From: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Tue, 3 Oct 2023 10:05:22 +0000 (+0100)
Subject: Work around Clang IAS error with XSA-304
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=f0dd2fbc094598c625e96748f6ac64acec8fc725;p=people%2Fandrewcoop%2Fxen-test-framework.git

Work around Clang IAS error with XSA-304

Clang complains:

  <inline asm>:1:19: error: expected assembly-time absolute expression
  .align 4096;.skip 4096 - (stub_page_boundary - stub_fn);
                    ^

Opencode the je

Links: https://github.com/llvm/llvm-project/issues/68086
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---

diff --git a/tests/xsa-304/main.c b/tests/xsa-304/main.c
index 7f8be08..5d343e9 100644
--- a/tests/xsa-304/main.c
+++ b/tests/xsa-304/main.c
@@ -46,9 +46,12 @@ asm (".align 4096;"
      /*
       * %rsi points at `bool cond = true` on the stack, so this jump won't
       * actually be taken, but we want speculation to follow it.
+      *
+      * Work around https://github.com/llvm/llvm-project/issues/68086
+      * Clang IAS can't cope with `je 1f` so opencode it.
       */
      "    cmpb    $0, (%rsi);"
-     "    je      1f;"
+     "    .byte 0x74, 1f - (. + 1);" // je 1f
 
      /*
       * Write into the top of linear address space.  Because no A/D bits are