From: "tip-bot2 for Jiri Slaby" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Jiri Slaby <jslaby@suse.cz>, Borislav Petkov <bp@suse.de>,
Andy Lutomirski <luto@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Juergen Gross <jgross@suse.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>, "x86-ml" <x86@kernel.org>,
Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
linux-kernel@vger.kernel.org
Subject: [tip: x86/asm] x86/asm: Reorder early variables
Date: Sat, 05 Oct 2019 10:14:57 -0000 [thread overview]
Message-ID: <157027049768.9978.11005637397803915038.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20191003095238.29831-1-jslaby@suse.cz>
The following commit has been merged into the x86/asm branch of tip:
Commit-ID: 1a8770b746bd05ef68217989cd723b2c24d2208d
Gitweb: https://git.kernel.org/tip/1a8770b746bd05ef68217989cd723b2c24d2208d
Author: Jiri Slaby <jslaby@suse.cz>
AuthorDate: Thu, 03 Oct 2019 11:52:37 +02:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Sat, 05 Oct 2019 12:11:00 +02:00
x86/asm: Reorder early variables
Moving early_recursion_flag (4 bytes) after early_level4_pgt (4k) and
early_dynamic_pgts (256k) saves 4k which are used for alignment of
early_level4_pgt after early_recursion_flag.
The real improvement is merely on the source code side. Previously it
was:
* __INITDATA + .balign
* early_recursion_flag variable
* a ton of CPP MACROS
* __INITDATA (again)
* early_top_pgt and early_recursion_flag variables
* .data
Now, it is a bit simpler:
* a ton of CPP MACROS
* __INITDATA + .balign
* early_top_pgt and early_recursion_flag variables
* early_recursion_flag variable
* .data
On the binary level the change looks like this:
Before:
(sections)
12 .init.data 00042000 0000000000000000 0000000000000000 00008000 2**12
(symbols)
000000 4 OBJECT GLOBAL DEFAULT 22 early_recursion_flag
001000 4096 OBJECT GLOBAL DEFAULT 22 early_top_pgt
002000 0x40000 OBJECT GLOBAL DEFAULT 22 early_dynamic_pgts
After:
(sections)
12 .init.data 00041004 0000000000000000 0000000000000000 00008000 2**12
(symbols)
000000 4096 OBJECT GLOBAL DEFAULT 22 early_top_pgt
001000 0x40000 OBJECT GLOBAL DEFAULT 22 early_dynamic_pgts
041000 4 OBJECT GLOBAL DEFAULT 22 early_recursion_flag
So the resulting vmlinux is smaller by 4k with my toolchain as many
other variables can be placed after early_recursion_flag to fill the
rest of the page. Note that this is only .init data, so it is freed
right after being booted anyway. Savings on-disk are none -- compression
of zeros is easy, so the size of bzImage is the same pre and post the
change.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20191003095238.29831-1-jslaby@suse.cz
---
arch/x86/kernel/head_64.S | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index f3d3e96..f00d7c0 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -335,12 +335,6 @@ early_idt_handler_common:
jmp restore_regs_and_return_to_kernel
END(early_idt_handler_common)
- __INITDATA
-
- .balign 4
-GLOBAL(early_recursion_flag)
- .long 0
-
#define NEXT_PAGE(name) \
.balign PAGE_SIZE; \
GLOBAL(name)
@@ -375,6 +369,8 @@ GLOBAL(name)
.endr
__INITDATA
+ .balign 4
+
NEXT_PGD_PAGE(early_top_pgt)
.fill 512,8,0
.fill PTI_USER_PGD_FILL,8,0
@@ -382,6 +378,9 @@ NEXT_PGD_PAGE(early_top_pgt)
NEXT_PAGE(early_dynamic_pgts)
.fill 512*EARLY_DYNAMIC_PAGE_TABLES,8,0
+GLOBAL(early_recursion_flag)
+ .long 0
+
.data
#if defined(CONFIG_XEN_PV) || defined(CONFIG_PVH)
prev parent reply other threads:[~2019-10-05 10:15 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-03 9:52 [PATCH 1/2] x86/asm: Reorder early variables Jiri Slaby
2019-10-03 9:52 ` [PATCH 2/2] x86/asm: Make boot_gdt_descr local Jiri Slaby
2019-10-05 10:14 ` [tip: x86/asm] " tip-bot2 for Jiri Slaby
2019-10-05 10:14 ` tip-bot2 for Jiri Slaby [this message]
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