This is a note to let you know that I've just added the patch titled
x86/asm: Reorder early variables
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-asm-reorder-early-variables.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 412ac67de3c22418683b90fb02c0926a1789278c
Author: Jiri Slaby <jirislaby@xxxxxxxxxx>
Date: Thu Oct 3 11:52:37 2019 +0200
x86/asm: Reorder early variables
[ Upstream commit 1a8770b746bd05ef68217989cd723b2c24d2208d ]
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@xxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: x86-ml <x86@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20191003095238.29831-1-jslaby@xxxxxxx
Stable-dep-of: 3b2f2d22fb42 ("crypto: x86/aegis128 - access 32-bit arguments as 32-bit")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index f3d3e9646a99b..f00d7c0c1c86b 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)
