From f718d426d7e42eec6e5d2932f52a51de23bd3b30 Mon Sep 17 00:00:00 2001 From: Matt Brown Date: Wed, 24 May 2017 09:45:59 +1000 Subject: powerpc/lib/xor_vmx: Ensure no altivec code executes before enable_kernel_altivec() The xor_vmx.c file is used for the RAID5 xor operations. In these functions altivec is enabled to run the operation and then disabled. The code uses enable_kernel_altivec() around the core of the algorithm, however the whole file is built with -maltivec, so the compiler is within its rights to generate altivec code anywhere. This has been seen at least once in the wild: 0:mon> di $xor_altivec_2 c0000000000b97d0 3c4c01d9 addis r2,r12,473 c0000000000b97d4 3842db30 addi r2,r2,-9424 c0000000000b97d8 7c0802a6 mflr r0 c0000000000b97dc f8010010 std r0,16(r1) c0000000000b97e0 60000000 nop c0000000000b97e4 7c0802a6 mflr r0 c0000000000b97e8 faa1ffa8 std r21,-88(r1) ... c0000000000b981c f821ff41 stdu r1,-192(r1) c0000000000b9820 7f8101ce stvx v28,r1,r0 <-- POP c0000000000b9824 38000030 li r0,48 c0000000000b9828 7fa101ce stvx v29,r1,r0 ... c0000000000b984c 4bf6a06d bl c0000000000238b8 # enable_kernel_altivec This patch splits the non-altivec code into xor_vmx_glue.c which calls the altivec functions in xor_vmx.c. By compiling xor_vmx_glue.c without -maltivec we can guarantee that altivec instruction will not be executed outside of the enable/disable block. Signed-off-by: Matt Brown [mpe: Rework change log and include disassembly] Signed-off-by: Michael Ellerman --- arch/powerpc/lib/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/powerpc/lib/Makefile') diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile index 2c56f4636c2b..3c3146ba62da 100644 --- a/arch/powerpc/lib/Makefile +++ b/arch/powerpc/lib/Makefile @@ -37,7 +37,7 @@ obj-$(CONFIG_PPC_LIB_RHEAP) += rheap.o obj-$(CONFIG_FTR_FIXUP_SELFTEST) += feature-fixups-test.o -obj-$(CONFIG_ALTIVEC) += xor_vmx.o +obj-$(CONFIG_ALTIVEC) += xor_vmx.o xor_vmx_glue.o CFLAGS_xor_vmx.o += -maltivec $(call cc-option,-mabi=altivec) obj-$(CONFIG_PPC64) += $(obj64-y) -- cgit v1.2.3