From: Josh Poimboeuf <jpoimboe@redhat.com>
To: x86@kernel.org
Cc: linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Sami Tolvanen <samitolvanen@google.com>,
Sedat Dilek <sedat.dilek@gmail.com>,
Kees Cook <keescook@chromium.org>,
Nick Desaulniers <ndesaulniers@google.com>,
clang-built-linux@googlegroups.com,
Miroslav Benes <mbenes@suse.cz>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Pavel Machek <pavel@ucw.cz>
Subject: [PATCH v2 19/20] x86/power: Move restore_registers() to top of the file
Date: Thu, 21 Jan 2021 15:29:35 -0600 [thread overview]
Message-ID: <8c7f634201d26453d73fe55032cbbdc05d004387.1611263462.git.jpoimboe@redhat.com> (raw)
In-Reply-To: <cover.1611263461.git.jpoimboe@redhat.com>
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>
---
arch/x86/power/hibernate_asm_64.S | 92 +++++++++++++++----------------
1 file changed, 46 insertions(+), 46 deletions(-)
diff --git a/arch/x86/power/hibernate_asm_64.S b/arch/x86/power/hibernate_asm_64.S
index 715509d94fa3..91c4602d2b5d 100644
--- a/arch/x86/power/hibernate_asm_64.S
+++ b/arch/x86/power/hibernate_asm_64.S
@@ -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)
--
2.29.2
next prev parent reply other threads:[~2021-01-21 21:39 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-21 21:29 [PATCH v2 00/20] objtool: vmlinux.o and CLANG LTO support Josh Poimboeuf
2021-01-21 21:29 ` [PATCH v2 01/20] objtool: Fix error handling for STD/CLD warnings Josh Poimboeuf
2021-01-21 21:29 ` [PATCH v2 02/20] objtool: Fix retpoline detection in asm code Josh Poimboeuf
2021-01-21 21:29 ` [PATCH v2 03/20] objtool: Fix ".cold" section suffix check for newer versions of GCC Josh Poimboeuf
2021-01-21 21:29 ` [PATCH v2 04/20] objtool: Support retpoline jump detection for vmlinux.o Josh Poimboeuf
2021-01-21 21:29 ` [PATCH v2 05/20] x86/ftrace: Add UNWIND_HINT_FUNC annotation for ftrace_stub Josh Poimboeuf
2021-01-21 21:29 ` [PATCH v2 06/20] objtool: Assume only ELF functions do sibling calls Josh Poimboeuf
2021-01-21 21:29 ` [PATCH v2 07/20] objtool: Add asm version of STACK_FRAME_NON_STANDARD Josh Poimboeuf
2021-01-21 21:29 ` [PATCH v2 08/20] objtool: Combine UNWIND_HINT_RET_OFFSET and UNWIND_HINT_FUNC Josh Poimboeuf
2021-01-21 21:29 ` [PATCH v2 09/20] objtool: Add xen_start_kernel() to noreturn list Josh Poimboeuf
2021-01-21 21:29 ` [PATCH v2 10/20] objtool: Move unsuffixed symbol conversion to a helper function Josh Poimboeuf
2021-01-21 21:29 ` [PATCH v2 11/20] objtool: Add CONFIG_CFI_CLANG support Josh Poimboeuf
2021-01-21 21:29 ` [PATCH v2 12/20] x86/xen: Support objtool validation in xen-asm.S Josh Poimboeuf
2021-01-21 21:29 ` [PATCH v2 13/20] x86/xen: Support objtool vmlinux.o validation in xen-head.S Josh Poimboeuf
2021-01-21 21:29 ` [PATCH v2 14/20] x86/xen/pvh: Annotate indirect branch as safe Josh Poimboeuf
2021-01-22 5:17 ` Jürgen Groß
2021-01-21 21:29 ` [PATCH v2 15/20] x86/ftrace: Support objtool vmlinux.o validation in ftrace_64.S Josh Poimboeuf
2021-01-21 21:29 ` [PATCH v2 16/20] x86/acpi: Annotate indirect branch as safe Josh Poimboeuf
2021-01-21 21:29 ` [PATCH v2 17/20] x86/acpi: Support objtool validation in wakeup_64.S Josh Poimboeuf
2021-01-21 21:29 ` [PATCH v2 18/20] x86/power: Annotate indirect branches as safe Josh Poimboeuf
2021-01-21 21:29 ` Josh Poimboeuf [this message]
2021-01-21 21:29 ` [PATCH v2 20/20] x86/power: Support objtool validation in hibernate_asm_64.S Josh Poimboeuf
2021-01-21 22:38 ` [PATCH v2 00/20] objtool: vmlinux.o and CLANG LTO support Sedat Dilek
2021-01-22 15:41 ` Josh Poimboeuf
2021-01-22 21:17 ` Sami Tolvanen
2021-01-23 1:32 ` Nick Desaulniers
2021-01-23 2:26 ` Josh Poimboeuf
2021-01-23 2:31 ` Sedat Dilek
2021-01-23 2:46 ` Josh Poimboeuf
2021-01-23 2:50 ` Sedat Dilek
2021-01-25 22:43 ` Sami Tolvanen
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