From: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
To: akpm@osdl.org
Cc: torvalds@osdl.org, linux-kernel@vger.kernel.org, ak@suse.de
Subject: [PATCH] Remove data-header and code overlap in boot/setup.S
Date: Tue, 16 Nov 2004 13:52:45 -0800 [thread overview]
Message-ID: <20041116135245.A7475@unix-os.sc.intel.com> (raw)
Bug:
The setup.S data and code is not cleanly separated. The current space
reserved for setup header is not enough to fit the complete header. As a
result, part of the header (EDDBUF) will overwrite the initial code.
I haven't seen any negative impact of this bug. As, by the time the setup
code is overwritten, we would have finished executing it anyway. But,
I think it is better to separate the header and code and prevent this
data_overwriting_the_code condition.
The atatched patch adds some space in the header to fit all the data listed
in Documentation/i386/zero-page.txt for both i386 and x86_64
(and updates zero-page.txt).
Signed-off-by:: "Venkatesh Pallipadi" <venkatesh.pallipadi@intel.com>
--- linux-2.6.10-rc1-bk22//arch/i386/boot/setup.S.org 2004-11-12 16:30:09.000000000 -0800
+++ linux-2.6.10-rc1-bk22//arch/i386/boot/setup.S 2004-11-12 17:46:42.000000000 -0800
@@ -162,7 +162,9 @@ ramdisk_max: .long (-__PAGE_OFFSET-(512
# the contents of an initrd
trampoline: call start_of_setup
- .space 1024
+ .align 16
+ # The offset at this point is 0x240
+ .space (0x7ff-0x240+1) # E820 & EDD space (ending at 0x7ff)
# End of setup header #####################################################
start_of_setup:
--- linux-2.6.10-rc1-bk22//arch/x86_64/boot/setup.S.org 2004-11-12 17:40:56.000000000 -0800
+++ linux-2.6.10-rc1-bk22//arch/x86_64/boot/setup.S 2004-11-12 17:47:59.000000000 -0800
@@ -158,7 +158,9 @@ cmd_line_ptr: .long 0 # (Header versio
ramdisk_max: .long 0xffffffff
trampoline: call start_of_setup
- .space 1024
+ .align 16
+ # The offset at this point is 0x240
+ .space (0x7ff-0x240+1) # E820 & EDD space (ending at 0x7ff)
# End of setup header #####################################################
start_of_setup:
--- linux-2.6.10-rc1-bk22//Documentation/i386/zero-page.txt.org 2004-11-12 13:46:22.000000000 -0800
+++ linux-2.6.10-rc1-bk22//Documentation/i386/zero-page.txt 2004-11-12 17:48:54.000000000 -0800
@@ -74,6 +74,10 @@ Offset Type Description
0x21c unsigned long INITRD_SIZE, size in bytes of ramdisk image
0x220 4 bytes (setup.S)
0x224 unsigned short setup.S heap end pointer
+0x226 unsigned short zero_pad
+0x228 unsigned long cmd_line_ptr
+0x22c unsigned long ramdisk_max
+0x230 16 bytes trampoline
0x290 - 0x2cf EDD_MBR_SIG_BUFFER (edd.S)
0x2d0 - 0x600 E820MAP
0x600 - 0x7ff EDDBUF (edd.S) for disk signature read sector
reply other threads:[~2004-11-16 22:00 UTC|newest]
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