On Thu, Jun 20, 2013 at 06:45:21PM +0800, Arthur Chunqi Li wrote:
> 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.
>
Looks good, some comment bellow.
> 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;
> +}
> +
memcpy addition should be in separate patch usually, but for unit test
it is no a big deal.
> 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"
alt_insn_page can be allocated by alloc_page().
> +);
> +
> +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
--
Gleb.
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