[Xen-devel] [PATCH v2 2/6] xen/x86: Replace unqualified ud2 instructions with BUG frames

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

No functional change, other than the failure cases, which now produce a
far more clear error message.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Jun Nakajima <jun.nakajima@xxxxxxxxx>
CC: Kevin Tian <kevin.tian@xxxxxxxxx>
---
 xen/arch/x86/boot/x86_64.S      | 2 +-
 xen/arch/x86/hvm/vmx/entry.S    | 2 +-
 xen/arch/x86/x86_64/entry.S     | 4 ++--
 xen/include/asm-x86/asm_defns.h | 2 +-
 4 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/boot/x86_64.S b/xen/arch/x86/boot/x86_64.S
index c8bf9d0..94cf089 100644
--- a/xen/arch/x86/boot/x86_64.S
+++ b/xen/arch/x86/boot/x86_64.S
@@ -34,7 +34,7 @@ ENTRY(__high_start)
         /* Pass off the Multiboot info structure to C land. */
         mov     multiboot_ptr(%rip),%edi
         call    __start_xen
-        ud2     /* Force a panic (invalid opcode). */
+        BUG     /* __start_xen() shouldn't return. */
 
 /*** DESCRIPTOR TABLES ***/
 
diff --git a/xen/arch/x86/hvm/vmx/entry.S b/xen/arch/x86/hvm/vmx/entry.S
index a5438a4..5a1757e 100644
--- a/xen/arch/x86/hvm/vmx/entry.S
+++ b/xen/arch/x86/hvm/vmx/entry.S
@@ -110,7 +110,7 @@ UNLIKELY_END(realmode)
         sti
         SAVE_ALL
         call vmx_vmentry_failure
-        ud2
+        BUG  /* vmx_vmentry_failure() shouldn't return. */
 
 ENTRY(vmx_asm_do_vmentry)
         GET_CURRENT(%rbx)
diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
index 28c3214..d4dd8e8 100644
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -547,7 +547,7 @@ exception_with_ints_disabled:
 FATAL_exception_with_ints_disabled:
         movq  %rsp,%rdi
         call  fatal_trap
-        ud2
+        BUG   /* fatal_trap() shouldn't return. */
 
 ENTRY(divide_error)
         pushq $0
@@ -620,7 +620,7 @@ ENTRY(double_fault)
         SAVE_ALL STAC
         movq  %rsp,%rdi
         call  do_double_fault
-        ud2
+        BUG   /* do_double_fault() shouldn't return. */
 
         .pushsection .init.text, "ax", @progbits
 ENTRY(early_page_fault)
diff --git a/xen/include/asm-x86/asm_defns.h b/xen/include/asm-x86/asm_defns.h
index d750f03..95ea21d 100644
--- a/xen/include/asm-x86/asm_defns.h
+++ b/xen/include/asm-x86/asm_defns.h
@@ -324,7 +324,7 @@ static always_inline void stac(void)
         jne   789f
         cmpq  UREGS_r12(%rsp),%r12
         je    987f
-789:    ud2
+789:    BUG   /* Corruption of partial register state. */
         .subsection 0
 #endif
 .endif
-- 
2.1.4


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