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i386: hvf: Fix register refs if REX is present

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According to Intel(R)64 and IA-32 Architectures Software Developer's
Manual, the following one-byte registers should be fetched when REX
prefix is present (sorted by reg encoding index):
AL, CL, DL, BL, SPL, BPL, SIL, DIL, R8L - R15L

The first 8 are fetched if REX.R is zero, the last 8 if non-zero.

The following registers should be fetched for instructions without REX
prefix (also sorted by reg encoding index):
AL, CL, DL, BL, AH, CH, DH, BH

Current emulation code doesn't handle accesses to SPL, BPL, SIL, DIL
when REX is present, thefore an instruction 40883e "mov %dil,(%rsi)" is
decoded as "mov %bh,(%rsi)".

That caused an infinite loop in vp_reset:
https://lists.gnu.org/archive/html/qemu-devel/2018-10/msg03293.html

Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
Message-Id: <20181018134401.44471-1-r.bolshakov@yadro.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Roman Bolshakov 2018-10-18 16:44:01 +03:00 • committed by Paolo Bonzini
parent 6b7a98303b
commit b4e1af8961
2 changed files with 42 additions and 31 deletions
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6
target/i386/hvf/x86_decode.h
View file

@ -303,8 +303,10 @@ uint64_t sign(uint64_t val, int size);
uint32_t decode_instruction(CPUX86State *env, struct x86_decode *decode);
target_ulong get_reg_ref(CPUX86State *env, int reg, int is_extended, int size);
target_ulong get_reg_val(CPUX86State *env, int reg, int is_extended, int size);
target_ulong get_reg_ref(CPUX86State *env, int reg, int rex, int is_extended,
int size);
target_ulong get_reg_val(CPUX86State *env, int reg, int rex, int is_extended,
int size);
void calc_modrm_operand(CPUX86State *env, struct x86_decode *decode,
struct x86_decode_op *op);
target_ulong decode_linear_addr(CPUX86State *env, struct x86_decode *decode,