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authorMichael Ellerman <mpe@ellerman.id.au>2018-04-12 22:24:45 +1000
committerMichael Ellerman <mpe@ellerman.id.au>2018-04-13 23:51:44 +1000
commit81b654c273914704a4bdf580f28d67aaba1094e4 (patch)
tree69fe2b36a2c28a60ab594de166612bcb61bfd017 /arch/powerpc/kernel/dt_cpu_ftrs.c
parent2675c13b293a007b7b7f8229514126bd23df09a7 (diff)
powerpc/64s: Fix CPU_FTRS_ALWAYS vs DT CPU features
The cpu_has_feature() mechanism has an optimisation where at build time we construct a mask of the CPU feature bits that will always be true for the given .config, based on the platform/bitness/etc. that we are building for. That is incompatible with DT CPU features, where the set of CPU features is dependent on feature flags that are given to us by firmware. The result is that some feature bits can not be *disabled* by DT CPU features. Or more accurately, they can be disabled but they will still appear in the ALWAYS mask, meaning cpu_has_feature() will always return true for them. In the past this hasn't really been a problem because on Book3S 64 (where we support DT CPU features), the set of ALWAYS bits has been very small. That was because we always built for POWER4 and later, meaning the set of common bits was small. The only bit that could be cleared by DT CPU features that was also in the ALWAYS mask was CPU_FTR_NODSISRALIGN, and that was only used in the alignment handler to create a fake DSISR. That code was itself deleted in 31bfdb036f12 ("powerpc: Use instruction emulation infrastructure to handle alignment faults") (Sep 2017). However the set of ALWAYS features changed with the recent commit db5ae1c155af ("powerpc/64s: Refine feature sets for little endian builds") which restricted the set of feature flags when building little endian to Power7 or later. That caused the ALWAYS mask to become much larger for little endian builds. The result is that the following feature bits can currently not be *disabled* by DT CPU features: CPU_FTR_REAL_LE, CPU_FTR_MMCRA, CPU_FTR_CTRL, CPU_FTR_SMT, CPU_FTR_PURR, CPU_FTR_SPURR, CPU_FTR_DSCR, CPU_FTR_PKEY, CPU_FTR_VMX_COPY, CPU_FTR_CFAR, CPU_FTR_HAS_PPR. To fix it we need to mask the set of ALWAYS features with the base set of DT CPU features, ie. the features that are always enabled by DT CPU features. That way there are no bits in the ALWAYS mask that are not also always set by DT CPU features. Fixes: db5ae1c155af ("powerpc/64s: Refine feature sets for little endian builds") Reviewed-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kernel/dt_cpu_ftrs.c')
-rw-r--r--arch/powerpc/kernel/dt_cpu_ftrs.c14
1 files changed, 1 insertions, 13 deletions
diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c
index e88fbb1fdb8f..8ab51f6ca03a 100644
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -53,18 +53,6 @@ struct dt_cpu_feature {
int disabled;
};
-#define CPU_FTRS_BASE \
- (CPU_FTR_LWSYNC | \
- CPU_FTR_FPU_UNAVAILABLE |\
- CPU_FTR_NODSISRALIGN |\
- CPU_FTR_NOEXECUTE |\
- CPU_FTR_COHERENT_ICACHE | \
- CPU_FTR_STCX_CHECKS_ADDRESS |\
- CPU_FTR_POPCNTB | CPU_FTR_POPCNTD | \
- CPU_FTR_DAWR | \
- CPU_FTR_ARCH_206 |\
- CPU_FTR_ARCH_207S)
-
#define MMU_FTRS_HASH_BASE (MMU_FTRS_POWER8)
#define COMMON_USER_BASE (PPC_FEATURE_32 | PPC_FEATURE_64 | \
@@ -124,7 +112,7 @@ static char dt_cpu_name[64];
static struct cpu_spec __initdata base_cpu_spec = {
.cpu_name = NULL,
- .cpu_features = CPU_FTRS_BASE,
+ .cpu_features = CPU_FTRS_DT_CPU_BASE,
.cpu_user_features = COMMON_USER_BASE,
.cpu_user_features2 = COMMON_USER2_BASE,
.mmu_features = 0,