From: Borislav Petkov <bp@alien8.de>
To: Jiri Slaby <jslaby@suse.cz>
Cc: mingo@redhat.com, linux-arch@vger.kernel.org,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org
Subject: Re: [PATCH v7 11/28] x86/asm/head: annotate data appropriatelly
Date: Mon, 25 Feb 2019 15:53:31 +0100 [thread overview]
Message-ID: <20190225145330.GF26145@zn.tnic> (raw)
In-Reply-To: <20190130124711.12463-12-jslaby@suse.cz>
On Wed, Jan 30, 2019 at 01:46:54PM +0100, Jiri Slaby wrote:
> Use the new SYM_DATA, SYM_DATA_START, and SYM_DATA_END in both 32 and 64
> bit heads. In the 64-bit version, define also
> SYM_DATA_START_PAGE_ALIGNED locally using the new SYM_START. It is used
> in the code instead of NEXT_PAGE() which was defined in this file and
> has been using the obsolete macro GLOBAL().
>
> Now, the data in the 64-bit object file look sane:
> Value Size Type Bind Vis Ndx Name
> 0000 4096 OBJECT GLOBAL DEFAULT 15 init_level4_pgt
> 1000 4096 OBJECT GLOBAL DEFAULT 15 level3_kernel_pgt
> 2000 2048 OBJECT GLOBAL DEFAULT 15 level2_kernel_pgt
^^^^
Except that this size is kinda misleading.
We end up using a whole page for this because of the alignment of the
next one but because we're not filing it up properly, the symbol has the
size of a half a page:
ffffffff8200f000 <level2_kernel_pgt>:
ffffffff8200f7f6: 00 00 add %al,(%rax)
ffffffff8200f7f8: e3 01 jrcxz ffffffff8200f7fb <level2_kernel_pgt+0x7fb>
ffffffff8200f7fa: e0 1f loopne ffffffff8200f81b <level2_kernel_pgt+0x81b>
...
ffffffff82010000 <level2_fixmap_pgt>:
That's a whole page with 2K padding.
You can do this in a prepatch:
---
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 5b7a3b430dea..93a9fd294962 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -448,6 +448,7 @@ SYM_DATA_START_PAGE_ALIGNED(level2_kernel_pgt)
*/
PMDS(0, __PAGE_KERNEL_LARGE_EXEC,
KERNEL_IMAGE_SIZE/PMD_SIZE)
+ .fill 512 - KERNEL_IMAGE_SIZE/PMD_SIZE,8,0
SYM_DATA_END(level2_kernel_pgt)
SYM_DATA_START_PAGE_ALIGNED(level2_fixmap_pgt)
---
and then we get the proper symbol size:
69952: ffffffff8200f000 4096 OBJECT GLOBAL DEFAULT 11 level2_kernel_pgt
Thx.
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
next prev parent reply other threads:[~2019-02-25 14:53 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-30 12:46 [PATCH v7 00/28] New macros for assembler symbols Jiri Slaby
2019-01-30 12:46 ` [PATCH v7 01/28] linkage: new " Jiri Slaby
2019-01-31 16:00 ` Borislav Petkov
2019-02-01 13:53 ` Jiri Slaby
2019-01-30 12:46 ` [PATCH v7 02/28] x86/asm/suspend: drop ENTRY from local data Jiri Slaby
2019-01-30 15:12 ` [tip:x86/cleanups] x86/asm/suspend: Drop " tip-bot for Jiri Slaby
2019-01-30 12:46 ` [PATCH v7 03/28] x86/asm/suspend: use SYM_DATA for data Jiri Slaby
2019-02-04 20:18 ` Borislav Petkov
2019-02-05 7:34 ` Jiri Slaby
2019-02-05 8:07 ` Borislav Petkov
2019-01-30 12:46 ` [PATCH v7 04/28] x86/asm: annotate relocate_kernel Jiri Slaby
2019-02-08 19:53 ` Borislav Petkov
2019-01-30 12:46 ` [PATCH v7 05/28] x86/asm/entry: annotate THUNKs Jiri Slaby
2019-02-09 11:25 ` Borislav Petkov
2019-02-12 10:27 ` Jiri Slaby
2019-02-12 11:05 ` Borislav Petkov
2019-02-12 11:38 ` Jiri Slaby
2019-02-12 11:46 ` Borislav Petkov
2019-02-12 11:51 ` Jiri Slaby
2019-02-12 12:13 ` Borislav Petkov
2019-02-14 10:03 ` Jiri Slaby
2019-02-14 10:34 ` Borislav Petkov
2019-01-30 12:46 ` [PATCH v7 06/28] x86/asm: annotate local pseudo-functions Jiri Slaby
2019-02-09 12:24 ` Borislav Petkov
2019-01-30 12:46 ` [PATCH v7 07/28] x86/asm/crypto: annotate local functions Jiri Slaby
2019-02-25 10:13 ` Borislav Petkov
2019-01-30 12:46 ` [PATCH v7 08/28] x86/boot/compressed: " Jiri Slaby
2019-01-30 12:46 ` [PATCH v7 09/28] x86/asm: annotate aliases Jiri Slaby
2019-01-30 12:46 ` [PATCH v7 10/28] x86/asm/entry: annotate interrupt symbols properly Jiri Slaby
2019-01-30 12:46 ` [PATCH v7 11/28] x86/asm/head: annotate data appropriatelly Jiri Slaby
2019-02-25 14:53 ` Borislav Petkov [this message]
2019-01-30 12:46 ` [PATCH v7 12/28] x86/boot/compressed: " Jiri Slaby
2019-01-30 12:46 ` [PATCH v7 13/28] um: " Jiri Slaby
2019-01-30 12:46 ` [PATCH v7 14/28] xen/pvh: " Jiri Slaby
2019-01-30 12:46 ` [PATCH v7 15/28] x86/asm/purgatory: start using annotations Jiri Slaby
2019-01-30 12:46 ` [PATCH v7 16/28] x86/asm: do not annotate functions by GLOBAL Jiri Slaby
2019-01-30 12:47 ` [PATCH v7 17/28] x86/asm: use SYM_INNER_LABEL instead of GLOBAL Jiri Slaby
2019-01-30 12:47 ` [PATCH v7 18/28] x86/asm/realmode: use SYM_DATA_* " Jiri Slaby
2019-01-30 12:47 ` [PATCH v7 19/28] x86/asm: kill the last GLOBAL user and remove the macro Jiri Slaby
2019-01-30 12:47 ` [PATCH v7 20/28] x86/asm: make some functions local Jiri Slaby
2019-01-30 12:47 ` [PATCH v7 21/28] x86/asm/ftrace: mark function_hook as function Jiri Slaby
2019-01-30 12:47 ` [PATCH v7 22/28] x86_64/asm: add ENDs to some functions and relabel with SYM_CODE_* Jiri Slaby
2019-01-30 12:47 ` [PATCH v7 23/28] x86_64/asm: change all ENTRY+END to SYM_CODE_* Jiri Slaby
2019-01-30 12:47 ` [PATCH v7 24/28] x86_64/asm: change all ENTRY+ENDPROC to SYM_FUNC_* Jiri Slaby
2019-01-30 12:47 ` [PATCH v7 25/28] x86_32/asm: add ENDs to some functions and relabel with SYM_CODE_* Jiri Slaby
2019-01-30 12:47 ` [PATCH v7 26/28] x86_32/asm: change all ENTRY+END to SYM_CODE_* Jiri Slaby
2019-01-30 12:47 ` [PATCH v7 27/28] x86_32/asm: change all ENTRY+ENDPROC to SYM_FUNC_* Jiri Slaby
2019-01-30 12:47 ` [PATCH v7 28/28] x86/asm: replace WEAK uses by SYM_INNER_LABEL_ALIGN Jiri Slaby
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