| Message ID | 2817f5690aa760a601a614b738545fd60b087bbb.1433937132.git.jpoimboe@redhat.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
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. > 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? > 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? Do you plan to make similar changes to wakeup_32.S? > 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@suse.cz>, 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. > @@ -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. Pavel
On Wed 2015-06-10 07:06:15, Josh Poimboeuf wrote: > 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 > Actually first things first. Purpose of warnings is to pinpoint errors. Do you believe there are some errors in wakeup_64.S? Pavel
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@suse.cz>, 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?
On Wed, Jun 10, 2015 at 03:21:35PM +0200, Pavel Machek wrote: > On Wed 2015-06-10 07:06:15, Josh Poimboeuf wrote: > > 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 > > > > Actually first things first. Purpose of warnings is to pinpoint > errors. Do you believe there are some errors in wakeup_64.S? The "errors" are that it doesn't conform with the guidelines outlined in the cover letter. Specifically, wakeup_long64() is improperly annotated, and do_suspend_lowlevel() doesn't honor CONFIG_FRAME_POINTER.
* Josh Poimboeuf <jpoimboe@redhat.com> wrote: > On Wed, Jun 10, 2015 at 03:21:35PM +0200, Pavel Machek wrote: > > On Wed 2015-06-10 07:06:15, Josh Poimboeuf wrote: > > > 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 > > > > > > > Actually first things first. Purpose of warnings is to pinpoint > > errors. Do you believe there are some errors in wakeup_64.S? > > The "errors" are that it doesn't conform with the guidelines outlined in > the cover letter. Specifically, wakeup_long64() is improperly > annotated, and do_suspend_lowlevel() doesn't honor CONFIG_FRAME_POINTER. Please create a file for this in Documentation/x86/, outlining the common cases of such .S debug info problems and the effects this has on the stack backtrace output. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi! > > > 5. Remove superfluous rsp changes. > > > > Did you test the changes? > > Yes, I verified that it didn't break suspend/resume on my system. Ok, so I can not see anything wrong, either. I'd like to understand why the original code manipulated %rsp, but... If you did testing with frame pointer on, you can get my Acked-by: Pavel Machek <pavel@ucw.cz> > > 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. Well, you are "improving debuggability", afaict. It worked well before. > > > @@ -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? It is both smaller and faster than the new code. But... Pavel
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@suse.cz>, distribute under GPLv2 @@ -33,13 +34,13 @@ ENTRY(wakeup_long64) movq saved_rip, %rax jmp *%rax -ENDPROC(wakeup_long64) +END(wakeup_long64) bogus_64_magic: jmp bogus_64_magic ENTRY(do_suspend_lowlevel) - subq $8, %rsp + FP_SAVE xorl %eax, %eax call save_processor_state @@ -70,12 +71,11 @@ ENTRY(do_suspend_lowlevel) movq %rdi, saved_rdi movq %rsi, saved_rsi - addq $8, %rsp movl $3, %edi xorl %eax, %eax call x86_acpi_enter_sleep_state + /* in case something went wrong, restore the machine status and go on */ - jmp .Lresume_point .align 4 .Lresume_point: @@ -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) .data
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. 2. do_suspend_lowlevel() is a non-leaf callable function, so save/restore the frame pointer with FP_SAVE/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. 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. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Len Brown <len.brown@intel.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: linux-pm@vger.kernel.org --- arch/x86/kernel/acpi/wakeup_64.S | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-)