From: "Jan Beulich" <JBeulich@suse.com>
To: xen-devel <xen-devel@lists.xenproject.org>
Cc: George Dunlap <George.Dunlap@eu.citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Wei Liu <wei.liu2@citrix.com>
Subject: [PATCH 1/2] x86emul: simplify DstBitBase handling code
Date: Tue, 22 Nov 2016 07:20:22 -0700 [thread overview]
Message-ID: <583462360200007800120D60@prv-mh.provo.novell.com> (raw)
In-Reply-To: <58345F900200007800120D26@prv-mh.provo.novell.com>
[-- Attachment #1: Type: text/plain, Size: 2062 bytes --]
..., at once making it more obvious that even in the negative bit
offset case the resulting bit offset to be used by the inlined
instructions will always be constrained to the operand size of the
original instruction.
Also add a test case which would have failed without the XSA-195 fix.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
--- a/tools/tests/x86_emulator/test_x86_emulator.c
+++ b/tools/tests/x86_emulator/test_x86_emulator.c
@@ -431,6 +431,22 @@ int main(int argc, char **argv)
goto fail;
printf("okay\n");
+#ifdef __x86_64__
+ printf("%-40s", "Testing btcq %r8,(%r11)...");
+ instr[0] = 0x4d; instr[1] = 0x0f; instr[2] = 0xbb; instr[3] = 0x03;
+ regs.eflags = 0x200;
+ regs.rip = (unsigned long)&instr[0];
+ regs.r8 = (-1L << 40) + 1;
+ regs.r11 = (unsigned long)(res + (1L << 35));
+ rc = x86_emulate(&ctxt, &emulops);
+ if ( (rc != X86EMUL_OKAY) ||
+ (*res != 0x2233445C) ||
+ (regs.eflags != 0x201) ||
+ (regs.rip != (unsigned long)&instr[4]) )
+ goto fail;
+ printf("okay\n");
+#endif
+
res[0] = 0x12345678;
res[1] = 0x87654321;
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -2560,18 +2560,11 @@ x86_emulate(
else if ( op_bytes == 4 )
src.val = (int32_t)src.val;
if ( (long)src.val < 0 )
- {
- unsigned long byte_offset =
+ ea.mem.off -=
op_bytes + (((-src.val - 1) >> 3) & ~(op_bytes - 1L));
-
- ea.mem.off -= byte_offset;
- src.val = (byte_offset << 3) + src.val;
- }
else
- {
ea.mem.off += (src.val >> 3) & ~(op_bytes - 1L);
- src.val &= (op_bytes << 3) - 1;
- }
+ src.val &= (op_bytes << 3) - 1;
}
/* Becomes a normal DstMem operation from here on. */
d = (d & ~DstMask) | DstMem;
[-- Attachment #2: x86emul-bt-consolidate.patch --]
[-- Type: text/plain, Size: 2102 bytes --]
x86emul: simplify DstBitBase handling code
..., at once making it more obvious that even in the negative bit
offset case the resulting bit offset to be used by the inlined
instructions will always be constrained to the operand size of the
original instruction.
Also add a test case which would have failed without the XSA-195 fix.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
--- a/tools/tests/x86_emulator/test_x86_emulator.c
+++ b/tools/tests/x86_emulator/test_x86_emulator.c
@@ -431,6 +431,22 @@ int main(int argc, char **argv)
goto fail;
printf("okay\n");
+#ifdef __x86_64__
+ printf("%-40s", "Testing btcq %r8,(%r11)...");
+ instr[0] = 0x4d; instr[1] = 0x0f; instr[2] = 0xbb; instr[3] = 0x03;
+ regs.eflags = 0x200;
+ regs.rip = (unsigned long)&instr[0];
+ regs.r8 = (-1L << 40) + 1;
+ regs.r11 = (unsigned long)(res + (1L << 35));
+ rc = x86_emulate(&ctxt, &emulops);
+ if ( (rc != X86EMUL_OKAY) ||
+ (*res != 0x2233445C) ||
+ (regs.eflags != 0x201) ||
+ (regs.rip != (unsigned long)&instr[4]) )
+ goto fail;
+ printf("okay\n");
+#endif
+
res[0] = 0x12345678;
res[1] = 0x87654321;
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -2560,18 +2560,11 @@ x86_emulate(
else if ( op_bytes == 4 )
src.val = (int32_t)src.val;
if ( (long)src.val < 0 )
- {
- unsigned long byte_offset =
+ ea.mem.off -=
op_bytes + (((-src.val - 1) >> 3) & ~(op_bytes - 1L));
-
- ea.mem.off -= byte_offset;
- src.val = (byte_offset << 3) + src.val;
- }
else
- {
ea.mem.off += (src.val >> 3) & ~(op_bytes - 1L);
- src.val &= (op_bytes << 3) - 1;
- }
+ src.val &= (op_bytes << 3) - 1;
}
/* Becomes a normal DstMem operation from here on. */
d = (d & ~DstMask) | DstMem;
[-- Attachment #3: Type: text/plain, Size: 127 bytes --]
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next prev parent reply other threads:[~2016-11-22 14:20 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-22 14:09 [PATCH 0/2] x86emul: recent XSA follow-up Jan Beulich
2016-11-22 14:20 ` Jan Beulich [this message]
2016-11-22 14:23 ` [PATCH 1/2] x86emul: simplify DstBitBase handling code Andrew Cooper
2016-11-22 14:20 ` [PATCH 2/2] x86emul: in_longmode() should not ignore ->read_msr() errors Jan Beulich
2016-11-22 14:25 ` Andrew Cooper
2016-11-23 14:14 ` [PATCH 0/2] x86emul: recent XSA follow-up Wei Liu
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