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Date: Tue, 7 Jul 2015 13:19:49 -0700
From: Yinghai Lu <yinghai@...nel.org>
To: Kees Cook <keescook@...omium.org>,
"H. Peter Anvin" <hpa@...or.com>, Baoquan He <bhe@...hat.com>
Cc: linux-kernel@...r.kernel.org, Yinghai Lu <yinghai@...nel.org>,
Junjie Mao <eternal.n08@...il.com>,
Josh Triplett <josh@...htriplett.org>,
Matt Fleming <matt.fleming@...el.com>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 03/42] x86, boot: Fix run_size calculation
While looking at the boot code to add mem mapping for kasl
with 64bit above 4G support, I found that e6023367d779 ("x86, kaslr: Prevent
.bss from overlaping initrd") and later introduced way to get kernel run_size
and pass it around. At first run_size calculation is via perl and then
changed to shell scripts.
At first, that calculation is not right in the shell scripts:
it is using bss offset in the file plus bss/brk section size.
run_size=$(( $offsetA + $sizeA + $sizeB ))
Idx Name Size VMA LMA File off Algn
...
24 .bss 000a1000 ffffffff825e0000 00000000025e0000 019e0000 2**12
ALLOC
25 .brk 00026000 ffffffff82681000 0000000002681000 019e0000 2**0
ALLOC
that run_size will be 27947008.
it has extra not needed size as
1. we have hole between the sections in file to get aligned in file.
2. start of text is from 0x200000 in elf file.
[Nr] Name Type Address Offset
Size EntSize Flags Link Info Align
...
[25] .bss NOBITS ffffffff825e0000 019e0000
00000000000a1000 0000000000000000 WA 0 0 4096
[26] .brk NOBITS ffffffff82681000 019e0000
0000000000026000 0000000000000000 WA 0 0 1
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
LOAD 0x0000000000200000 0xffffffff81000000 0x0000000001000000
0x00000000013a9000 0x00000000013a9000 R E 200000
LOAD 0x0000000001600000 0xffffffff82400000 0x0000000002400000
0x00000000000ed000 0x00000000000ed000 RW 200000
LOAD 0x0000000001800000 0x0000000000000000 0x00000000024ed000
0x0000000000013698 0x0000000000013698 RW 200000
LOAD 0x0000000001901000 0xffffffff82501000 0x0000000002501000
0x00000000000df000 0x00000000001a6000 RWE 200000
NOTE 0x0000000000e9d7dc 0xffffffff81c9d7dc 0x0000000001c9d7dc
0x0000000000000024 0x0000000000000024 4
Section to Segment mapping:
Segment Sections...
00 .text .notes ..
01 .data .vvar
02 .data..percpu
03 .init.text ... .bss .brk
04 .notes
During decompress_kernel, parse_elf will move forward section to run time position.
parse_elf: [0x009a000000-0x009b3a8fff] <=== [0x009a200000-0x009b5a8fff]
parse_elf: [0x009b400000-0x009b4ecfff] <=== [0x009b600000-0x009b6ecfff]
parse_elf: [0x009b4ed000-0x009b500697] <=== [0x009b800000-0x009b813697]
parse_elf: [0x009b501000-0x009b5dffff] <=== [0x009b901000-0x009b9dffff]
Secondly it is not necessary. As run_size is simple constant, we don't
need to pass it around and we already have voffset.h for that.
We can share voffset.h between misc.c and header.S instead of adding
other way to get run_size.
In this patch, we move voffset.h creation code to boot/compressed/Makefile.
Dependence was:
boot/header.S ==> boot/voffset.h ==> vmlinux
boot/header.S ==> compressed/vmlinux ==> compressed/misc.c
Now become:
boot/header.S ==> compressed/vmlinux ==> compressed/misc.c ==> boot/voffset.h ==> vmlinux
Use macro in misc.c to replace passed run_size.
Fixes: e6023367d779 ("x86, kaslr: Prevent .bss from overlaping initrd")
Cc: Junjie Mao <eternal.n08@...il.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Josh Triplett <josh@...htriplett.org>
Cc: Matt Fleming <matt.fleming@...el.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Yinghai Lu <yinghai@...nel.org>
---
arch/x86/boot/Makefile | 11 +----------
arch/x86/boot/compressed/Makefile | 12 ++++++++++++
arch/x86/boot/compressed/misc.c | 3 +++
3 files changed, 16 insertions(+), 10 deletions(-)
diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
index 57bbf2f..4d27e8b 100644
--- a/arch/x86/boot/Makefile
+++ b/arch/x86/boot/Makefile
@@ -77,15 +77,6 @@ $(obj)/vmlinux.bin: $(obj)/compressed/vmlinux FORCE
SETUP_OBJS = $(addprefix $(obj)/,$(setup-y))
-sed-voffset := -e 's/^\([0-9a-fA-F]*\) [ABCDGRSTVW] \(_text\|_end\)$$/\#define VO_\2 0x\1/p'
-
-quiet_cmd_voffset = VOFFSET $@
- cmd_voffset = $(NM) $< | sed -n $(sed-voffset) > $@
-
-targets += voffset.h
-$(obj)/voffset.h: vmlinux FORCE
- $(call if_changed,voffset)
-
sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [ABCDGRSTVW] \(startup_32\|startup_64\|efi32_stub_entry\|efi64_stub_entry\|efi_pe_entry\|input_data\|_end\|z_.*\)$$/\#define ZO_\2 0x\1/p'
quiet_cmd_zoffset = ZOFFSET $@
@@ -97,7 +88,7 @@ $(obj)/zoffset.h: $(obj)/compressed/vmlinux FORCE
AFLAGS_header.o += -I$(obj)
-$(obj)/header.o: $(obj)/voffset.h $(obj)/zoffset.h
+$(obj)/header.o: $(obj)/zoffset.h
LDFLAGS_setup.elf := -T
$(obj)/setup.elf: $(src)/setup.ld $(SETUP_OBJS) FORCE
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 0a291cd..d9fee82 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -40,6 +40,18 @@ LDFLAGS_vmlinux := -T
hostprogs-y := mkpiggy
HOST_EXTRACFLAGS += -I$(srctree)/tools/include
+sed-voffset := -e 's/^\([0-9a-fA-F]*\) [ABCDGRSTVW] \(_text\|_end\)$$/\#define VO_\2 _AC(0x\1,UL)/p'
+
+quiet_cmd_voffset = VOFFSET $@
+ cmd_voffset = $(NM) $< | sed -n $(sed-voffset) > $@
+
+targets += ../voffset.h
+
+$(obj)/../voffset.h: vmlinux FORCE
+ $(call if_changed,voffset)
+
+$(obj)/misc.o: $(obj)/../voffset.h
+
vmlinux-objs-y := $(obj)/vmlinux.lds $(obj)/head_$(BITS).o $(obj)/misc.o \
$(obj)/string.o $(obj)/cmdline.o \
$(obj)/piggy.o $(obj)/cpuflags.o
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index ebf72ce..a88b591 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -11,6 +11,7 @@
#include "misc.h"
#include "../string.h"
+#include "../voffset.h"
/* WARNING!!
* This code is compiled with -fPIC and it is relocated dynamically
@@ -393,6 +394,8 @@ asmlinkage __visible void *decompress_kernel(void *rmode, memptr heap,
lines = real_mode->screen_info.orig_video_lines;
cols = real_mode->screen_info.orig_video_cols;
+ run_size = VO__end - VO__text;
+
console_init();
debug_putstr("early console in decompress_kernel\n");
--
1.8.4.5
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