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| author |   Michael Ellerman <mpe@ellerman.id.au> | 2021-02-18 23:30:58 +1100 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2021-03-01 12:33:31 +1100 |
| commit | eead089311f4d935ab5d1d8fbb0c42ad44699ada (patch) | |
| tree | 168d406a4752ba18f369c32e5be0540d89e07885 /arch/powerpc/include/asm/dcr-native.h | |
| parent | Linux 5.12-rc1 (diff) | |
| download | wireguard-linux-eead089311f4d935ab5d1d8fbb0c42ad44699ada.tar.xz wireguard-linux-eead089311f4d935ab5d1d8fbb0c42ad44699ada.zip | |
powerpc/4xx: Fix build errors from mfdcr()
lkp reported a build error in fsp2.o:
CC arch/powerpc/platforms/44x/fsp2.o
{standard input}:577: Error: unsupported relocation against base
Which comes from:
pr_err("GESR0: 0x%08x\n", mfdcr(base + PLB4OPB_GESR0));
Where our mfdcr() macro is stringifying "base + PLB4OPB_GESR0", and
passing that to the assembler, which obviously doesn't work.
The mfdcr() macro already checks that the argument is constant using
__builtin_constant_p(), and if not calls the out-of-line version of
mfdcr(). But in this case GCC is smart enough to notice that "base +
PLB4OPB_GESR0" will be constant, even though it's not something we can
immediately stringify into a register number.
Segher pointed out that passing the register number to the inline asm
as a constant would be better, and in fact it fixes the build error,
presumably because it gives GCC a chance to resolve the value.
While we're at it, change mtdcr() similarly.
Reported-by: kernel test robot <lkp@intel.com>
Suggested-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Feng Tang <feng.tang@intel.com>
Link: https://lore.kernel.org/r/20210218123058.748882-1-mpe@ellerman.id.au
Diffstat (limited to 'arch/powerpc/include/asm/dcr-native.h')
| -rw-r--r-- | arch/powerpc/include/asm/dcr-native.h | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/powerpc/include/asm/dcr-native.h b/arch/powerpc/include/asm/dcr-native.h index 7141ccea8c94..a92059964579 100644 --- a/arch/powerpc/include/asm/dcr-native.h +++ b/arch/powerpc/include/asm/dcr-native.h @@ -53,8 +53,8 @@ static inline void mtdcrx(unsigned int reg, unsigned int val) #define mfdcr(rn) \ ({unsigned int rval; \ if (__builtin_constant_p(rn) && rn < 1024) \ - asm volatile("mfdcr %0," __stringify(rn) \ - : "=r" (rval)); \ + asm volatile("mfdcr %0, %1" : "=r" (rval) \ + : "n" (rn)); \ else if (likely(cpu_has_feature(CPU_FTR_INDEXED_DCR))) \ rval = mfdcrx(rn); \ else \ @@ -64,8 +64,8 @@ static inline void mtdcrx(unsigned int reg, unsigned int val) #define mtdcr(rn, v) \ do { \ if (__builtin_constant_p(rn) && rn < 1024) \ - asm volatile("mtdcr " __stringify(rn) ",%0" \ - : : "r" (v)); \ + asm volatile("mtdcr %0, %1" \ + : : "n" (rn), "r" (v)); \ else if (likely(cpu_has_feature(CPU_FTR_INDEXED_DCR))) \ mtdcrx(rn, v); \ else \ |