Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
[POWERPC] Add "memory" clobber to MMIO accessors
Gcc might re-order MMIO accessors vs. surrounding consistent
memory accesses, which is a "bad thing", and could break drivers.
This fixes it by adding a "memory" clobber to the MMIO accessors,
which should prevent gcc from doing that reordering.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
authored by Benjamin Herrenschmidt and committed by Paul Mackerras cfab3bdf 732bee4c
+7
-5
include/asm-powerpc/io.h
+7
-5
include/asm-powerpc/io.h
···
100
100
{ \
101
101
type ret; \
102
102
__asm__ __volatile__("sync;" insn ";twi 0,%0,0;isync" \
103
-
: "=r" (ret) : "r" (addr), "m" (*addr)); \
103
+
: "=r" (ret) : "r" (addr), "m" (*addr) : "memory"); \
104
104
return ret; \
105
105
}
106
106
···
108
108
static inline void name(volatile type __iomem *addr, type val) \
109
109
{ \
110
110
__asm__ __volatile__("sync;" insn \
111
-
: "=m" (*addr) : "r" (val), "r" (addr)); \
112
-
IO_SET_SYNC_FLAG(); \
111
+
: "=m" (*addr) : "r" (val), "r" (addr) : "memory"); \
112
+
IO_SET_SYNC_FLAG(); \
113
113
}
114
114
115
115
···
333
333
" .long 3b,5b\n" \
334
334
".previous" \
335
335
: "=&r" (x) \
336
-
: "r" (port + _IO_BASE)); \
336
+
: "r" (port + _IO_BASE) \
337
+
: "memory"); \
337
338
return x; \
338
339
}
339
340
···
351
350
" .long 0b,2b\n" \
352
351
" .long 1b,2b\n" \
353
352
".previous" \
354
-
: : "r" (val), "r" (port + _IO_BASE)); \
353
+
: : "r" (val), "r" (port + _IO_BASE) \
354
+
: "memory"); \
355
355
}
356
356
357
357
__do_in_asm(_rec_inb, "lbzx")