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authorDenys Vlasenko <dvlasenk@redhat.com>2015-02-12 20:04:39 +0100
committerIngo Molnar <mingo@kernel.org>2015-02-18 21:01:50 +0100
commit8a764a875fe3cf3a83296bacd00bfc41917e95e2 (patch)
tree49cfac09cb27568b93d8d384af495650e99988d9 /arch/x86/lib/insn.c
parente07e0d4cb0c4bfe822ec8491cc06269096a38bea (diff)
x86/asm/decoder: Create artificial 3rd byte for 2-byte VEX
Before this patch, users need to do this to fetch vex.vvvv: if (insn->vex_prefix.nbytes == 2) { vex_vvvv = ((insn->vex_prefix.bytes[1] >> 3) & 0xf) ^ 0xf; } if (insn->vex_prefix.nbytes == 3) { vex_vvvv = ((insn->vex_prefix.bytes[2] >> 3) & 0xf) ^ 0xf; } Make it so that insn->vex_prefix.bytes[2] always contains vex.wvvvvLpp bits. Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com> Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Frank Ch. Eigler <fche@redhat.com> Cc: Jim Keniston <jkenisto@linux.vnet.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/1423767879-31691-1-git-send-email-dvlasenk@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/lib/insn.c')
-rw-r--r--arch/x86/lib/insn.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/x86/lib/insn.c b/arch/x86/lib/insn.c
index 1313ae6b478b..5ea00ddc1825 100644
--- a/arch/x86/lib/insn.c
+++ b/arch/x86/lib/insn.c
@@ -164,6 +164,12 @@ found:
/* VEX.W overrides opnd_size */
insn->opnd_bytes = 8;
} else {
+ /*
+ * For VEX2, fake VEX3-like byte#2.
+ * Makes it easier to decode vex.W, vex.vvvv,
+ * vex.L and vex.pp. Masking with 0x7f sets vex.W == 0.
+ */
+ insn->vex_prefix.bytes[2] = b2 & 0x7f;
insn->vex_prefix.nbytes = 2;
insn->next_byte += 2;
}