[xen staging] x86/ELF: don't store function pointer in elf_core_save_regs()

[patchbot@xxxxxxx]

commit 1e15dcfbaef6ef5b1cdba73408be6bd9dfc27fe9
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Sep 29 10:51:54 2020 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Sep 29 10:51:54 2020 +0200

    x86/ELF: don't store function pointer in elf_core_save_regs()
    
    This keeps at least gcc 10 from generating a separate function instance
    in common/kexec.o alongside the inlining of the function in its sole
    caller. I also think putting the address of the actual code storing the
    registers is a better indication to consumers than that of an otherwise
    unreferenced function.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/include/asm-x86/x86_64/elf.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/include/asm-x86/x86_64/elf.h b/xen/include/asm-x86/x86_64/elf.h
index 09b286422d..43c9cf3a3f 100644
--- a/xen/include/asm-x86/x86_64/elf.h
+++ b/xen/include/asm-x86/x86_64/elf.h
@@ -54,7 +54,7 @@ static inline void elf_core_save_regs(ELF_Gregset *core_regs,
     asm volatile("movq %%rsi,%0" : "=m"(core_regs->rsi));
     asm volatile("movq %%rdi,%0" : "=m"(core_regs->rdi));
     /* orig_rax not filled in for now */
-    core_regs->rip = (unsigned long)elf_core_save_regs;
+    asm ( "call 0f; 0: popq %0" : "=m" (core_regs->rip) );
     core_regs->cs = read_sreg(cs);
     asm volatile("pushfq; popq %0" :"=m"(core_regs->rflags));
     asm volatile("movq %%rsp,%0" : "=m"(core_regs->rsp));
--
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