[kvm-unit-tests PATCH v2 04/10] x86 UEFI: Convert x86 test cases to PIC

[Zixuan Wang <zxwang42@gmail.com>]

From: Zixuan Wang <zixuanwang@google.com>

UEFI loads EFI applications to dynamic runtime addresses, so it requires
all applications to be compiled as PIC (position independent code). PIC
does not allow the usage of compile time absolute address.

This commit converts multiple x86 test cases to PIC so they can compile
and run in UEFI:

- x86/cet.efi

- x86/emulator.c: x86/emulator.c depends on lib/x86/usermode.c. But
  usermode.c contains non-PIC inline assembly code. This commit converts
  lib/x86/usermode.c and x86/emulator.c to PIC, so x86/emulator.c can
  compile and run in UEFI.

- x86/vmware_backdoors.c: it depends on lib/x86/usermode.c and now works
  without modifications.

- x86/eventinj.c

- x86/smap.c

- x86/access.c: it runs fine without '-cpu max', which disables the
  SMEP-related tests. But with '-cpu max', it crashes in the middle, so
  it is left disabled in this commit.

- x86/umip.c: convert to PIC and fix a bug:

  In summary, in the following line, %[sp0] can be compiled as a
  %r8-based offset address:

  x86/umip.c:127
  "mov %%" R "sp, %[sp0]\n\t" /* kernel sp for exception handlers */

  %r8 is then modified in function calls without saving/restoring, thus
  making the following line using the wrong address.

  x86/umip.c:148
  "mov %[sp0], %%" R "sp\n\t"

  This register is selected by the compiler, it's not guaranteed to be
  %r8 so we cannot just push/pop %r8 before/after the function call. A
  simple fix is to save the %rsp to %rbx.  %rbx is a callee-saved
  register, so its value is not modified by function calls.

Signed-off-by: Zixuan Wang <zixuanwang@google.com>
---
 lib/x86/usermode.c  |  3 ++-
 x86/Makefile.common | 10 +++++-----
 x86/Makefile.x86_64 |  7 ++++---
 x86/access.c        |  9 +++++----
 x86/cet.c           |  8 +++++---
 x86/emulator.c      |  5 +++--
 x86/eventinj.c      |  8 ++++++++
 x86/smap.c          | 13 +++++++++----
 x86/umip.c          | 26 +++++++++++++++++++++++---
 9 files changed, 64 insertions(+), 25 deletions(-)

diff --git a/lib/x86/usermode.c b/lib/x86/usermode.c
index 2e77831..5b657fd 100644
--- a/lib/x86/usermode.c
+++ b/lib/x86/usermode.c
@@ -58,7 +58,8 @@ uint64_t run_in_user(usermode_func func, unsigned int fault_vector,
 			"pushq %[user_stack_top]\n\t"
 			"pushfq\n\t"
 			"pushq %[user_cs]\n\t"
-			"pushq $user_mode\n\t"
+			"lea user_mode(%%rip), %%rdx\n\t"
+			"pushq %%rdx\n\t"
 			"iretq\n"
 
 			"user_mode:\n\t"
diff --git a/x86/Makefile.common b/x86/Makefile.common
index deaa386..2b39dd5 100644
--- a/x86/Makefile.common
+++ b/x86/Makefile.common
@@ -81,16 +81,16 @@ tests-common = $(TEST_DIR)/vmexit.$(exe) $(TEST_DIR)/tsc.$(exe) \
                $(TEST_DIR)/init.$(exe) \
                $(TEST_DIR)/hyperv_synic.$(exe) $(TEST_DIR)/hyperv_stimer.$(exe) \
                $(TEST_DIR)/hyperv_connections.$(exe) \
-               $(TEST_DIR)/tsx-ctrl.$(exe)
+               $(TEST_DIR)/tsx-ctrl.$(exe) \
+               $(TEST_DIR)/eventinj.$(exe) \
+               $(TEST_DIR)/smap.$(exe) \
+               $(TEST_DIR)/umip.$(exe)
 
 # The following test cases are disabled when building EFI tests because they
 # use absolute addresses in their inline assembly code, which cannot compile
 # with the '-fPIC' flag
 ifneq ($(TARGET_EFI),y)
-tests-common += $(TEST_DIR)/eventinj.$(exe) \
-                $(TEST_DIR)/smap.$(exe) \
-                $(TEST_DIR)/realmode.$(exe) \
-                $(TEST_DIR)/umip.$(exe)
+tests-common += $(TEST_DIR)/realmode.$(exe)
 endif
 
 test_cases: $(tests-common) $(tests)
diff --git a/x86/Makefile.x86_64 b/x86/Makefile.x86_64
index fe6457c..3963840 100644
--- a/x86/Makefile.x86_64
+++ b/x86/Makefile.x86_64
@@ -30,6 +30,8 @@ tests += $(TEST_DIR)/intel-iommu.$(exe)
 tests += $(TEST_DIR)/rdpru.$(exe)
 tests += $(TEST_DIR)/pks.$(exe)
 tests += $(TEST_DIR)/pmu_lbr.$(exe)
+tests += $(TEST_DIR)/emulator.$(exe)
+tests += $(TEST_DIR)/vmware_backdoors.$(exe)
 
 ifeq ($(TARGET_EFI),y)
 tests += $(TEST_DIR)/amd_sev.$(exe)
@@ -40,14 +42,13 @@ endif
 # with the '-fPIC' flag
 ifneq ($(TARGET_EFI),y)
 tests += $(TEST_DIR)/access.$(exe)
-tests += $(TEST_DIR)/emulator.$(exe)
 tests += $(TEST_DIR)/svm.$(exe)
 tests += $(TEST_DIR)/vmx.$(exe)
-tests += $(TEST_DIR)/vmware_backdoors.$(exe)
+endif
+
 ifneq ($(fcf_protection_full),)
 tests += $(TEST_DIR)/cet.$(exe)
 endif
-endif
 
 include $(SRCDIR)/$(TEST_DIR)/Makefile.common
 
diff --git a/x86/access.c b/x86/access.c
index 911f0e3..a2ec049 100644
--- a/x86/access.c
+++ b/x86/access.c
@@ -700,7 +700,7 @@ static int ac_test_do_access(ac_test_t *at)
 
     if (F(AC_ACCESS_TWICE)) {
 	asm volatile (
-	    "mov $fixed2, %%rsi \n\t"
+	    "lea fixed2(%%rip), %%rsi \n\t"
 	    "mov (%[addr]), %[reg] \n\t"
 	    "fixed2:"
 	    : [reg]"=r"(r), [fault]"=a"(fault), "=b"(e)
@@ -710,7 +710,7 @@ static int ac_test_do_access(ac_test_t *at)
 	fault = 0;
     }
 
-    asm volatile ("mov $fixed1, %%rsi \n\t"
+    asm volatile ("lea fixed1(%%rip), %%rsi \n\t"
 		  "mov %%rsp, %[rsp0] \n\t"
 		  "cmp $0, %[user] \n\t"
 		  "jz do_access \n\t"
@@ -719,7 +719,8 @@ static int ac_test_do_access(ac_test_t *at)
 		  "pushq %[user_stack_top] \n\t"
 		  "pushfq \n\t"
 		  "pushq %[user_cs] \n\t"
-		  "pushq $do_access \n\t"
+		  "lea do_access(%%rip), %%r8\n\t"
+		  "pushq %%r8\n\t"
 		  "iretq \n"
 		  "do_access: \n\t"
 		  "cmp $0, %[fetch] \n\t"
@@ -750,7 +751,7 @@ static int ac_test_do_access(ac_test_t *at)
 		    [user_cs]"i"(USER_CS),
 		    [user_stack_top]"r"(user_stack + sizeof user_stack),
 		    [kernel_entry_vector]"i"(0x20)
-		  : "rsi");
+		  : "rsi", "r8");
 
     asm volatile (".section .text.pf \n\t"
 		  "page_fault: \n\t"
diff --git a/x86/cet.c b/x86/cet.c
index a21577a..a4b79cb 100644
--- a/x86/cet.c
+++ b/x86/cet.c
@@ -52,7 +52,7 @@ static u64 cet_ibt_func(void)
 	printf("No endbr64 instruction at jmp target, this triggers #CP...\n");
 	asm volatile ("movq $2, %rcx\n"
 		      "dec %rcx\n"
-		      "leaq 2f, %rax\n"
+		      "leaq 2f(%rip), %rax\n"
 		      "jmp *%rax \n"
 		      "2:\n"
 		      "dec %rcx\n");
@@ -67,7 +67,8 @@ void test_func(void) {
 			"pushq %[user_stack_top]\n\t"
 			"pushfq\n\t"
 			"pushq %[user_cs]\n\t"
-			"pushq $user_mode\n\t"
+			"lea user_mode(%%rip), %%rax\n\t"
+			"pushq %%rax\n\t"
 			"iretq\n"
 
 			"user_mode:\n\t"
@@ -77,7 +78,8 @@ void test_func(void) {
 			[user_ds]"i"(USER_DS),
 			[user_cs]"i"(USER_CS),
 			[user_stack_top]"r"(user_stack +
-					sizeof(user_stack)));
+					sizeof(user_stack))
+			: "rax");
 }
 
 #define SAVE_REGS() \
diff --git a/x86/emulator.c b/x86/emulator.c
index c5f584a..22a518f 100644
--- a/x86/emulator.c
+++ b/x86/emulator.c
@@ -262,12 +262,13 @@ static void test_pop(void *mem)
 
 	asm volatile("mov %%rsp, %[tmp] \n\t"
 		     "mov %[stack_top], %%rsp \n\t"
-		     "push $1f \n\t"
+		     "lea 1f(%%rip), %%rax \n\t"
+		     "push %%rax \n\t"
 		     "ret \n\t"
 		     "2: jmp 2b \n\t"
 		     "1: mov %[tmp], %%rsp"
 		     : [tmp]"=&r"(tmp) : [stack_top]"r"(stack_top)
-		     : "memory");
+		     : "memory", "rax");
 	report_pass("ret");
 
 	stack_top[-1] = 0x778899;
diff --git a/x86/eventinj.c b/x86/eventinj.c
index 46593c9..3c0db56 100644
--- a/x86/eventinj.c
+++ b/x86/eventinj.c
@@ -155,9 +155,17 @@ asm("do_iret:"
 	"pushf"W" \n\t"
 	"mov %cs, %ecx \n\t"
 	"push"W" %"R "cx \n\t"
+#ifndef __x86_64__
 	"push"W" $2f \n\t"
 
 	"cmpb $0, no_test_device\n\t"	// see if need to flush
+#else
+	"leaq 2f(%rip), %rbx \n\t"
+	"pushq %rbx \n\t"
+
+	"mov no_test_device(%rip), %bl \n\t"
+	"cmpb $0, %bl\n\t"		// see if need to flush
+#endif
 	"jnz 1f\n\t"
 	"outl %eax, $0xe4 \n\t"		// flush page
 	"1: \n\t"
diff --git a/x86/smap.c b/x86/smap.c
index c6ddf38..0994c29 100644
--- a/x86/smap.c
+++ b/x86/smap.c
@@ -159,12 +159,17 @@ int main(int ac, char **av)
 		init_test(i);
 		stac();
 		test = -1;
+#ifndef __x86_64__
+		#define TEST "test"
+#else
+		#define TEST "test(%rip)"
+#endif
 		asm("or $(" xstr(USER_BASE) "), %"R "sp \n"
 		    "push $44 \n "
-		    "decl test\n"
+		    "decl " TEST "\n"
 		    "and $~(" xstr(USER_BASE) "), %"R "sp \n"
 		    "pop %"R "ax\n"
-		    "movl %eax, test");
+		    "movl %eax, " TEST "\n");
 		report(pf_count == 0 && test == 44,
 		       "write to user stack with AC=1");
 
@@ -173,10 +178,10 @@ int main(int ac, char **av)
 		test = -1;
 		asm("or $(" xstr(USER_BASE) "), %"R "sp \n"
 		    "push $45 \n "
-		    "decl test\n"
+		    "decl " TEST "\n"
 		    "and $~(" xstr(USER_BASE) "), %"R "sp \n"
 		    "pop %"R "ax\n"
-		    "movl %eax, test");
+		    "movl %eax, " TEST "\n");
 		report(pf_count == 1 && test == 45 && save == -1,
 		       "write to user stack with AC=0");
 
diff --git a/x86/umip.c b/x86/umip.c
index af8db59..fccdedc 100644
--- a/x86/umip.c
+++ b/x86/umip.c
@@ -20,10 +20,20 @@ static void gp_handler(struct ex_regs *regs)
     }
 }
 
+#ifndef __x86_64__
+#define GP_ASM_MOVE_TO_RIP                  \
+	"mov" W " $1f, %[expected_rip]\n\t"
+#else
+#define GP_ASM_MOVE_TO_RIP                  \
+	"pushq %%rax\n\t"                   \
+	"lea 1f(%%rip), %%rax\n\t"          \
+	"mov %%rax, %[expected_rip]\n\t"    \
+	"popq %%rax\n\t"
+#endif
 
 #define GP_ASM(stmt, in, clobber)                  \
     asm volatile (                                 \
-          "mov" W " $1f, %[expected_rip]\n\t"      \
+	  GP_ASM_MOVE_TO_RIP                       \
           "movl $2f-1f, %[skip_count]\n\t"         \
           "1: " stmt "\n\t"                        \
           "2: "                                    \
@@ -125,12 +135,18 @@ static noinline int do_ring3(void (*fn)(const char *), const char *arg)
 		  "mov %%dx, %%fs\n\t"
 		  "mov %%dx, %%gs\n\t"
 		  "mov %%" R "sp, %[sp0]\n\t" /* kernel sp for exception handlers */
+		  "mov %[sp0], %%" R "bx\n\t" /* ebx/rbx is preserved before and after 'call' instruction */
 		  "push" W " %%" R "dx \n\t"
 		  "lea %[user_stack_top], %%" R "dx \n\t"
 		  "push" W " %%" R "dx \n\t"
 		  "pushf" W "\n\t"
 		  "push" W " %[user_cs] \n\t"
+#ifndef __x86_64__
 		  "push" W " $1f \n\t"
+#else
+		  "lea 1f(%%rip), %%rdx \n\t"
+		  "pushq %%rdx \n\t"
+#endif
 		  "iret" W "\n"
 		  "1: \n\t"
 #ifndef __x86_64__
@@ -140,12 +156,16 @@ static noinline int do_ring3(void (*fn)(const char *), const char *arg)
 #ifndef __x86_64__
 		  "pop %%ecx\n\t"
 #endif
+#ifndef __x86_64__
 		  "mov $1f, %%" R "dx\n\t"
+#else
+		  "lea 1f(%%" R "ip), %%" R "dx\n\t"
+#endif
 		  "int %[kernel_entry_vector]\n\t"
 		  ".section .text.entry \n\t"
 		  "kernel_entry: \n\t"
 #ifdef __x86_64__
-		  "mov %[sp0], %%" R "sp\n\t"
+		  "mov %%rbx, %%rsp\n\t"
 #else
 		  "add $(5 * " S "), %%esp\n\t"
 #endif
@@ -171,7 +191,7 @@ static noinline int do_ring3(void (*fn)(const char *), const char *arg)
 		    [arg]"D"(arg),
 		    [kernel_ds]"i"(KERNEL_DS),
 		    [kernel_entry_vector]"i"(0x20)
-		  : "rcx", "rdx");
+		  : "rcx", "rdx", "rbx");
     return ret;
 }
 
-- 
2.33.0