diff options
| author | Palmer Dabbelt <palmer@rivosinc.com> | 2024-01-10 09:54:29 -0800 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2024-01-11 07:36:30 -0800 |
| commit | 2e605741e9dd26426ba2475afaf5966d781bfbc6 (patch) | |
| tree | c8d43c19715f5899b92d0fe818ef69c5d47376d2 /arch/riscv/include/asm | |
| parent | 07df87c0f8815898cb994408c4b6dd542a1394b8 (diff) | |
| parent | 3690492612ecd2b3fd69f39f3a56f6313ea8ef8b (diff) | |
Merge patch series "riscv: errata: thead: use riscv_nonstd_cache_ops for CMO"
Jisheng Zhang <jszhang@kernel.org> says:
Previously, we use alternative mechanism to dynamically patch
the CMO operations for THEAD C906/C910 during boot for performance
reason. But as pointed out by Arnd, "there is already a significant
cost in accessing the invalidated cache lines afterwards, which is
likely going to be much higher than the cost of an indirect branch".
And indeed, there's no performance difference with GMAC and EMMC per
my test on Sipeed Lichee Pi 4A board.
Use riscv_nonstd_cache_ops for THEAD C906/C910 CMO to simplify
the alternative code, and to acchieve Arnd's goal -- "I think
moving the THEAD ops at the same level as all nonstandard operations
makes sense, but I'd still leave CMO as an explicit fast path that
avoids the indirect branch. This seems like the right thing to do both
for readability and for platforms on which the indirect branch has a
noticeable overhead."
To make bisect easy, I use two patches here: patch1 does the conversion
which just mimics current CMO behavior via. riscv_nonstd_cache_ops, I
assume no functionalities changes. patch2 uses T-HEAD PA based CMO
instructions so that we don't need to covert PA to VA.
* b4-shazam-merge:
riscv: errata: thead: use pa based instructions for CMO
riscv: errata: thead: use riscv_nonstd_cache_ops for CMO
Link: https://lore.kernel.org/r/20231114143338.2406-1-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Diffstat (limited to 'arch/riscv/include/asm')
| -rw-r--r-- | arch/riscv/include/asm/errata_list.h | 50 |
1 files changed, 6 insertions, 44 deletions
diff --git a/arch/riscv/include/asm/errata_list.h b/arch/riscv/include/asm/errata_list.h index 83ed25e43553..ea33288f8a25 100644 --- a/arch/riscv/include/asm/errata_list.h +++ b/arch/riscv/include/asm/errata_list.h @@ -24,9 +24,8 @@ #ifdef CONFIG_ERRATA_THEAD #define ERRATA_THEAD_PBMT 0 -#define ERRATA_THEAD_CMO 1 -#define ERRATA_THEAD_PMU 2 -#define ERRATA_THEAD_NUMBER 3 +#define ERRATA_THEAD_PMU 1 +#define ERRATA_THEAD_NUMBER 2 #endif #ifdef __ASSEMBLY__ @@ -94,54 +93,17 @@ asm volatile(ALTERNATIVE( \ #define ALT_THEAD_PMA(_val) #endif -/* - * th.dcache.ipa rs1 (invalidate, physical address) - * | 31 - 25 | 24 - 20 | 19 - 15 | 14 - 12 | 11 - 7 | 6 - 0 | - * 0000001 01010 rs1 000 00000 0001011 - * th.dache.iva rs1 (invalida, virtual address) - * 0000001 00110 rs1 000 00000 0001011 - * - * th.dcache.cpa rs1 (clean, physical address) - * | 31 - 25 | 24 - 20 | 19 - 15 | 14 - 12 | 11 - 7 | 6 - 0 | - * 0000001 01001 rs1 000 00000 0001011 - * th.dcache.cva rs1 (clean, virtual address) - * 0000001 00101 rs1 000 00000 0001011 - * - * th.dcache.cipa rs1 (clean then invalidate, physical address) - * | 31 - 25 | 24 - 20 | 19 - 15 | 14 - 12 | 11 - 7 | 6 - 0 | - * 0000001 01011 rs1 000 00000 0001011 - * th.dcache.civa rs1 (... virtual address) - * 0000001 00111 rs1 000 00000 0001011 - * - * th.sync.s (make sure all cache operations finished) - * | 31 - 25 | 24 - 20 | 19 - 15 | 14 - 12 | 11 - 7 | 6 - 0 | - * 0000000 11001 00000 000 00000 0001011 - */ -#define THEAD_INVAL_A0 ".long 0x0265000b" -#define THEAD_CLEAN_A0 ".long 0x0255000b" -#define THEAD_FLUSH_A0 ".long 0x0275000b" -#define THEAD_SYNC_S ".long 0x0190000b" - #define ALT_CMO_OP(_op, _start, _size, _cachesize) \ -asm volatile(ALTERNATIVE_2( \ - __nops(6), \ +asm volatile(ALTERNATIVE( \ + __nops(5), \ "mv a0, %1\n\t" \ "j 2f\n\t" \ "3:\n\t" \ CBO_##_op(a0) \ "add a0, a0, %0\n\t" \ "2:\n\t" \ - "bltu a0, %2, 3b\n\t" \ - "nop", 0, RISCV_ISA_EXT_ZICBOM, CONFIG_RISCV_ISA_ZICBOM, \ - "mv a0, %1\n\t" \ - "j 2f\n\t" \ - "3:\n\t" \ - THEAD_##_op##_A0 "\n\t" \ - "add a0, a0, %0\n\t" \ - "2:\n\t" \ - "bltu a0, %2, 3b\n\t" \ - THEAD_SYNC_S, THEAD_VENDOR_ID, \ - ERRATA_THEAD_CMO, CONFIG_ERRATA_THEAD_CMO) \ + "bltu a0, %2, 3b\n\t", \ + 0, RISCV_ISA_EXT_ZICBOM, CONFIG_RISCV_ISA_ZICBOM) \ : : "r"(_cachesize), \ "r"((unsigned long)(_start) & ~((_cachesize) - 1UL)), \ "r"((unsigned long)(_start) + (_size)) \ |