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 */