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>
---
x86/emulator.c | 132 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 132 insertions(+)
diff --git a/x86/emulator.c b/x86/emulator.c
index 96576e5..4981bfb 100644
--- a/x86/emulator.c
+++ b/x86/emulator.c
@@ -11,6 +11,16 @@ 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;
+};
+static struct regs inregs, outregs;
+extern struct regs save;
+
void report(const char *name, int result)
{
++tests;
@@ -685,6 +695,128 @@ static void test_shld_shrd(u32 *mem)
report("shrd (cl)", *mem == ((0x12345678 >> 3) | (5u << 29)));
}
+extern u8 insn_start[], insn_end[];
+extern u8 insn_emulate_start[], insn_emulate_end[];
+
+static void mk_insn_page(uint8_t *insn_page, uint8_t *alt_insn_page,
+ uint8_t *alt_insn, int alt_insn_length)
+{
+ int i, emul_offset;
+ for (i=1; i<insn_emulate_end - insn_emulate_start; i++)
+ insn_emulate_start[i] = 0x90; // nop
+ for (i=0; i<insn_end - insn_start; i++)
+ insn_page[i] = insn_start[i];
+ emul_offset = insn_emulate_start - insn_start;
+ for (i=0; i<alt_insn_length; i++)
+ alt_insn_page[i+emul_offset] = alt_insn[i];
+
+ asm volatile(
+ ".pushsection .text.insn, \"ax\" \n\t"
+ "insn_start:\n\t"
+ "ret\n\t"
+
+ "push %%rax; push %%rbx\n\t"
+ "push %%rcx; push %%rdx\n\t"
+ "push %%rsi; push %%rdi\n\t"
+ "push %%rbp\n\t"
+ "push %%r8; push %%r9\n\t"
+ "push %%r10; push %%r11\n\t"
+ "push %%r12; push %%r13\n\t"
+ "push %%r14; push %%r15\n\t"
+ "pushf\n\t"
+
+ "push 136+%[save] \n\t"
+ "popf \n\t"
+ "mov 0+%[save], %%rax \n\t"
+ "mov 8+%[save], %%rbx \n\t"
+ "mov 16+%[save], %%rcx \n\t"
+ "mov 24+%[save], %%rdx \n\t"
+ "mov 32+%[save], %%rsi \n\t"
+ "mov 40+%[save], %%rdi \n\t"
+ "mov 56+%[save], %%rbp \n\t"
+ "mov 64+%[save], %%r8 \n\t"
+ "mov 72+%[save], %%r9 \n\t"
+ "mov 80+%[save], %%r10 \n\t"
+ "mov 88+%[save], %%r11 \n\t"
+ "mov 96+%[save], %%r12 \n\t"
+ "mov 104+%[save], %%r13 \n\t"
+ "mov 112+%[save], %%r14 \n\t"
+ "mov 120+%[save], %%r15 \n\t"
+
+ "insn_emulate_start:\n\t"
+ "in (%%dx),%%al\n\t"
+ ". = . + 31\n\t"
+ "insn_emulate_end:\n\t"
+
+ "pushf \n\t"
+ "pop 136+%[save] \n\t"
+ "mov %%rax, 0+%[save] \n\t"
+ "mov %%rbx, 8+%[save] \n\t"
+ "mov %%rcx, 16+%[save] \n\t"
+ "mov %%rdx, 24+%[save] \n\t"
+ "mov %%rsi, 32+%[save] \n\t"
+ "mov %%rdi, 40+%[save] \n\t"
+ "mov %%rbp, 56+%[save] \n\t"
+ "mov %%r8, 64+%[save]\n\t"
+ "mov %%r9, 72+%[save]\n\t"
+ "mov %%r10, 80+%[save]\n\t"
+ "mov %%r11, 88+%[save]\n\t"
+ "mov %%r12, 96+%[save]\n\t"
+ "mov %%r13, 104+%[save]\n\t"
+ "mov %%r14, 112+%[save]\n\t"
+ "mov %%r15, 120+%[save]\n\t"
+
+ "popf\n\t"
+ "pop %%r15; pop %%r14 \n\t"
+ "pop %%r13; pop %%r12 \n\t"
+ "pop %%r11; pop %%r10 \n\t"
+ "pop %%r9; pop %%r8 \n\t"
+ "pop %%rbp \n\t"
+ "pop %%rdi; pop %%rsi \n\t"
+ "pop %%rdx; pop %%rcx \n\t"
+ "pop %%rbx; pop %%rax \n\t"
+
+ "ret\n\t"
+
+ "save:\n\t"
+ ". = . + 256\n\t"
+ "insn_end:\n\t"
+ ".popsection\n\t"
+ : [save]"=m"(save)
+ : : "memory", "cc"
+ );
+}
+
+static void trap_emulator(uint64_t *mem, uint8_t *insn_page,
+ uint8_t *alt_insn_page, void *insn_ram,
+ uint8_t* alt_insn, int alt_insn_length, int reserve_stack)
+{
+ ulong *cr3 = (ulong *)read_cr3();
+ extern u8 insn_start[];
+ int save_offset = (u8 *)(&save) - insn_start;
+
+ memset(insn_page, 0x90, 4096);
+ memset(alt_insn_page, 0x90, 4096);
+
+ save = inregs;
+ mk_insn_page(insn_page, alt_insn_page,
+ alt_insn, alt_insn_length);
+
+ // 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 = *((struct regs *)(&alt_insn_page[save_offset]));
+}
+
static void advance_rip_by_3_and_note_exception(struct ex_regs *regs)
{
++exceptions;
--
1.7.9.5
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