#define cmpxchg_local cmpxchg
#define cmpxchg64_local cmpxchg
#define cmpxchg64_local cmpxchg
#define xchg(ptr, x) \
({ \
__typeof__(ptr) __ptr = (ptr); \
__typeof__(*(ptr)) __old; \
do { \
__old = *__ptr; \
} while (!__sync_bool_compare_and_swap(__ptr, __old, x)); \
__old; \
})
#define system_has_cmpxchg_double() 1
#define __cmpxchg_double(p1, p2, o1, o2, n1, n2) \
({ \
@ -61,6 +198,4 @@
__cmpxchg_double(__p1, __p2, o1, o2, n1, n2); \
})
#define system_has_cmpxchg_double() 1
#endif /* __ASM_CMPXCHG_H */