Commit 125f0b7d authored by Josh Poimboeuf's avatar Josh Poimboeuf
Browse files

x86/power: Move restore_registers() to top of the file 



Because restore_registers() is page-aligned, the assembler inexplicably
adds an unreachable jump from after the end of the previous function to
the beginning of restore_registers().

That confuses objtool, understandably.  It also creates significant text
fragmentation.  As a result, most of the object file is wasted text
(nops).

Move restore_registers() to the beginning of the file to both prevent
the text fragmentation and avoid the dead jump instruction.

$ size /tmp/hibernate_asm_64.before.o /tmp/hibernate_asm_64.after.o
   text	   data	    bss	    dec	    hex	filename
   4415	      0	      0	   4415	   113f	/tmp/hibernate_asm_64.before.o
    524	      0	      0	    524	    20c	/tmp/hibernate_asm_64.after.o

Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/8c7f634201d26453d73fe55032cbbdc05d004387.1611263462.git.jpoimboe@redhat.com
parent b682369d

arch/x86/power/hibernate_asm_64.S

+46 −46
Original line number Diff line number Diff line
@@ -23,6 +23,52 @@ 
#include <asm/frame.h>

#include <asm/nospec-branch.h>



	 /* code below belongs to the image kernel */

	.align PAGE_SIZE

SYM_FUNC_START(restore_registers)

	/* go back to the original page tables */

	movq    %r9, %cr3



	/* Flush TLB, including "global" things (vmalloc) */

	movq	mmu_cr4_features(%rip), %rax

	movq	%rax, %rdx

	andq	$~(X86_CR4_PGE), %rdx

	movq	%rdx, %cr4;  # turn off PGE

	movq	%cr3, %rcx;  # flush TLB

	movq	%rcx, %cr3

	movq	%rax, %cr4;  # turn PGE back on



	/* We don't restore %rax, it must be 0 anyway */

	movq	$saved_context, %rax

	movq	pt_regs_sp(%rax), %rsp

	movq	pt_regs_bp(%rax), %rbp

	movq	pt_regs_si(%rax), %rsi

	movq	pt_regs_di(%rax), %rdi

	movq	pt_regs_bx(%rax), %rbx

	movq	pt_regs_cx(%rax), %rcx

	movq	pt_regs_dx(%rax), %rdx

	movq	pt_regs_r8(%rax), %r8

	movq	pt_regs_r9(%rax), %r9

	movq	pt_regs_r10(%rax), %r10

	movq	pt_regs_r11(%rax), %r11

	movq	pt_regs_r12(%rax), %r12

	movq	pt_regs_r13(%rax), %r13

	movq	pt_regs_r14(%rax), %r14

	movq	pt_regs_r15(%rax), %r15

	pushq	pt_regs_flags(%rax)

	popfq



	/* Saved in save_processor_state. */

	lgdt	saved_context_gdt_desc(%rax)



	xorl	%eax, %eax



	/* tell the hibernation core that we've just restored the memory */

	movq	%rax, in_suspend(%rip)



	ret

SYM_FUNC_END(restore_registers)



SYM_FUNC_START(swsusp_arch_suspend)

	movq	$saved_context, %rax

	movq	%rsp, pt_regs_sp(%rax)
@@ -102,49 +148,3 @@ SYM_CODE_START(core_restore_code) 
	ANNOTATE_RETPOLINE_SAFE

	jmpq	*%r8

SYM_CODE_END(core_restore_code)
 


	 /* code below belongs to the image kernel */

	.align PAGE_SIZE

SYM_FUNC_START(restore_registers)

	/* go back to the original page tables */

	movq    %r9, %cr3



	/* Flush TLB, including "global" things (vmalloc) */

	movq	mmu_cr4_features(%rip), %rax

	movq	%rax, %rdx

	andq	$~(X86_CR4_PGE), %rdx

	movq	%rdx, %cr4;  # turn off PGE

	movq	%cr3, %rcx;  # flush TLB

	movq	%rcx, %cr3

	movq	%rax, %cr4;  # turn PGE back on



	/* We don't restore %rax, it must be 0 anyway */

	movq	$saved_context, %rax

	movq	pt_regs_sp(%rax), %rsp

	movq	pt_regs_bp(%rax), %rbp

	movq	pt_regs_si(%rax), %rsi

	movq	pt_regs_di(%rax), %rdi

	movq	pt_regs_bx(%rax), %rbx

	movq	pt_regs_cx(%rax), %rcx

	movq	pt_regs_dx(%rax), %rdx

	movq	pt_regs_r8(%rax), %r8

	movq	pt_regs_r9(%rax), %r9

	movq	pt_regs_r10(%rax), %r10

	movq	pt_regs_r11(%rax), %r11

	movq	pt_regs_r12(%rax), %r12

	movq	pt_regs_r13(%rax), %r13

	movq	pt_regs_r14(%rax), %r14

	movq	pt_regs_r15(%rax), %r15

	pushq	pt_regs_flags(%rax)

	popfq



	/* Saved in save_processor_state. */

	lgdt	saved_context_gdt_desc(%rax)



	xorl	%eax, %eax



	/* tell the hibernation core that we've just restored the memory */

	movq	%rax, in_suspend(%rip)



	ret

SYM_FUNC_END(restore_registers)