Test access to %bpl via modr/m addressing mode. This case can test another bug
in the boot of RHEL5.9 64-bit.
Signed-off-by: Arthur Chunqi Li <yzt...@gmail.com>
---
x86/emulator.c | 41 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 41 insertions(+)
diff --git a/x86/emulator.c b/x86/emulator.c
index 96576e5..3563971 100644
--- a/x86/emulator.c
+++ b/x86/emulator.c
@@ -901,6 +901,45 @@ static void test_simplealu(u32 *mem)
report("test", *mem == 0x8400);
}
+static void test_bpl_modrm(uint64_t *mem, uint8_t *insn_page,
+ uint8_t *alt_insn_page, void *insn_ram)
+{
+ ulong *cr3 = (ulong *)read_cr3();
+ uint16_t cx = 0;
+
+ // Pad with RET instructions
+ memset(insn_page, 0xc3, 4096);
+ memset(alt_insn_page, 0xc3, 4096);
+ // Place a trapping instruction in the page to trigger a VMEXIT
+ insn_page[0] = 0x66; // mov $0x4321, %cx
+ insn_page[1] = 0xb9;
+ insn_page[2] = 0x21;
+ insn_page[3] = 0x43;
+ insn_page[4] = 0x89; // mov %eax, (%rax)
+ insn_page[5] = 0x00;
+ insn_page[6] = 0x90; // nop
+ // Place mov %cl, %bpl in alt_insn_page for emulator to execuate
+ // If emulator mistaken addressing %bpl, %cl may be moved to %ch
+ // %cx will be broken to 0x2121, not 0x4321
+ alt_insn_page[4] = 0x40;
+ alt_insn_page[5] = 0x88;
+ alt_insn_page[6] = 0xcd;
+
+ // 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);
+ // Load code TLB
+ invlpg(insn_ram);
+ asm volatile("call *%0" : : "r"(insn_ram+3));
+ // Trap, let hypervisor emulate at alt_insn_page
+ install_page(cr3, virt_to_phys(alt_insn_page), insn_ram);
+ asm volatile("call *%0" : : "r"(insn_ram), "a"(mem));
+ asm volatile("":"=c"(cx));
+ report("access bpl in modr/m", cx == 0x4321);
+}
+
int main()
{
void *mem;
@@ -964,6 +1003,8 @@ int main()
test_string_io_mmio(mem);
+ test_bpl_modrm(mem, insn_page, alt_insn_page, insn_ram);
+
printf("\nSUMMARY: %d tests, %d failures\n", tests, fails);
return fails ? 1 : 0;
}
--
1.7.9.5
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
