| Message ID | 8abe7016-1cd7-246e-24ef-92d92ff27ad3@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | x86: introduce read_sregs() and elf_core_save_regs() adjustments | expand |
On 28/09/2020 13:06, Jan Beulich wrote: > 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. Hmm - that's unfortunate. elf_core_save_regs is certainly a useful name to spot in a backtrace. > Signed-off-by: Jan Beulich <jbeulich@suse.com> > > --- 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(EL > 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 volatile("call 0f; 0: popq %0" : "=m" (core_regs->rip)); lea 0(%rip) will be faster to execute, and this is 64bit code specifically. Either way, Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com> > core_regs->cs = read_sreg(cs); > asm volatile("pushfq; popq %0" :"=m"(core_regs->rflags)); > asm volatile("movq %%rsp,%0" : "=m"(core_regs->rsp)); >
--- 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(EL 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 volatile("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));
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@suse.com>