Run the test with Intel's vendor ID and in the long mode,
to test the emulation of this instruction on AMD.
Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
---
x86/Makefile.x86_64 | 2 +
x86/sysenter.c | 127 ++++++++++++++++++++++++++++++++++++++++++++
x86/unittests.cfg | 5 ++
3 files changed, 134 insertions(+)
create mode 100644 x86/sysenter.c
diff --git a/x86/Makefile.x86_64 b/x86/Makefile.x86_64
index 865da07d..8ce53650 100644
--- a/x86/Makefile.x86_64
+++ b/x86/Makefile.x86_64
@@ -33,6 +33,7 @@ tests += $(TEST_DIR)/vmware_backdoors.$(exe)
tests += $(TEST_DIR)/rdpru.$(exe)
tests += $(TEST_DIR)/pks.$(exe)
tests += $(TEST_DIR)/pmu_lbr.$(exe)
+tests += $(TEST_DIR)/sysenter.$(exe)
ifeq ($(CONFIG_EFI),y)
@@ -60,3 +61,4 @@ $(TEST_DIR)/hyperv_clock.$(bin): $(TEST_DIR)/hyperv_clock.o
$(TEST_DIR)/vmx.$(bin): $(TEST_DIR)/vmx_tests.o
$(TEST_DIR)/svm.$(bin): $(TEST_DIR)/svm_tests.o
$(TEST_DIR)/svm_npt.$(bin): $(TEST_DIR)/svm_npt.o
+$(TEST_DIR)/sysenter.o: CFLAGS += -Wa,-mintel64
diff --git a/x86/sysenter.c b/x86/sysenter.c
new file mode 100644
index 00000000..6c32fea4
--- /dev/null
+++ b/x86/sysenter.c
@@ -0,0 +1,127 @@
+#include "alloc.h"
+#include "libcflat.h"
+#include "processor.h"
+#include "msr.h"
+#include "desc.h"
+
+
+// undefine this to run the syscall instruction in 64 bit mode.
+// this won't work on AMD due to disabled code in the emulator.
+#define COMP32
+
+int main(int ac, char **av)
+{
+ extern void sysenter_target(void);
+ extern void test_done(void);
+
+ setup_vm();
+
+ int gdt_index = 0x50 >> 3;
+ ulong rax = 0xDEAD;
+
+ /* init the sysenter GDT block */
+ /*gdt64[gdt_index+0] = gdt64[KERNEL_CS >> 3];
+ gdt64[gdt_index+1] = gdt64[KERNEL_DS >> 3];
+ gdt64[gdt_index+2] = gdt64[USER_CS >> 3];
+ gdt64[gdt_index+3] = gdt64[USER_DS >> 3];*/
+
+ /* init the sysenter msrs*/
+ wrmsr(MSR_IA32_SYSENTER_CS, gdt_index << 3);
+ wrmsr(MSR_IA32_SYSENTER_ESP, 0xAAFFFFFFFF);
+ wrmsr(MSR_IA32_SYSENTER_EIP, (uint64_t)sysenter_target);
+
+ u8 *thunk = (u8*)malloc(50);
+ u8 *tmp = thunk;
+
+ printf("Thunk at 0x%lx\n", (u64)thunk);
+
+ /* movabs test_done, %rdx*/
+ *tmp++ = 0x48; *tmp++ = 0xBA;
+ *(u64 *)tmp = (uint64_t)test_done; tmp += 8;
+ /* jmp %%rdx*/
+ *tmp++ = 0xFF; *tmp++ = 0xe2;
+
+ asm volatile (
+#ifdef COMP32
+ "# switch to comp32, mode prior to running the test\n"
+ "ljmpl *1f\n"
+ "1:\n"
+ ".long 1f\n"
+ ".long " xstr(KERNEL_CS32) "\n"
+ "1:\n"
+ ".code32\n"
+#else
+ "# store the 64 bit thunk address to rdx\n"
+ "mov %[thunk], %%rdx\n"
+#endif
+ "#+++++++++++++++++++++++++++++++++++++++++++++++++++"
+ "# user code (64 bit or comp32)"
+ "#+++++++++++++++++++++++++++++++++++++++++++++++++++"
+
+ "# use sysenter to enter 64 bit system code\n"
+ "mov %%esp, %%ecx #stash rsp value\n"
+ "mov $1, %%ebx\n"
+ "sysenter\n"
+ "ud2\n"
+
+ "#+++++++++++++++++++++++++++++++++++++++++++++++++++\n"
+ "# 64 bit cpl=0 code"
+ "#+++++++++++++++++++++++++++++++++++++++++++++++++++\n"
+
+ ".code64\n"
+ "sysenter_target:\n"
+
+#ifdef COMP32
+ "test %%rbx, %%rbx # check if we are here for second time \n"
+ "jne 1f\n"
+ "movq %%rcx, %%rsp # restore stack pointer manually\n"
+ "jmp test_done\n"
+ "1:\n"
+#endif
+
+ "# test that MSR_IA32_SYSENTER_ESP is correct\n"
+ "movq $0xAAFFFFFFFF, %%rbx\n"
+ "movq $0xDEAD, %%rax\n"
+ "cmpq %%rsp, %%rbx \n"
+ "jne 1f\n"
+ "movq $0xACED, %%rax\n"
+
+ "# use sysexit to exit back\n"
+ "1:\n"
+#ifdef COMP32
+ "leaq sysexit_target, %%rdx\n"
+ "sysexit\n"
+ "sysexit_target:\n"
+ "# second sysenter to return to CPL=0 and 64 bit\n"
+ "# the sysenter handler will jump back to here without sysexit due to ebx=0\n"
+ ".code32\n"
+ "mov $0, %%ebx\n"
+ "sysenter\n"
+#else
+ "# this will go through thunk to test_done, which tests,\n"
+ "# that we can sysexit to high addresses\n"
+ ".byte 0x48\n"
+ "sysexit\n"
+ "ud2\n"
+#endif
+
+ ".code64\n"
+ "test_done:\n"
+ "nop\n"
+
+ : /*outputs*/
+ "=a" (rax)
+ : /* inputs*/
+ [thunk] "r" (thunk)
+ : /*clobbers*/
+ "rbx", /* action flag for sysenter_target */
+ "rcx", /* saved RSP */
+ "rdx", /* used for SYSEXIT*/
+ "flags"
+ );
+
+ report(rax == 0xACED, "MSR_IA32_SYSENTER_ESP has correct value");
+ return report_summary();
+}
+
+
diff --git a/x86/unittests.cfg b/x86/unittests.cfg
index db9bb3ac..ebb3fdfc 100644
--- a/x86/unittests.cfg
+++ b/x86/unittests.cfg
@@ -223,6 +223,11 @@ file = syscall.flat
arch = x86_64
extra_params = -cpu Opteron_G1,vendor=AuthenticAMD
+[sysenter]
+file = sysenter.flat
+arch = x86_64
+extra_params = -cpu host,vendor=GenuineIntel
+
[tsc]
file = tsc.flat
extra_params = -cpu kvm64,+rdtscp
--
2.26.3
