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Message-Id: <1423767879-31691-1-git-send-email-dvlasenk@redhat.com>
Date: Thu, 12 Feb 2015 20:04:39 +0100
From: Denys Vlasenko <dvlasenk@...hat.com>
To: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>,
"Frank Ch. Eigler" <fche@...hat.com>,
Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
Ananth N Mavinakayanahalli <ananth@...ibm.com>,
Jim Keniston <jkenisto@...ux.vnet.ibm.com>,
Oleg Nesterov <oleg@...hat.com>,
Andi Kleen <andi@...stfloor.org>,
Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org
Subject: [PATCH] x86: insn 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@...hat.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc: Frank Ch. Eigler <fche@...hat.com>
Cc: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com>
Cc: Jim Keniston <jkenisto@...ux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Andi Kleen <andi@...stfloor.org>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: linux-kernel@...r.kernel.org
---
Masami, you were ok with this patch last time it was posted.
Can you "officially" add your Acked-By?
arch/x86/lib/insn.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/arch/x86/lib/insn.c b/arch/x86/lib/insn.c
index 54fcffe..829ca4c 100644
--- a/arch/x86/lib/insn.c
+++ b/arch/x86/lib/insn.c
@@ -163,6 +163,12 @@ 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;
}
--
1.8.1.4
--
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