fix(sev): do not use rbx register in asm!()

error: invalid register rbx: rbx is used internally by LLVM and
cannot be used as an operand for inline asm

See:
rust-lang/rust#84658 (comment)

and:
https://github.com/rust-lang/rust/pull/84658/files#diff-d7283132d97a993fad4e2d491ac883dbce4e17fe248cdf37fa3f9334e2a5a115

Signed-off-by: Harald Hoyer <harald@redhat.com>

helper/parse-trace.sh

@@ -42,7 +42,7 @@ while read line; do
     fi
 
     if [[ $ADDR2LINE = "REGS" ]]; then
-        if [[ $line = *"rflags:"* ]] || [[ $line = *"rsp:"* ]] || [[ $line = *"rbp:"* ]]; then
+        if [[ $line = *"rflags:"* ]] || [[ $line = *"rsp:"* ]] || [[ $line = *"rbp:"* ]] || [[ $line = *"rbx:"* ]]; then
             continue
         fi
     fi

internal/shim-sev/src/asm.rs

@@ -56,19 +56,18 @@ pub unsafe fn _enarx_asm_triple_fault() -> ! {
     // Provoke an #UD, which will lead to a triple fault, because of the invalid IDT
     asm!("ud2",
     in("rax") frames[2], // the first two frames are from panic
-    in("rbx") frames[3],
-    in("rcx") frames[4],
-    in("rdx") frames[5],
-    in("rsi") frames[6],
-    in("rdi") frames[7],
-    in("r8") frames[8],
-    in("r9") frames[9],
-    in("r10") frames[10],
-    in("r11") frames[11],
-    in("r12") frames[12],
-    in("r13") frames[13],
-    in("r14") frames[14],
-    in("r15") frames[15],
+    in("rcx") frames[3],
+    in("rdx") frames[4],
+    in("rsi") frames[5],
+    in("rdi") frames[6],
+    in("r8") frames[7],
+    in("r9") frames[8],
+    in("r10") frames[9],
+    in("r11") frames[10],
+    in("r12") frames[11],
+    in("r13") frames[12],
+    in("r14") frames[13],
+    in("r15") frames[14],
         options(nomem, nostack)
     );