On 8/3/22 20:16, Sean Christopherson wrote:
While here, I've also took the opportunity to merge both 32 and 64-bit
versions of ASM_TRY() (.dc.a for .long and .quad), but perhaps there
were some reasons for not using .dc.a?
This should be a separate patch, and probably as the very last patch in case dc.a
isn't viable for whatever reason. I've never seen/used dc.a so I really have no
idea whether or not it's ok to use.
Yes, for now I'll squash this, which is similar to Michal's idea but
using the trusty double underscore prefix:
diff --git a/lib/x86/desc.h b/lib/x86/desc.h
index 2a285eb..5b21820 100644
--- a/lib/x86/desc.h
+++ b/lib/x86/desc.h
@@ -81,11 +81,12 @@ typedef struct __attribute__((packed)) {
} tss64_t;
#ifdef __x86_64
-#define ASM_TRY(catch) \
+#define __ASM_TRY(prefix, catch) \
"movl $0, %%gs:4 \n\t" \
".pushsection .data.ex \n\t" \
".quad 1111f, " catch "\n\t" \
".popsection \n\t" \
+ prefix "\n\t" \
"1111:"
#else
#define ASM_TRY(catch) \
@@ -96,6 +97,8 @@ typedef struct __attribute__((packed)) {
"1111:"
#endif
+#define ASM_TRY(catch) __ASM_TRY("", catch)
+
/*
* selector 32-bit 64-bit
* 0x00 NULL descriptor NULL descriptor
diff --git a/x86/emulator.c b/x86/emulator.c
index df0bc49..6d2f166 100644
--- a/x86/emulator.c
+++ b/x86/emulator.c
@@ -19,6 +19,7 @@ static int exceptions;
/* Forced emulation prefix, used to invoke the emulator
unconditionally. */
#define KVM_FEP "ud2; .byte 'k', 'v', 'm';"
+#define ASM_TRY_FEP(catch) __ASM_TRY(KVM_FEP, catch)
struct regs {
u64 rax, rbx, rcx, rdx;
@@ -900,8 +901,8 @@ static void test_illegal_lea(void)
{
unsigned int vector;
- asm volatile (ASM_TRY("1f")
- KVM_FEP ".byte 0x8d; .byte 0xc0\n\t"
+ asm volatile (ASM_TRY_FEP("1f")
+ ".byte 0x8d; .byte 0xc0\n\t"
"1:"
: : : "memory", "eax");
and the __ASM_SEL() idea can be sent as a separate patch.
