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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: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/8c7f634201d26453d73fe55032cbbdc05d004387.1611263462.git.jpoimboe@redhat.com
This commit is contained in:
Josh Poimboeuf 2021-01-21 15:29:35 -06:00
parent b682369d47
commit 125f0b7d24
1 changed files with 46 additions and 46 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

92
arch/x86/power/hibernate_asm_64.S
View File

@ -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)