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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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34
tools/arch/x86/lib/insn.c
View File

@@ -13,6 +13,8 @@
#include "../include/asm/inat.h"
#include "../include/asm/insn.h"
#include "../include/asm/emulate_prefix.h"
/* Verify next sizeof(t) bytes can be on the same instruction */
#define validate_next(t, insn, n) \
((insn)->next_byte + sizeof(t) + n <= (insn)->end_kaddr)
@@ -58,6 +60,36 @@ void insn_init(struct insn *insn, const void *kaddr, int buf_len, int x86_64)
insn->addr_bytes = 4;
}
static const insn_byte_t xen_prefix[] = { __XEN_EMULATE_PREFIX };
static const insn_byte_t kvm_prefix[] = { __KVM_EMULATE_PREFIX };
static int __insn_get_emulate_prefix(struct insn *insn,
const insn_byte_t *prefix, size_t len)
{
size_t i;
for (i = 0; i < len; i++) {
if (peek_nbyte_next(insn_byte_t, insn, i) != prefix[i])
goto err_out;
}
insn->emulate_prefix_size = len;
insn->next_byte += len;
return 1;
err_out:
return 0;
}
static void insn_get_emulate_prefix(struct insn *insn)
{
if (__insn_get_emulate_prefix(insn, xen_prefix, sizeof(xen_prefix)))
return;
__insn_get_emulate_prefix(insn, kvm_prefix, sizeof(kvm_prefix));
}
/**
* insn_get_prefixes - scan x86 instruction prefix bytes
* @insn: &struct insn containing instruction
@@ -76,6 +108,8 @@ void insn_get_prefixes(struct insn *insn)
if (prefixes->got)
return;
insn_get_emulate_prefix(insn);
nb = 0;
lb = 0;
b = peek_next(insn_byte_t, insn);