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| author | Rajalakshmi Srinivasaraghavan <raji@linux.vnet.ibm.com> | 2017-09-19 13:55:49 +0530 |
|---|---|---|
| committer | Rajalakshmi Srinivasaraghavan <raji@linux.vnet.ibm.com> | 2017-09-19 13:55:49 +0530 |
| commit | bd17ba29eb5cb4ec7251c1ed0b4dcd7d287c0c0c (patch) | |
| tree | 7be77d387aac0fb4d0140211fadf6002c8b6f9e7 | |
| parent | 6d9b0b5a22738e100b57bdd593d799abac4949d7 (diff) | |
| download | glibc-bd17ba29eb5cb4ec7251c1ed0b4dcd7d287c0c0c.tar.gz | |
powerpc: Avoid misaligned stores in memset
As per the section "3.1.4.2 Alignment Interrupts" of the "POWER8 Processor
User's Manual for the Single-Chip Module", alignment interrupt is reported
for misaligned stores in Caching-inhibited storage. As memset is used in
some drivers for DMA (like xorg), this patch avoids misaligned stores for
sizes less than 8 in memset.
| -rw-r--r-- | ChangeLog | 4 | ||||
| -rw-r--r-- | sysdeps/powerpc/powerpc64/power8/memset.S | 70 |
2 files changed, 72 insertions, 2 deletions
@@ -1,3 +1,7 @@ +2017-09-19 Rajalakshmi Srinivasaraghavan <raji@linux.vnet.ibm.com> + + * sysdeps/powerpc/powerpc64/power8/memset.S: Avoid misaligned stores. + 2017-09-18 Joseph Myers <joseph@codesourcery.com> * sysdeps/ieee754/ldbl-opt/w_exp10l_compat.c [LIBM_SVID_COMPAT && diff --git a/sysdeps/powerpc/powerpc64/power8/memset.S b/sysdeps/powerpc/powerpc64/power8/memset.S index 369b95894a..5482801717 100644 --- a/sysdeps/powerpc/powerpc64/power8/memset.S +++ b/sysdeps/powerpc/powerpc64/power8/memset.S @@ -377,7 +377,10 @@ L(write_LT_32): subf r5,r0,r5 2: bf 30,1f - sth r4,0(r10) + /* Use stb instead of sth because it doesn't generate + alignment interrupts on cache-inhibited storage. */ + stb r4,0(r10) + stb r4,1(r10) addi r10,r10,2 1: bf 31,L(end_4bytes_alignment) @@ -437,11 +440,74 @@ L(tail5): /* Handles copies of 0~8 bytes. */ .align 4 L(write_LE_8): - bne cr6,L(tail4) + bne cr6,L(LE7_tail4) + /* If input is word aligned, use stw, else use stb. */ + andi. r0,r10,3 + bne L(8_unalign) stw r4,0(r10) stw r4,4(r10) blr + + /* Unaligned input and size is 8. */ + .align 4 +L(8_unalign): + andi. r0,r10,1 + beq L(8_hwalign) + stb r4,0(r10) + sth r4,1(r10) + sth r4,3(r10) + sth r4,5(r10) + stb r4,7(r10) + blr + + /* Halfword aligned input and size is 8. */ + .align 4 +L(8_hwalign): + sth r4,0(r10) + sth r4,2(r10) + sth r4,4(r10) + sth r4,6(r10) + blr + + .align 4 + /* Copies 4~7 bytes. */ +L(LE7_tail4): + /* Use stb instead of sth because it doesn't generate + alignment interrupts on cache-inhibited storage. */ + bf 29,L(LE7_tail2) + stb r4,0(r10) + stb r4,1(r10) + stb r4,2(r10) + stb r4,3(r10) + bf 30,L(LE7_tail5) + stb r4,4(r10) + stb r4,5(r10) + bflr 31 + stb r4,6(r10) + blr + + .align 4 + /* Copies 2~3 bytes. */ +L(LE7_tail2): + bf 30,1f + stb r4,0(r10) + stb r4,1(r10) + bflr 31 + stb r4,2(r10) + blr + + .align 4 +L(LE7_tail5): + bflr 31 + stb r4,4(r10) + blr + + .align 4 +1: bflr 31 + stb r4,0(r10) + blr + END_GEN_TB (MEMSET,TB_TOCLESS) libc_hidden_builtin_def (memset) |