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Ingo Molnar 07a66d7c53 x86: use the right protections for split-up pagetables ... Steven Rostedt found a bug in where in his modified kernel ftrace was unable to modify the kernel text, due to the PMD itself having been marked read-only as well in split_large_page(). The fix, suggested by Linus, is to not try to 'clone' the reference protection of a huge-page, but to use the standard (and permissive) page protection bits of KERNPG_TABLE. The 'cloning' makes sense for the ptes but it's a confused and incorrect concept at the page table level - because the pagetable entry is a set of all ptes and hence cannot 'clone' any single protection attribute - the ptes can be any mixture of protections. With the permissive KERNPG_TABLE, even if the pte protections get changed after this point (due to ftrace doing code-patching or other similar activities like kprobes), the resulting combined protections will still be correct and the pte's restrictive (or permissive) protections will control it. Also update the comment. This bug was there for a long time but has not caused visible problems before as it needs a rather large read-only area to trigger. Steve possibly hacked his kernel with some really large arrays or so. Anyway, the bug is definitely worth fixing. [ Huang Ying also experienced problems in this area when writing the EFI code, but the real bug in split_large_page() was not realized back then. ] Reported-by: Steven Rostedt <rostedt@goodmis.org> Reported-by: Huang Ying <ying.huang@intel.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>		16 years ago
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alpha	cpumask: Use cpu_*_mask accessors code: alpha	16 years ago
arm	[ARM] 5405/1: ep93xx: remove unused gesbc9312.h header	16 years ago
avr32	[ARM] 5400/1: Add support for inverted rdy_busy pin for Atmel nand device controller	16 years ago
blackfin	Blackfin arch: Remove outdated code	16 years ago
cris	Merge branch 'syscalls' of git://git390.osdl.marist.edu/pub/scm/linux-2.6	16 years ago
frv	FRV: in_interrupt() requires #inclusion of linux/hardirq.h not asm/hardirq.h now	16 years ago
h8300	Merge branch 'syscalls' of git://git390.osdl.marist.edu/pub/scm/linux-2.6	16 years ago
ia64	mm: fix memmap init for handling memory hole	16 years ago
m32r	eeprom: More consistent symbol names	16 years ago
m68k	m68knommu: remove the no longer used PCI support option	16 years ago
m68knommu	m68knommu: fix 5329 ColdFire periphal addressing	16 years ago
mips	x86: spinlocks: define dummy __raw_spin_is_contended	16 years ago
mn10300	[CVE-2009-0029] Rename old_readdir to sys_old_readdir	16 years ago
parisc	Documentation: move DMA-mapping.txt to Doc/PCI/	16 years ago
powerpc	Merge branch 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc	16 years ago
s390	[S390] fix "mem=" handling in case of standby memory	16 years ago
sh	sh: Fix up T-bit error handling in SH-4A mutex fastpath.	16 years ago
sparc	sparc64: Fix probe_kernel_{read,write}().	16 years ago
um	mm: invoke oom-killer from page fault	16 years ago
x86	x86: use the right protections for split-up pagetables	16 years ago
xtensa	byteorder: make swab.h include asm/swab.h like a regular header	16 years ago
.gitignore	…
Kconfig	[CVE-2009-0029] System call wrapper infrastructure	16 years ago