On Wed, Jun 10, 2015 at 03:19:14PM +0200, Pavel Machek wrote: > Hi! > > > Fix the following asmvalidate warnings: > > > > asmvalidate: arch/x86/kernel/acpi/wakeup_64.o: wakeup_long64()+0x15: unsupported jump to outside of function > > asmvalidate: arch/x86/kernel/acpi/wakeup_64.o: wakeup_long64()+0x55: unsupported jump to outside of function > > asmvalidate: arch/x86/kernel/acpi/wakeup_64.o: wakeup_long64(): unsupported fallthrough at end of function > > asmvalidate: arch/x86/kernel/acpi/wakeup_64.o: do_suspend_lowlevel()+0x9a: unsupported jump to outside of function > > asmvalidate: arch/x86/kernel/acpi/wakeup_64.o: do_suspend_lowlevel()+0x116: unsupported jump to outside of function > > asmvalidate: arch/x86/kernel/acpi/wakeup_64.o: do_suspend_lowlevel(): unsupported fallthrough at end of function > > asmvalidate: arch/x86/kernel/acpi/wakeup_64.o: do_suspend_lowlevel(): missing FP_SAVE/RESTORE macros > > > > 1. wakeup_long64() isn't a function that can be called. It's actually > > redirected to via a return instruction in the entry code. It > > shouldn't be annotated as a callable function. Change ENDPROC -> > > PROC accordingly. > > But I see -> END. Oops! It should say -> END. > > 2. do_suspend_lowlevel() is a non-leaf callable function, so > > save/restore the frame pointer with FP_SAVE/RESTORE. > > It does not work with the frame pointer itself. Is FP_SAVE/RESTORE > still neccessary? Will you need FP_RESTORE to wakeup_long64, then? wakeup_long64 jumps to .Lresume_point, which does the FP_RESTORE. > > 3. Remove the unnecessary jump to .Lresume_point, as it just results in > > jumping to the next instruction (which is a nop because of the > > align). Otherwise asmvalidate gets confused by the jump. > > It also results in flushing the pipeline. Ok, I guess this one is unneccessary. > > > 4. Change the "jmp restore_processor_state" to a call instruction, > > because jumping outside the function's boundaries isn't allowed. Now > > restore_processor_state() will return back to do_suspend_lowlevel() > > instead of do_suspend_lowlevel()'s caller. > > > > 5. Remove superfluous rsp changes. > > Did you test the changes? Yes, I verified that it didn't break suspend/resume on my system. > Do you plan to make similar changes to wakeup_32.S? Currently, asmvalidate is x86_64 only, so I'm only fixing the 64-bit stuff right now. > > diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S > > index 8c35df4..7e442be 100644 > > --- a/arch/x86/kernel/acpi/wakeup_64.S > > +++ b/arch/x86/kernel/acpi/wakeup_64.S > > @@ -5,6 +5,7 @@ > > #include <asm/page_types.h> > > #include <asm/msr.h> > > #include <asm/asm-offsets.h> > > +#include <asm/func.h> > > > > # Copyright 2003 Pavel Machek <pavel@xxxxxxx>, distribute under GPLv2 > > > > @@ -33,13 +34,13 @@ ENTRY(wakeup_long64) > > > > movq saved_rip, %rax > > jmp *%rax > > -ENDPROC(wakeup_long64) > > +END(wakeup_long64) > > > > This should result in no binary code changes, so that's ok with me... > > > ENTRY(do_suspend_lowlevel) > > - subq $8, %rsp > > + FP_SAVE > > xorl %eax, %eax > > call save_processor_state > > > > Are you sure? Stuff like > movq $saved_context, %rax > movq %rsp, pt_regs_sp(%rax) > > follows. And you did not modify wakeup_long64, which now receives > different value in saved_rsp. Hm, I'm looking hard, but I still don't see a problem with that code. It's saving rsp to the saved_context struct. As I mentioned above, it's ok for the wakeup_long64 path to restore the same rsp value, since it jumps to .Lresume_point which has FP_RESTORE. > > @@ -108,8 +108,9 @@ ENTRY(do_suspend_lowlevel) > > movq pt_regs_r15(%rax), %r15 > > > > xorl %eax, %eax > > - addq $8, %rsp > > - jmp restore_processor_state > > + call restore_processor_state > > + FP_RESTORE > > + ret > > ENDPROC(do_suspend_lowlevel) > > Umm. I rather liked the direct jump. Why? -- Josh -- To unsubscribe from this list: send the line "unsubscribe live-patching" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
