On Mon, Nov 6, 2023 at 3:14 PM Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote: > > On Fri, Nov 3, 2023 at 11:49 AM Uros Bizjak <ubizjak@xxxxxxxxx> wrote: > > > > Instruction with %rip-relative address operand is one byte shorter than > > its absolute address counterpart and is also compatible with position > > independent executable (-fpie) build. > > > > No functional changes intended. > > I'm wondering what's the exact motivation for making this change. Mainly to be consistent with what the compiler emits by default when a symbol is accessed. As said in the commit message, the %rip-relative access is also one byte shorter, and results in a position independent code. > Any urgent need for it doesn't seem to be there. True. It's mostly a nice-to-have change. Thanks, Uros. > > Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx> > > Cc: Len Brown <len.brown@xxxxxxxxx> > > Cc: Pavel Machek <pavel@xxxxxx> > > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > > Cc: Ingo Molnar <mingo@xxxxxxxxxx> > > Cc: Borislav Petkov <bp@xxxxxxxxx> > > Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > > Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> > > Signed-off-by: Uros Bizjak <ubizjak@xxxxxxxxx> > > --- > > arch/x86/kernel/acpi/wakeup_64.S | 24 ++++++++++++------------ > > 1 file changed, 12 insertions(+), 12 deletions(-) > > > > diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S > > index d5d8a352eafa..94ff83f3d3fe 100644 > > --- a/arch/x86/kernel/acpi/wakeup_64.S > > +++ b/arch/x86/kernel/acpi/wakeup_64.S > > @@ -17,7 +17,7 @@ > > * Hooray, we are in Long 64-bit mode (but still running in low memory) > > */ > > SYM_FUNC_START(wakeup_long64) > > - movq saved_magic, %rax > > + movq saved_magic(%rip), %rax > > movq $0x123456789abcdef0, %rdx > > cmpq %rdx, %rax > > je 2f > > @@ -33,14 +33,14 @@ SYM_FUNC_START(wakeup_long64) > > movw %ax, %es > > movw %ax, %fs > > movw %ax, %gs > > - movq saved_rsp, %rsp > > + movq saved_rsp(%rip), %rsp > > > > - movq saved_rbx, %rbx > > - movq saved_rdi, %rdi > > - movq saved_rsi, %rsi > > - movq saved_rbp, %rbp > > + movq saved_rbx(%rip), %rbx > > + movq saved_rdi(%rip), %rdi > > + movq saved_rsi(%rip), %rsi > > + movq saved_rbp(%rip), %rbp > > > > - movq saved_rip, %rax > > + movq saved_rip(%rip), %rax > > ANNOTATE_RETPOLINE_SAFE > > jmp *%rax > > SYM_FUNC_END(wakeup_long64) > > @@ -72,11 +72,11 @@ SYM_FUNC_START(do_suspend_lowlevel) > > > > movq $.Lresume_point, saved_rip(%rip) > > > > - movq %rsp, saved_rsp > > - movq %rbp, saved_rbp > > - movq %rbx, saved_rbx > > - movq %rdi, saved_rdi > > - movq %rsi, saved_rsi > > + movq %rsp, saved_rsp(%rip) > > + movq %rbp, saved_rbp(%rip) > > + movq %rbx, saved_rbx(%rip) > > + movq %rdi, saved_rdi(%rip) > > + movq %rsi, saved_rsi(%rip) > > > > addq $8, %rsp > > movl $3, %edi > > --
