Add a function trap_emulator to run an instruction in emulator.
Set inregs first (%rax is invalid because it is used as return
address), put instruction codec in alt_insn and call func with
alt_insn_length. Get results in outregs.
Signed-off-by: Arthur Chunqi Li <yzt356@xxxxxxxxx>
---
lib/libcflat.h | 1 +
lib/string.c | 12 +++++++++
x86/emulator.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 91 insertions(+)
diff --git a/lib/libcflat.h b/lib/libcflat.h
index 0875bd9..fadc33d 100644
--- a/lib/libcflat.h
+++ b/lib/libcflat.h
@@ -50,6 +50,7 @@ extern int vsnprintf(char *buf, int size, const char *fmt, va_list va);
extern void puts(const char *s);
extern void *memset(void *s, int c, size_t n);
+extern void *memcpy(void *dest, const void *src, size_t n);
extern long atol(const char *ptr);
#define ARRAY_SIZE(_a) (sizeof(_a)/sizeof((_a)[0]))
diff --git a/lib/string.c b/lib/string.c
index 9dc94a1..e798f86 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -42,6 +42,18 @@ void *memset(void *s, int c, size_t n)
return s;
}
+void *memcpy(void *dest, const void *src, size_t n)
+{
+ size_t i;
+ char *a = dest;
+ char *b = src;
+
+ for (i = 0; i < n; ++i)
+ a[i] = b[i];
+
+ return dest;
+}
+
long atol(const char *ptr)
{
long acc = 0;
diff --git a/x86/emulator.c b/x86/emulator.c
index 96576e5..b3626fa 100644
--- a/x86/emulator.c
+++ b/x86/emulator.c
@@ -11,6 +11,15 @@ int fails, tests;
static int exceptions;
+struct regs {
+ u64 rax, rbx, rcx, rdx;
+ u64 rsi, rdi, rsp, rbp;
+ u64 r8, r9, r10, r11;
+ u64 r12, r13, r14, r15;
+ u64 rip, rflags;
+};
+struct regs inregs, outregs, save;
+
void report(const char *name, int result)
{
++tests;
@@ -685,6 +694,75 @@ static void test_shld_shrd(u32 *mem)
report("shrd (cl)", *mem == ((0x12345678 >> 3) | (5u << 29)));
}
+#define INSN_XCHG_ALL \
+ "xchg %rax, 0+save \n\t" \
+ "xchg %rbx, 8+save \n\t" \
+ "xchg %rcx, 16+save \n\t" \
+ "xchg %rdx, 24+save \n\t" \
+ "xchg %rsi, 32+save \n\t" \
+ "xchg %rdi, 40+save \n\t" \
+ "xchg %rsp, 48+save \n\t" \
+ "xchg %rbp, 56+save \n\t" \
+ "xchg %r8, 64+save \n\t" \
+ "xchg %r9, 72+save \n\t" \
+ "xchg %r10, 80+save \n\t" \
+ "xchg %r11, 88+save \n\t" \
+ "xchg %r12, 96+save \n\t" \
+ "xchg %r13, 104+save \n\t" \
+ "xchg %r14, 112+save \n\t" \
+ "xchg %r15, 120+save \n\t" \
+
+asm(
+ ".align 4096\n\t"
+ "insn_page:\n\t"
+ "ret\n\t"
+ "pushf\n\t"
+ "push 136+save \n\t"
+ "popf \n\t"
+ INSN_XCHG_ALL
+ "test_insn:\n\t"
+ "in (%dx),%al\n\t"
+ ".skip 31, 0x90\n\t"
+ "test_insn_end:\n\t"
+ INSN_XCHG_ALL
+ "pushf \n\t"
+ "pop 136+save \n\t"
+ "popf \n\t"
+ "ret \n\t"
+ "insn_page_end:\n\t"
+ ".align 4096\n\t"
+
+ "alt_insn_page:\n\t"
+ ". = . + 4096\n\t"
+ ".align 4096\n\t"
+);
+
+static void trap_emulator(uint64_t *mem, uint8_t* alt_insn, int alt_insn_length)
+{
+ ulong *cr3 = (ulong *)read_cr3();
+ void *insn_ram;
+ extern u8 insn_page[], test_insn[], alt_insn_page[];
+
+ insn_ram = vmap(virt_to_phys(insn_page), 4096);
+ memcpy(alt_insn_page, test_insn, 4096);
+ memcpy(alt_insn_page + (test_insn - insn_page), alt_insn, alt_insn_length);
+ save = inregs;
+
+ /* Load the code TLB with insn_page, but point the page tables at
+ alt_insn_page (and keep the data TLB clear, for AMD decode assist).
+ This will make the CPU trap on the insn_page instruction but the
+ hypervisor will see alt_insn_page. */
+ install_page(cr3, virt_to_phys(insn_page), insn_ram);
+ invlpg(insn_ram);
+ /* Load code TLB */
+ asm volatile("call *%0" : : "r"(insn_ram));
+ install_page(cr3, virt_to_phys(alt_insn_page), insn_ram);
+ /* Trap, let hypervisor emulate at alt_insn_page */
+ asm volatile("call *%0": : "r"(insn_ram+1));
+
+ outregs = save;
+}
+
static void advance_rip_by_3_and_note_exception(struct ex_regs *regs)
{
++exceptions;
--
1.7.9.5
--
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