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Commit 54d52573 authored by Stephen Boyd's avatar Stephen Boyd Committed by Russell King
Browse files

ARM: 6996/1: mm: Poison freed init memory 



Poisoning __init marked memory can be useful when tracking down
obscure memory corruption bugs. Therefore, poison init memory
with 0xe7fddef0 to catch bugs earlier. The poison value is an
undefined instruction in ARM mode and branch to an undefined
instruction in Thumb mode.

Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
Acked-by: default avatarNicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 7fa22bd5

arch/arm/mm/init.c

+16 −1
Original line number Diff line number Diff line
@@ -416,6 +416,17 @@ static inline int free_area(unsigned long pfn, unsigned long end, char *s) 
	return pages;

}



/*

 * Poison init memory with an undefined instruction (ARM) or a branch to an

 * undefined instruction (Thumb).

 */

static inline void poison_init_mem(void *s, size_t count)

{

	u32 *p = (u32 *)s;

	while ((count = count - 4))

		*p++ = 0xe7fddef0;

}



static inline void

free_memmap(unsigned long start_pfn, unsigned long end_pfn)

{
@@ -696,11 +707,13 @@ void free_initmem(void) 
#ifdef CONFIG_HAVE_TCM

	extern char __tcm_start, __tcm_end;



	poison_init_mem(&__tcm_start, &__tcm_end - &__tcm_start);

	totalram_pages += free_area(__phys_to_pfn(__pa(&__tcm_start)),

				    __phys_to_pfn(__pa(&__tcm_end)),

				    "TCM link");

#endif



	poison_init_mem(__init_begin, __init_end - __init_begin);

	if (!machine_is_integrator() && !machine_is_cintegrator())

		totalram_pages += free_area(__phys_to_pfn(__pa(__init_begin)),

					    __phys_to_pfn(__pa(__init_end)),
@@ -713,11 +726,13 @@ static int keep_initrd; 


void free_initrd_mem(unsigned long start, unsigned long end)

{

	if (!keep_initrd)

	if (!keep_initrd) {

		poison_init_mem((void *)start, PAGE_ALIGN(end) - start);

		totalram_pages += free_area(__phys_to_pfn(__pa(start)),

					    __phys_to_pfn(__pa(end)),

					    "initrd");

	}

}



static int __init keepinitrd_setup(char *__unused)

{