[kvm-unit-tests PATCH v2 6/6] x86 UEFI: Convert x86 test cases to PIC

Varad Gautam
2021-08-19T11:35:20Z

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 and thus blocks the
compilation with GNU-EFI. 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@google.com>
---
lib/x86/usermode.c | 3 ++-
x86/Makefile.common | 7 ++++---
x86/Makefile.x86_64 | 5 +++--
x86/access.c | 6 +++---
x86/cet.c | 8 +++++---
x86/emulator.c | 5 +++--
x86/eventinj.c | 6 ++++--
x86/smap.c | 8 ++++----
x86/umip.c | 10 +++++++---
9 files changed, 35 insertions(+), 23 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 ca33e8e..a91fd4c 100644
--- a/x86/Makefile.common
+++ b/x86/Makefile.common
@@ -61,8 +61,8 @@ FLATLIBS = lib/libcflat.a
-j .reloc -j .init --target efi-app-x86_64 $*.so $@
@chmod a-x $@

-tests-flatonly = $(TEST_DIR)/realmode.$(out) $(TEST_DIR)/eventinj.$(out) \
- $(TEST_DIR)/smap.$(out) $(TEST_DIR)/umip.$(out)
+tests-flatonly = $(TEST_DIR)/realmode.$(out) \
+ $(TEST_DIR)/smap.$(out)

tests-common = $(TEST_DIR)/vmexit.$(out) $(TEST_DIR)/tsc.$(out) \
$(TEST_DIR)/smptest.$(out) $(TEST_DIR)/msr.$(out) \
@@ -72,7 +72,8 @@ tests-common = $(TEST_DIR)/vmexit.$(out) $(TEST_DIR)/tsc.$(out) \
$(TEST_DIR)/tsc_adjust.$(out) $(TEST_DIR)/asyncpf.$(out) \
$(TEST_DIR)/init.$(out) $(TEST_DIR)/hyperv_synic.$(out) \
$(TEST_DIR)/hyperv_stimer.$(out) $(TEST_DIR)/hyperv_connections.$(out) \
- $(TEST_DIR)/tsx-ctrl.$(out)
+ $(TEST_DIR)/tsx-ctrl.$(out) \
+ $(TEST_DIR)/eventinj.$(out) $(TEST_DIR)/umip.$(out)

ifneq ($(CONFIG_EFI),y)
tests-common += $(tests-flatonly)
diff --git a/x86/Makefile.x86_64 b/x86/Makefile.x86_64
index f6c7bd7..e8843aa 100644
--- a/x86/Makefile.x86_64
+++ b/x86/Makefile.x86_64
@@ -18,9 +18,8 @@ cflatobjs += lib/x86/intel-iommu.o
cflatobjs += lib/x86/usermode.o

# Tests that have relocation / PIC problems and need more attention for EFI.
-tests_flatonly = $(TEST_DIR)/access.$(out) $(TEST_DIR)/emulator.$(out) \
+tests_flatonly = $(TEST_DIR)/access.$(out) \
$(TEST_DIR)/svm.$(out) $(TEST_DIR)/vmx.$(out) \
- $(TEST_DIR)/vmware_backdoors.$(out)

tests = $(TEST_DIR)/apic.$(out) $(TEST_DIR)/idt_test.$(out) \
$(TEST_DIR)/xsave.$(out) $(TEST_DIR)/rmap_chain.$(out) \
@@ -33,6 +32,8 @@ tests += $(TEST_DIR)/intel-iommu.$(out)
tests += $(TEST_DIR)/rdpru.$(out)
tests += $(TEST_DIR)/pks.$(out)
tests += $(TEST_DIR)/pmu_lbr.$(out)
+tests += $(TEST_DIR)/emulator.$(out)
+tests += $(TEST_DIR)/vmware_backdoors.$(out)

ifneq ($(fcf_protection_full),)
tests_flatonly += $(TEST_DIR)/cet.$(out)
diff --git a/x86/access.c b/x86/access.c
index 4725bbd..d0c84ca 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 +719,7 @@ 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), %%rsi; pushq %%rsi; lea fixed1(%%rip), %%rsi\n\t"
"iretq \n"
"do_access: \n\t"
"cmp $0, %[fetch] \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"
--
2.30.2