[xen staging] x86/ELF: eliminate pointless local variable from elf_core_save_regs()

[patchbot@xxxxxxx]

commit 7c6084c1f37dff3fcc4edbf080d16dec676f55fb
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Sep 29 10:53:13 2020 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Sep 29 10:53:13 2020 +0200

    x86/ELF: eliminate pointless local variable from elf_core_save_regs()
    
    We can just as well specify the CRn structure fields directly in the
    asm()s, just like done for all other ones.
    
    Also drop the unecessary "volatile" from the asm()-s: There are no
    relevant hidden side effects.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/include/asm-x86/x86_64/elf.h | 17 ++++-------------
 1 file changed, 4 insertions(+), 13 deletions(-)

diff --git a/xen/include/asm-x86/x86_64/elf.h b/xen/include/asm-x86/x86_64/elf.h
index f9c2789b7e..0d5fce515a 100644
--- a/xen/include/asm-x86/x86_64/elf.h
+++ b/xen/include/asm-x86/x86_64/elf.h
@@ -37,8 +37,6 @@ typedef struct {
 static inline void elf_core_save_regs(ELF_Gregset *core_regs, 
                                       crash_xen_core_t *xen_core_regs)
 {
-    unsigned long tmp;
-
     asm volatile("movq %%r15,%0" : "=m"(core_regs->r15));
     asm volatile("movq %%r14,%0" : "=m"(core_regs->r14));
     asm volatile("movq %%r13,%0" : "=m"(core_regs->r13));
@@ -67,17 +65,10 @@ static inline void elf_core_save_regs(ELF_Gregset 
*core_regs,
     core_regs->fs = read_sreg(fs);
     core_regs->gs = read_sreg(gs);
 
-    asm volatile("mov %%cr0, %0" : "=r" (tmp) : );
-    xen_core_regs->cr0 = tmp;
-
-    asm volatile("mov %%cr2, %0" : "=r" (tmp) : );
-    xen_core_regs->cr2 = tmp;
-
-    asm volatile("mov %%cr3, %0" : "=r" (tmp) : );
-    xen_core_regs->cr3 = tmp;
-
-    asm volatile("mov %%cr4, %0" : "=r" (tmp) : );
-    xen_core_regs->cr4 = tmp;
+    asm ( "mov %%cr0, %0" : "=r" (xen_core_regs->cr0) );
+    asm ( "mov %%cr2, %0" : "=r" (xen_core_regs->cr2) );
+    asm ( "mov %%cr3, %0" : "=r" (xen_core_regs->cr3) );
+    asm ( "mov %%cr4, %0" : "=r" (xen_core_regs->cr4) );
 }
 
 #endif /* __X86_64_ELF_H__ */
--
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