* [PATCH 1/2] x86/asm: Reorder early variables
@ 2019-10-03 9:52 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] x86/asm: Reorder early variables tip-bot2 for Jiri Slaby
0 siblings, 2 replies; 4+ messages in thread
From: Jiri Slaby @ 2019-10-03 9:52 UTC (permalink / raw)
To: bp; +Cc: tglx, mingo, hpa, x86, linux-kernel, Jiri Slaby
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>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
---
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 f3d3e9646a99..f00d7c0c1c86 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)
--
2.23.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH 2/2] x86/asm: Make boot_gdt_descr local
2019-10-03 9:52 [PATCH 1/2] x86/asm: Reorder early variables Jiri Slaby
@ 2019-10-03 9:52 ` Jiri Slaby
2019-10-05 10:14 ` [tip: x86/asm] " tip-bot2 for Jiri Slaby
2019-10-05 10:14 ` [tip: x86/asm] x86/asm: Reorder early variables tip-bot2 for Jiri Slaby
1 sibling, 1 reply; 4+ messages in thread
From: Jiri Slaby @ 2019-10-03 9:52 UTC (permalink / raw)
To: bp; +Cc: tglx, mingo, hpa, x86, linux-kernel, Jiri Slaby
As far as I can see, it was never used outside head_32.S. Not even when
added in 2004. So make it local.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
---
arch/x86/kernel/head_32.S | 2 --
1 file changed, 2 deletions(-)
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index 30f9cb2c0b55..7feb953e10d2 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -597,8 +597,6 @@ int_msg:
*/
.data
-.globl boot_gdt_descr
-
ALIGN
# early boot GDT descriptor (must use 1:1 address mapping)
.word 0 # 32 bit align gdt_desc.address
--
2.23.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [tip: x86/asm] x86/asm: Make boot_gdt_descr local
2019-10-03 9:52 ` [PATCH 2/2] x86/asm: Make boot_gdt_descr local Jiri Slaby
@ 2019-10-05 10:14 ` tip-bot2 for Jiri Slaby
0 siblings, 0 replies; 4+ messages in thread
From: tip-bot2 for Jiri Slaby @ 2019-10-05 10:14 UTC (permalink / raw)
To: linux-tip-commits
Cc: Jiri Slaby, Borislav Petkov, H. Peter Anvin, Ingo Molnar,
Thomas Gleixner, x86-ml, Ingo Molnar, Borislav Petkov,
linux-kernel
The following commit has been merged into the x86/asm branch of tip:
Commit-ID: 5aa5cbd2e95e0079b2cc6b4b66f0d0de5e0fbbfd
Gitweb: https://git.kernel.org/tip/5aa5cbd2e95e0079b2cc6b4b66f0d0de5e0fbbfd
Author: Jiri Slaby <jslaby@suse.cz>
AuthorDate: Thu, 03 Oct 2019 11:52:38 +02:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Sat, 05 Oct 2019 12:11:05 +02:00
x86/asm: Make boot_gdt_descr local
As far as I can see, it was never used outside of head_32.S. Not even
when added in 2004. So make it local.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20191003095238.29831-2-jslaby@suse.cz
---
arch/x86/kernel/head_32.S | 2 --
1 file changed, 2 deletions(-)
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index 30f9cb2..7feb953 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -597,8 +597,6 @@ int_msg:
*/
.data
-.globl boot_gdt_descr
-
ALIGN
# early boot GDT descriptor (must use 1:1 address mapping)
.word 0 # 32 bit align gdt_desc.address
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [tip: x86/asm] x86/asm: Reorder early variables
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-bot2 for Jiri Slaby
1 sibling, 0 replies; 4+ messages in thread
From: tip-bot2 for Jiri Slaby @ 2019-10-05 10:14 UTC (permalink / raw)
To: linux-tip-commits
Cc: Jiri Slaby, Borislav Petkov, Andy Lutomirski, H. Peter Anvin,
Ingo Molnar, Josh Poimboeuf, Juergen Gross, Peter Zijlstra,
Thomas Gleixner, x86-ml, Ingo Molnar, Borislav Petkov,
linux-kernel
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)
^ permalink raw reply related [flat|nested] 4+ messages in thread
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