This is a note to let you know that I've just added the patch titled
powerpc/sstep: Fix VSX instruction emulation
to the 5.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
powerpc-sstep-fix-vsx-instruction-emulation.patch
and it can be found in the queue-5.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 22a7402d7e7b8ac89e752a91505da72ed52d29a1
Author: Jordan Niethe <jniethe5@xxxxxxxxx>
Date: Thu Feb 25 14:19:46 2021 +1100
powerpc/sstep: Fix VSX instruction emulation
[ Upstream commit 5c88a17e15795226b56d83f579cbb9b7a4864f79 ]
Commit af99da74333b ("powerpc/sstep: Support VSX vector paired storage
access instructions") added loading and storing 32 word long data into
adjacent VSRs. However the calculation used to determine if two VSRs
needed to be loaded/stored inadvertently prevented the load/storing
taking place for instructions with a data length less than 16 words.
This causes the emulation to not function correctly, which can be seen
by the alignment_handler selftest:
$ ./alignment_handler
[snip]
test: test_alignment_handler_vsx_207
tags: git_version:powerpc-5.12-1-0-g82d2c16b350f
VSX: 2.07B
Doing lxsspx: PASSED
Doing lxsiwax: FAILED: Wrong Data
Doing lxsiwzx: PASSED
Doing stxsspx: PASSED
Doing stxsiwx: PASSED
failure: test_alignment_handler_vsx_207
test: test_alignment_handler_vsx_300
tags: git_version:powerpc-5.12-1-0-g82d2c16b350f
VSX: 3.00B
Doing lxsd: PASSED
Doing lxsibzx: PASSED
Doing lxsihzx: PASSED
Doing lxssp: FAILED: Wrong Data
Doing lxv: PASSED
Doing lxvb16x: PASSED
Doing lxvh8x: PASSED
Doing lxvx: PASSED
Doing lxvwsx: FAILED: Wrong Data
Doing lxvl: PASSED
Doing lxvll: PASSED
Doing stxsd: PASSED
Doing stxsibx: PASSED
Doing stxsihx: PASSED
Doing stxssp: PASSED
Doing stxv: PASSED
Doing stxvb16x: PASSED
Doing stxvh8x: PASSED
Doing stxvx: PASSED
Doing stxvl: PASSED
Doing stxvll: PASSED
failure: test_alignment_handler_vsx_300
[snip]
Fix this by making sure all VSX instruction emulation correctly
load/store from the VSRs.
Fixes: af99da74333b ("powerpc/sstep: Support VSX vector paired storage access instructions")
Signed-off-by: Jordan Niethe <jniethe5@xxxxxxxxx>
Reviewed-by: Ravi Bangoria <ravi.bangoria@xxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210225031946.1458206-1-jniethe5@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index bb5c20d4ca91..c6aebc149d14 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -904,7 +904,7 @@ static nokprobe_inline int do_vsx_load(struct instruction_op *op,
if (!address_ok(regs, ea, size) || copy_mem_in(mem, ea, size, regs))
return -EFAULT;
- nr_vsx_regs = size / sizeof(__vector128);
+ nr_vsx_regs = max(1ul, size / sizeof(__vector128));
emulate_vsx_load(op, buf, mem, cross_endian);
preempt_disable();
if (reg < 32) {
@@ -951,7 +951,7 @@ static nokprobe_inline int do_vsx_store(struct instruction_op *op,
if (!address_ok(regs, ea, size))
return -EFAULT;
- nr_vsx_regs = size / sizeof(__vector128);
+ nr_vsx_regs = max(1ul, size / sizeof(__vector128));
preempt_disable();
if (reg < 32) {
/* FP regs + extensions */
