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| author | Nicholas Piggin <npiggin@gmail.com> | 2016-10-13 05:43:52 +0200 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2016-11-14 01:11:51 +0100 |
| commit | f4329f2ecb149282fdfdd8830a936a56b1497a05 (patch) | |
| tree | 437623c6fe2f44a63a62e754fb423b84bd62967a | |
| parent | powerpc: Remove suspect CONFIG_PPC_BOOK3E #ifdefs in nohash/64/pgtable.h (diff) | |
| download | linux-f4329f2ecb149282fdfdd8830a936a56b1497a05.tar.xz linux-f4329f2ecb149282fdfdd8830a936a56b1497a05.zip | |
powerpc/64s: Reduce exception alignment
Exception handlers are aligned to 128 bytes (L1 cache) on 64s, which is
overkill. It can reduce the icache footprint of any individual exception
path. However taken as a whole, the expansion in icache footprint seems
likely to be counter-productive and cause more total misses.
Create IFETCH_ALIGN_SHIFT/BYTES, which should give optimal ifetch
alignment with much more reasonable alignment. This saves 1792 bytes
from head_64.o text with an allmodconfig build.
Other subarchitectures should define appropriate IFETCH_ALIGN_SHIFT
values if this becomes more widely used.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
| -rw-r--r-- | arch/powerpc/include/asm/cache.h | 3 | ||||
| -rw-r--r-- | arch/powerpc/include/asm/head-64.h | 8 | ||||
| -rw-r--r-- | arch/powerpc/kernel/exceptions-64s.S | 2 |
3 files changed, 8 insertions, 5 deletions
diff --git a/arch/powerpc/include/asm/cache.h b/arch/powerpc/include/asm/cache.h index ffbafbf76b19..7657aa897a38 100644 --- a/arch/powerpc/include/asm/cache.h +++ b/arch/powerpc/include/asm/cache.h @@ -20,12 +20,15 @@ #endif #else /* CONFIG_PPC64 */ #define L1_CACHE_SHIFT 7 +#define IFETCH_ALIGN_SHIFT 4 /* POWER8,9 */ #endif #define L1_CACHE_BYTES (1 << L1_CACHE_SHIFT) #define SMP_CACHE_BYTES L1_CACHE_BYTES +#define IFETCH_ALIGN_BYTES (1 << IFETCH_ALIGN_SHIFT) + #if defined(__powerpc64__) && !defined(__ASSEMBLY__) struct ppc64_caches { u32 dsize; /* L1 d-cache size */ diff --git a/arch/powerpc/include/asm/head-64.h b/arch/powerpc/include/asm/head-64.h index ab90c2fa1ea6..fca7033839a9 100644 --- a/arch/powerpc/include/asm/head-64.h +++ b/arch/powerpc/include/asm/head-64.h @@ -95,12 +95,12 @@ end_##sname: #define __FIXED_SECTION_ENTRY_BEGIN(sname, name, __align) \ USE_FIXED_SECTION(sname); \ - .align __align; \ + .balign __align; \ .global name; \ name: #define FIXED_SECTION_ENTRY_BEGIN(sname, name) \ - __FIXED_SECTION_ENTRY_BEGIN(sname, name, 0) + __FIXED_SECTION_ENTRY_BEGIN(sname, name, IFETCH_ALIGN_BYTES) #define FIXED_SECTION_ENTRY_BEGIN_LOCATION(sname, name, start) \ USE_FIXED_SECTION(sname); \ @@ -203,9 +203,9 @@ name: #define EXC_VIRT_END(name, start, end) \ FIXED_SECTION_ENTRY_END_LOCATION(virt_vectors, exc_virt_##start##_##name, end) -#define EXC_COMMON_BEGIN(name) \ +#define EXC_COMMON_BEGIN(name) \ USE_TEXT_SECTION(); \ - .align 7; \ + .balign IFETCH_ALIGN_BYTES; \ .global name; \ DEFINE_FIXED_SYMBOL(name); \ name: diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 08ba447a4b3d..50f0c5ab7e02 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -1403,7 +1403,7 @@ USE_TEXT_SECTION() /* * Hash table stuff */ - .align 7 + .balign IFETCH_ALIGN_BYTES do_hash_page: #ifdef CONFIG_PPC_STD_MMU_64 andis. r0,r4,0xa410 /* weird error? */ |