Re: [kvm-unit-tests PATCH v3 11/17] x86 UEFI: Convert x86 test cases to PIC

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On 04/10/21 22:49, Zixuan Wang wrote:
From: Zixuan Wang <zixuanwang@xxxxxxxxxx>

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

- x86/umip.c

Signed-off-by: Zixuan Wang <zixuanwang@xxxxxxxxxx>
---
  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      |  6 ++++--
  x86/smap.c          |  8 ++++----
  x86/umip.c          | 10 +++++++---
  9 files changed, 39 insertions(+), 27 deletions(-)

diff --git a/lib/x86/usermode.c b/lib/x86/usermode.c
index f032523..c550545 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 4859bf3..959379c 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) \
+               $(TEST_DIR)/umip.$(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 += $(TEST_DIR)/smap.$(exe) \
+                $(TEST_DIR)/realmode.$(exe)
  endif
test_cases: $(tests-common) $(tests)
diff --git a/x86/Makefile.x86_64 b/x86/Makefile.x86_64
index aa23b22..7e8a57a 100644
--- a/x86/Makefile.x86_64
+++ b/x86/Makefile.x86_64
@@ -30,20 +30,21 @@ 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)
# 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 += $(TEST_DIR)/access.$(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 4725bbd..8d620a7 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, %%rdx \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"
@@ -744,7 +745,7 @@ 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 9fda1a0..4d2de24 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(1, "ret");
stack_top[-1] = 0x778899;
diff --git a/x86/eventinj.c b/x86/eventinj.c
index 46593c9..0cd68e8 100644
--- a/x86/eventinj.c
+++ b/x86/eventinj.c
@@ -155,9 +155,11 @@ asm("do_iret:"
  	"pushf"W" \n\t"
  	"mov %cs, %ecx \n\t"
  	"push"W" %"R "cx \n\t"
-	"push"W" $2f \n\t"
+	"lea"W" 2f(%"R "ip), %"R "bx \n\t"
+	"push"W" %"R "bx \n\t"
- "cmpb $0, no_test_device\n\t" // see if need to flush
+	"mov no_test_device(%"R "ip), %bl \n\t"
+	"cmpb $0, %bl\n\t"		// see if need to flush
  	"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 ac2c8d5..b3ee16f 100644
--- a/x86/smap.c
+++ b/x86/smap.c
@@ -161,10 +161,10 @@ int main(int ac, char **av)
  		test = -1;
  		asm("or $(" xstr(USER_BASE) "), %"R "sp \n"
  		    "push $44 \n "
-		    "decl test\n"
+		    "decl test(%"R "ip)\n"
  		    "and $~(" xstr(USER_BASE) "), %"R "sp \n"
  		    "pop %"R "ax\n"
-		    "movl %eax, test");
+		    "movl %eax, test(%"R "ip)");
  		report(pf_count == 0 && test == 44,
  		       "write to user stack with AC=1");
@@ -173,10 +173,10 @@ int main(int ac, char **av)
  		test = -1;
  		asm("or $(" xstr(USER_BASE) "), %"R "sp \n"
  		    "push $45 \n "
-		    "decl test\n"
+		    "decl test(%"R "ip)\n"
  		    "and $~(" xstr(USER_BASE) "), %"R "sp \n"
  		    "pop %"R "ax\n"
-		    "movl %eax, test");
+		    "movl %eax, test(%"R "ip)");
  		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 c5700b3..8b4e798 100644
--- a/x86/umip.c
+++ b/x86/umip.c
@@ -23,7 +23,10 @@ static void gp_handler(struct ex_regs *regs)
#define GP_ASM(stmt, in, clobber) \
      asm volatile (                                 \
-          "mov" W " $1f, %[expected_rip]\n\t"      \
+          "push" W " %%" R "ax\n\t"                \
+	  "lea 1f(%%" R "ip), %%" R "ax\n\t"       \
+          "mov %%" R "ax, %[expected_rip]\n\t"     \
+          "pop" W " %%" R "ax\n\t"                 \
            "movl $2f-1f, %[skip_count]\n\t"         \
            "1: " stmt "\n\t"                        \
            "2: "                                    \
@@ -130,7 +133,8 @@ static int do_ring3(void (*fn)(const char *), const char *arg)
  		  "push" W " %%" R "dx \n\t"
  		  "pushf" W "\n\t"
  		  "push" W " %[user_cs] \n\t"
-		  "push" W " $1f \n\t"
+		  "lea 1f(%%" R "ip), %%" R "dx \n\t"
+		  "push" W " %%" R "dx \n\t"
  		  "iret" W "\n"
  		  "1: \n\t"
  		  "push %%" R "cx\n\t"   /* save kernel SP */
@@ -144,7 +148,7 @@ static int do_ring3(void (*fn)(const char *), const char *arg)
  #endif
"pop %%" R "cx\n\t"
-		  "mov $1f, %%" R "dx\n\t"
+		  "lea 1f(%%" R "ip), %%" R "dx\n\t"
  		  "int %[kernel_entry_vector]\n\t"
  		  ".section .text.entry \n\t"
  		  "kernel_entry: \n\t"


I have left this patch out for now, because it breaks 32-bit builds. It's not a huge deal and can be redone on top of the rest.

Paolo




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