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path: root/include/asm-arm/processor.h
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2006-12-13[ARM] 4016/1: prefetch macro is wrong wrt gcc's "delete-null-pointer-checks"Nicolas Pitre
optimization The gcc manual says: |`-fdelete-null-pointer-checks' | Use global dataflow analysis to identify and eliminate useless | checks for null pointers. The compiler assumes that dereferencing | a null pointer would have halted the program. If a pointer is | checked after it has already been dereferenced, it cannot be null. | Enabled at levels `-O2', `-O3', `-Os'. Now the problem can be seen with this test case: #include <linux/prefetch.h> extern void bar(char *x); void foo(char *x) { prefetch(x); if (x) bar(x); } Because the constraint to the inline asm used in the prefetch() macro is a memory operand, gcc assumes that the asm code does dereference the pointer and the delete-null-pointer-checks optimization kicks in. Inspection of generated assembly for the above example shows that bar() is indeed called unconditionally without any test on the value of x. Of course in the prefetch case there is no real dereference and it cannot be assumed that a null pointer would have been caught at that point. This causes kernel oopses with constructs like hlist_for_each_entry() where the list's 'next' content is prefetched before the pointer is tested against NULL, and only when gcc feels like applying this optimization which doesn't happen all the time with more complex code. It appears that the way to prevent delete-null-pointer-checks optimization to occur in this case is to make prefetch() into a static inline function instead of a macro. At least this is what is done on x86_64 where a similar inline asm memory operand is used (I presume they would have seen the same problem if it didn't work) and resulting code for the above example confirms that. An alternative would consist of replacing the memory operand by a register operand containing the pointer, and use the addressing mode explicitly in the asm template. But that would be less optimal than an offsettable memory reference. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2006-11-30[ARM] Include asm/elf.h instead of asm/procinfo.hRussell King
These files want to provide/access ELF hwcap information, so should be including asm/elf.h rather than asm/procinfo.h Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2006-01-13[ARM] start_thread fixup for nommu modeHyok S. Choi
This patch supports start_thread in nommu mode which requires the base index register. Signed-off-by: Hyok S. Choi <hyok.choi@samsung.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2006-01-12[PATCH] arm: task_stack_page()Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-12[PATCH] arm: task_pt_regs()Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-05-05[PATCH] ARM: Fix kernel stack offset calculationsRussell King
Various places in the ARM kernel implicitly assumed that kernel stacks are always 8K due to hard coded constants. Replace these constants with definitions. Correct the allowable range of kernel stack pointer values within the allocation. Arrange for the entire kernel stack to be zeroed, not just the upper 4K if CONFIG_DEBUG_STACK_USAGE is set. Signed-off-by: Russell King <rmk@arm.linux.org.uk>
2005-04-16Linux-2.6.12-rc2Linus Torvalds
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!