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x86: xen: insn: Decode Xen and KVM emulate-prefix signature

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Decode Xen and KVM's emulate-prefix signature by x86 insn decoder.
It is called "prefix" but actually not x86 instruction prefix, so
this adds insn.emulate_prefix_size field instead of reusing
insn.prefixes.

If x86 decoder finds a special sequence of instructions of
XEN_EMULATE_PREFIX and 'ud2a; .ascii "kvm"', it just counts the
length, set insn.emulate_prefix_size and fold it with the next
instruction. In other words, the signature and the next instruction
is treated as a single instruction.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: x86@kernel.org
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: xen-devel@lists.xenproject.org
Cc: Randy Dunlap <rdunlap@infradead.org>
Link: https://lkml.kernel.org/r/156777564986.25081.4964537658500952557.stgit@devnote2
This commit is contained in:
Masami Hiramatsu
2019-09-06 22:14:10 +09:00
committed by Peter Zijlstra
parent b3dc0695fa
commit 4d65adfcd1
7 changed files with 98 additions and 2 deletions
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6
tools/arch/x86/include/asm/insn.h
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@@ -45,6 +45,7 @@ struct insn {
struct insn_field immediate2; /* for 64bit imm or seg16 */
};
int emulate_prefix_size;
insn_attr_t attr;
unsigned char opnd_bytes;
unsigned char addr_bytes;
@@ -128,6 +129,11 @@ static inline int insn_is_evex(struct insn *insn)
return (insn->vex_prefix.nbytes == 4);
}
static inline int insn_has_emulate_prefix(struct insn *insn)
{
return !!insn->emulate_prefix_size;
}
/* Ensure this instruction is decoded completely */
static inline int insn_complete(struct insn *insn)
{