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| author | Russell King <rmk+kernel@arm.linux.org.uk> | 2009-11-01 17:44:24 +0000 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2009-11-02 16:59:59 +0000 |
| commit | 4b46d6416548fb6a0940dfd9911fd895eb6247b3 (patch) | |
| tree | c2a890342019c9df5e6187ad185a28208b786341 | |
| parent | 6603a4fd5195a004dec5f9568e38ff76bae630c1 (diff) | |
| download | lwn-4b46d6416548fb6a0940dfd9911fd895eb6247b3.tar.gz lwn-4b46d6416548fb6a0940dfd9911fd895eb6247b3.zip | |
ARM: ensure initial page tables are setup for SMP systems
Mapping the same memory using two different attributes (memory
type, shareability, cacheability) is unpredictable. During boot,
we encounter a situation when we're updating the kernel's page
tables which can lead to dirty cache lines existing in the cache
which are subsequently missed. This causes stack corruption,
and therefore a crash.
Therefore, ensure that the shared and cacheability settings
matches the configuration that will be used later; this together
with the restriction in early_cachepolicy() ensures that we won't
create a mismatch during boot.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
| -rw-r--r-- | arch/arm/mm/mmu.c | 7 | ||||
| -rw-r--r-- | arch/arm/mm/proc-v6.S | 7 | ||||
| -rw-r--r-- | arch/arm/mm/proc-v7.S | 7 |
3 files changed, 15 insertions, 6 deletions
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index 02243eeccf50..ea67be0223ac 100644 --- a/arch/arm/mm/mmu.c +++ b/arch/arm/mm/mmu.c @@ -117,6 +117,13 @@ static void __init early_cachepolicy(char **p) } if (i == ARRAY_SIZE(cache_policies)) printk(KERN_ERR "ERROR: unknown or unsupported cache policy\n"); + /* + * This restriction is partly to do with the way we boot; it is + * unpredictable to have memory mapped using two different sets of + * memory attributes (shared, type, and cache attribs). We can not + * change these attributes once the initial assembly has setup the + * page tables. + */ if (cpu_architecture() >= CPU_ARCH_ARMv6) { printk(KERN_WARNING "Only cachepolicy=writeback supported on ARMv6 and later\n"); cachepolicy = CPOLICY_WRITEBACK; diff --git a/arch/arm/mm/proc-v6.S b/arch/arm/mm/proc-v6.S index 194737d60a22..70f75d2e3ead 100644 --- a/arch/arm/mm/proc-v6.S +++ b/arch/arm/mm/proc-v6.S @@ -32,8 +32,10 @@ #ifndef CONFIG_SMP #define TTB_FLAGS TTB_RGN_WBWA +#define PMD_FLAGS PMD_SECT_WB #else #define TTB_FLAGS TTB_RGN_WBWA|TTB_S +#define PMD_FLAGS PMD_SECT_WBWA|PMD_SECT_S #endif ENTRY(cpu_v6_proc_init) @@ -222,10 +224,9 @@ __v6_proc_info: .long 0x0007b000 .long 0x0007f000 .long PMD_TYPE_SECT | \ - PMD_SECT_BUFFERABLE | \ - PMD_SECT_CACHEABLE | \ PMD_SECT_AP_WRITE | \ - PMD_SECT_AP_READ + PMD_SECT_AP_READ | \ + PMD_FLAGS .long PMD_TYPE_SECT | \ PMD_SECT_XN | \ PMD_SECT_AP_WRITE | \ diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S index 23ebcf6eab9f..eeeed01ee44a 100644 --- a/arch/arm/mm/proc-v7.S +++ b/arch/arm/mm/proc-v7.S @@ -33,9 +33,11 @@ #ifndef CONFIG_SMP /* PTWs cacheable, inner WB not shareable, outer WB not shareable */ #define TTB_FLAGS TTB_IRGN_WB|TTB_RGN_OC_WB +#define PMD_FLAGS PMD_SECT_WB #else /* PTWs cacheable, inner WBWA shareable, outer WBWA not shareable */ #define TTB_FLAGS TTB_IRGN_WBWA|TTB_S|TTB_NOS|TTB_RGN_OC_WBWA +#define PMD_FLAGS PMD_SECT_WBWA|PMD_SECT_S #endif ENTRY(cpu_v7_proc_init) @@ -326,10 +328,9 @@ __v7_proc_info: .long 0x000f0000 @ Required ID value .long 0x000f0000 @ Mask for ID .long PMD_TYPE_SECT | \ - PMD_SECT_BUFFERABLE | \ - PMD_SECT_CACHEABLE | \ PMD_SECT_AP_WRITE | \ - PMD_SECT_AP_READ + PMD_SECT_AP_READ | \ + PMD_FLAGS .long PMD_TYPE_SECT | \ PMD_SECT_XN | \ PMD_SECT_AP_WRITE | \ |