[kvm-unit-tests PATCH 3/7] x86: realmode: syscall: add explicit size suffix to ambiguous instructions

morbo
2020-02-26T07:45:00Z

From: Bill Wendling <morbo@google.com>

Clang requires explicit size suffixes for potentially ambiguous
instructions:

x86/realmode.c:1647:2: error: ambiguous instructions require an explicit suffix (could be 'cmpb', 'cmpw', or 'cmpl')
MK_INSN_PERF(perf_memory_load, "cmp $0, (%edi)");
^
x86/realmode.c:1591:10: note: expanded from macro 'MK_INSN_PERF'
"1:" insn "\n" \
^
<inline asm>:8:3: note: instantiated into assembly here
1:cmp $0, (%edi)
^

The 'w' and 'l' suffixes generate code that's identical to the gcc
version without them.

Signed-off-by: Bill Wendling <morbo@google.com>
---
x86/realmode.c | 6 +++---
x86/syscall.c | 2 +-
2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/x86/realmode.c b/x86/realmode.c
index f5967ef..31f84d0 100644
--- a/x86/realmode.c
+++ b/x86/realmode.c
@@ -1644,7 +1644,7 @@ static void test_perf_memory_load(void)
{
u32 cyc, tmp;

- MK_INSN_PERF(perf_memory_load, "cmp $0, (%edi)");
+ MK_INSN_PERF(perf_memory_load, "cmpw $0, (%edi)");

init_inregs(&(struct regs){ .edi = (u32)&tmp });

@@ -1657,7 +1657,7 @@ static void test_perf_memory_store(void)
{
u32 cyc, tmp;

- MK_INSN_PERF(perf_memory_store, "mov %ax, (%edi)");
+ MK_INSN_PERF(perf_memory_store, "movw %ax, (%edi)");

init_inregs(&(struct regs){ .edi = (u32)&tmp });

@@ -1670,7 +1670,7 @@ static void test_perf_memory_rmw(void)
{
u32 cyc, tmp;

- MK_INSN_PERF(perf_memory_rmw, "add $1, (%edi)");
+ MK_INSN_PERF(perf_memory_rmw, "addw $1, (%edi)");

init_inregs(&(struct regs){ .edi = (u32)&tmp });

diff --git a/x86/syscall.c b/x86/syscall.c
index b4f5ac0..b7e29d6 100644
--- a/x86/syscall.c
+++ b/x86/syscall.c
@@ -38,7 +38,7 @@ static void handle_db(struct ex_regs *regs)

/* expects desired ring 3 flags in rax */
asm("syscall32_target:\n"
- " cmp $0, code_segment_upon_db(%rip)\n"
+ " cmpl $0, code_segment_upon_db(%rip)\n"
" jne back_to_test\n"
" mov %eax,%r11d\n"
" sysretl\n");
--
2.25.0.265.gbab2e86ba0-goog