From 247055aa21ffef1c49dd64710d5e94c2aee19b58 Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Mon, 13 Sep 2010 16:03:21 +0100 Subject: ARM: 6384/1: Remove the domain switching on ARMv6k/v7 CPUs This patch removes the domain switching functionality via the set_fs and __switch_to functions on cores that have a TLS register. Currently, the ioremap and vmalloc areas share the same level 1 page tables and therefore have the same domain (DOMAIN_KERNEL). When the kernel domain is modified from Client to Manager (via the __set_fs or in the __switch_to function), the XN (eXecute Never) bit is overridden and newer CPUs can speculatively prefetch the ioremap'ed memory. Linux performs the kernel domain switching to allow user-specific functions (copy_to/from_user, get/put_user etc.) to access kernel memory. In order for these functions to work with the kernel domain set to Client, the patch modifies the LDRT/STRT and related instructions to the LDR/STR ones. The user pages access rights are also modified for kernel read-only access rather than read/write so that the copy-on-write mechanism still works. CPU_USE_DOMAINS gets disabled only if the hardware has a TLS register (CPU_32v6K is defined) since writing the TLS value to the high vectors page isn't possible. The user addresses passed to the kernel are checked by the access_ok() function so that they do not point to the kernel space. Tested-by: Anton Vorontsov Cc: Tony Lindgren Signed-off-by: Catalin Marinas Signed-off-by: Russell King --- arch/arm/include/asm/traps.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/arm/include/asm/traps.h') diff --git a/arch/arm/include/asm/traps.h b/arch/arm/include/asm/traps.h index 491960bf4260..af5d5d1388c6 100644 --- a/arch/arm/include/asm/traps.h +++ b/arch/arm/include/asm/traps.h @@ -27,4 +27,6 @@ static inline int in_exception_text(unsigned long ptr) extern void __init early_trap_init(void); extern void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame); +extern void *vectors_page; + #endif -- cgit