[Xen-changelog] [xen staging] x86: remove alternative_callN usage of ALTERNATIVE asm macro

[patchbot@xxxxxxx]

commit 2223d346648eb4045bd1497352b2ee8a3b1ec36a
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Mon Jun 3 17:55:37 2019 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Jun 3 17:55:37 2019 +0200

    x86: remove alternative_callN usage of ALTERNATIVE asm macro
    
    There is a bug in llvm that needs to be fixed before switching to use
    the alternative assembly macros in inline assembly call sites.
    Therefore alternative_callN using inline assembly to generate the
    alternative patch sites should be using the ALTERNATIVE C preprocessor
    macro rather than the ALTERNATIVE assembly macro. Using the assembly
    macro in an inline assembly instance triggers the following bug on
    llvm based toolchains:
    
    <instantiation>:1:1: error: invalid symbol redefinition
    .L0_orig_s: call *genapic+64(%rip); .L0_orig_e: .L0_diff = (.L0_repl_e1 - 
.L0_repl_s1) - (...
    ^
    <instantiation>:1:37: error: invalid symbol redefinition
    .L0_orig_s: call *genapic+64(%rip); .L0_orig_e: .L0_diff = (.L0_repl_e1 - 
.L0_repl_s1) - (...
                                        ^
    <instantiation>:1:60: error: invalid reassignment of non-absolute variable 
'.L0_diff'
    .L0_orig_s: call *genapic+64(%rip); .L0_orig_e: .L0_diff = (.L0_repl_e1 - 
.L0_repl_s1) - (...
                                                               ^
    <inline asm>:1:2: note: while in macro instantiation
            ALTERNATIVE "call *genapic+64(%rip)", "call .", X86_FEATURE_LM
            ^
    <instantiation>:1:156: error: invalid symbol redefinition
      ...- (.L0_orig_e - .L0_orig_s); mknops ((-(.L0_diff > 0)) * .L0_diff); 
.L0_orig_p:
                                                                             ^
    <instantiation>:18:5: error: invalid symbol redefinition
        .L0_repl_s1: call .; .L0_repl_e1:
        ^
    <instantiation>:18:26: error: invalid symbol redefinition
        .L0_repl_s1: call .; .L0_repl_e1:
                             ^
    <instantiation>:1:1: error: invalid symbol redefinition
    .L0_orig_s: call *genapic+64(%rip); .L0_orig_e: .L0_diff = (.L0_repl_e1 - 
.L0_repl_s1) - (...
    ^
    <instantiation>:1:37: error: invalid symbol redefinition
    .L0_orig_s: call *genapic+64(%rip); .L0_orig_e: .L0_diff = (.L0_repl_e1 - 
.L0_repl_s1) - (...
                                        ^
    <instantiation>:1:60: error: invalid reassignment of non-absolute variable 
'.L0_diff'
    .L0_orig_s: call *genapic+64(%rip); .L0_orig_e: .L0_diff = (.L0_repl_e1 - 
.L0_repl_s1) - (...
                                                               ^
    <inline asm>:1:2: note: while in macro instantiation
            ALTERNATIVE "call *genapic+64(%rip)", "call .", X86_FEATURE_LM
            ^
    <instantiation>:1:156: error: invalid symbol redefinition
      ...- (.L0_orig_e - .L0_orig_s); mknops ((-(.L0_diff > 0)) * .L0_diff); 
.L0_orig_p:
                                                                             ^
    <instantiation>:18:5: error: invalid symbol redefinition
        .L0_repl_s1: call .; .L0_repl_e1:
        ^
    <instantiation>:18:26: error: invalid symbol redefinition
        .L0_repl_s1: call .; .L0_repl_e1:
                             ^
    <instantiation>:1:1: error: invalid symbol redefinition
    .L0_orig_s: call *genapic+64(%rip); .L0_orig_e: .L0_diff = (.L0_repl_e1 - 
.L0_repl_s1) - (...
    ^
    <instantiation>:1:37: error: invalid symbol redefinition
    .L0_orig_s: call *genapic+64(%rip); .L0_orig_e: .L0_diff = (.L0_repl_e1 - 
.L0_repl_s1) - (...
                                        ^
    <instantiation>:1:60: error: invalid reassignment of non-absolute variable 
'.L0_diff'
    .L0_orig_s: call *genapic+64(%rip); .L0_orig_e: .L0_diff = (.L0_repl_e1 - 
.L0_repl_s1) - (...
                                                               ^
    <inline asm>:1:2: note: while in macro instantiation
            ALTERNATIVE "call *genapic+64(%rip)", "call .", X86_FEATURE_LM
            ^
    <instantiation>:1:156: error: invalid symbol redefinition
      ...- (.L0_orig_e - .L0_orig_s); mknops ((-(.L0_diff > 0)) * .L0_diff); 
.L0_orig_p:
                                                                             ^
    <instantiation>:18:5: error: invalid symbol redefinition
        .L0_repl_s1: call .; .L0_repl_e1:
        ^
    <instantiation>:18:26: error: invalid symbol redefinition
        .L0_repl_s1: call .; .L0_repl_e1:
                             ^
    
    This has been reported to upstream llvm:
    
    https://bugs.llvm.org/show_bug.cgi?id=42034
    
    Fixes: 67d01cdb5 ("x86: infrastructure to allow converting certain indirect 
calls to direct ones")
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/include/asm-x86/alternative.h | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/xen/include/asm-x86/alternative.h 
b/xen/include/asm-x86/alternative.h
index 63d0a450ba..92e3581bc2 100644
--- a/xen/include/asm-x86/alternative.h
+++ b/xen/include/asm-x86/alternative.h
@@ -202,9 +202,8 @@ extern void alternative_branches(void);
     rettype ret_;                                                  \
     register unsigned long r10_ asm("r10");                        \
     register unsigned long r11_ asm("r11");                        \
-    asm volatile (__stringify(ALTERNATIVE "call *%c[addr](%%rip)", \
-                                          "call .",                \
-                                          X86_FEATURE_ALWAYS)      \
+    asm volatile (ALTERNATIVE("call *%c[addr](%%rip)", "call .",   \
+                              X86_FEATURE_ALWAYS)                  \
                   : ALT_CALL ## n ## _OUT, "=a" (ret_),            \
                     "=r" (r10_), "=r" (r11_) ASM_CALL_CONSTRAINT   \
                   : [addr] "i" (&(func)), "g" (func)               \
--
generated by git-patchbot for /home/xen/git/xen.git#staging

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