From 54d525735140e930d87c5afd1b0b3393ffdac021 Mon Sep 17 00:00:00 2001 From: Stephen Boyd Date: Thu, 7 Jul 2011 18:43:36 +0100 Subject: [PATCH] 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: Stephen Boyd Acked-by: Nicolas Pitre Signed-off-by: Russell King --- arch/arm/mm/init.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c index 2c2cce9cd8c8..fdc87f9bda55 100644 --- a/arch/arm/mm/init.c +++ b/arch/arm/mm/init.c @@ -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)), @@ -713,10 +726,12 @@ 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) -- GitLab