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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>
hifive-unleashed-5.1
Russell King 2009-11-01 17:44:24 +00:00
parent 6603a4fd51
commit 4b46d64165
3 changed files with 15 additions and 6 deletions
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7
arch/arm/mm/mmu.c
View File

@ -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;

7
arch/arm/mm/proc-v6.S
View File

@ -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 | \

7
arch/arm/mm/proc-v7.S
View File

@ -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 | \