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x86emul: fix {,i}mul and {,i}div
Commit a3db233ede ("x86emul: use DstEax also for {,I}{MUL,DIV}") went
a little too far: DstEax and SrcEax weren't really meant to be used
together with ModRM - they assume modrm_reg remains zero by the time
the destination / source register pointer gets calculated. Don't fully
undo that commit though, but instead just correct the register pointer,
and don't use dst.val as input for mul and imul (div and idiv did avoid
that already).
Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Jan Beulich committed
1 parent
eabe1c39d1
commit
75066cd4ea
1 file changed
+12
-8
@@ -3845,18 +3845,19 @@ x86_emulate(
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emulate_1op("neg", dst, _regs.eflags);
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break;
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case 4: /* mul */
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dst.reg = (unsigned long *)&_regs.eax;
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_regs.eflags &= ~(EFLG_OF|EFLG_CF);
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switch ( dst.bytes )
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{
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case 1:
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dst.val = (uint8_t)dst.val;
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dst.val = (uint8_t)_regs.eax;
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dst.val *= src.val;
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if ( (uint8_t)dst.val != (uint16_t)dst.val )
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_regs.eflags |= EFLG_OF|EFLG_CF;
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dst.bytes = 2;
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break;
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case 2:
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dst.val = (uint16_t)dst.val;
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dst.val = (uint16_t)_regs.eax;
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dst.val *= src.val;
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if ( (uint16_t)dst.val != (uint32_t)dst.val )
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_regs.eflags |= EFLG_OF|EFLG_CF;
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@@ -3864,7 +3865,7 @@ x86_emulate(
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break;
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#ifdef __x86_64__
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case 4:
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dst.val = (uint32_t)dst.val;
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dst.val = _regs._eax;
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dst.val *= src.val;
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if ( (uint32_t)dst.val != dst.val )
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_regs.eflags |= EFLG_OF|EFLG_CF;
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@@ -3873,7 +3874,7 @@ x86_emulate(
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#endif
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default:
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u[0] = src.val;
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u[1] = dst.val;
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u[1] = _regs.eax;
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if ( mul_dbl(u) )
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_regs.eflags |= EFLG_OF|EFLG_CF;
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_regs.edx = u[1];
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@@ -3882,12 +3883,13 @@ x86_emulate(
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}
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break;
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case 5: /* imul */
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dst.reg = (unsigned long *)&_regs.eax;
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imul:
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_regs.eflags &= ~(EFLG_OF|EFLG_CF);
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switch ( dst.bytes )
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{
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case 1:
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dst.val = (int8_t)src.val * (int8_t)dst.val;
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dst.val = (int8_t)src.val * (int8_t)_regs.eax;
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if ( (int8_t)dst.val != (int16_t)dst.val )
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_regs.eflags |= EFLG_OF|EFLG_CF;
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ASSERT(b > 0x6b);
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@@ -3895,7 +3897,7 @@ x86_emulate(
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break;
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case 2:
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dst.val = ((uint32_t)(int16_t)src.val *
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(uint32_t)(int16_t)dst.val);
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(uint32_t)(int16_t)_regs.eax);
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if ( (int16_t)dst.val != (int32_t)dst.val )
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_regs.eflags |= EFLG_OF|EFLG_CF;
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if ( b > 0x6b )
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@@ -3904,7 +3906,7 @@ x86_emulate(
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#ifdef __x86_64__
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case 4:
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dst.val = ((uint64_t)(int32_t)src.val *
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(uint64_t)(int32_t)dst.val);
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(uint64_t)(int32_t)_regs.eax);
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if ( (int32_t)dst.val != dst.val )
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_regs.eflags |= EFLG_OF|EFLG_CF;
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if ( b > 0x6b )
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@@ -3913,7 +3915,7 @@ x86_emulate(
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#endif
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default:
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u[0] = src.val;
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u[1] = dst.val;
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u[1] = _regs.eax;
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if ( imul_dbl(u) )
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_regs.eflags |= EFLG_OF|EFLG_CF;
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if ( b > 0x6b )
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@@ -3923,6 +3925,7 @@ x86_emulate(
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}
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break;
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case 6: /* div */
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dst.reg = (unsigned long *)&_regs.eax;
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switch ( src.bytes )
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{
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case 1:
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@@ -3968,6 +3971,7 @@ x86_emulate(
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}
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break;
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case 7: /* idiv */
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dst.reg = (unsigned long *)&_regs.eax;
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switch ( src.bytes )
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{
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case 1:
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