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/kernel/traps.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) (limited to 'arch/arm/kernel/traps.c') diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c index cda78d59aa31..87abca018054 100644 --- a/arch/arm/kernel/traps.c +++ b/arch/arm/kernel/traps.c @@ -37,6 +37,8 @@ static const char *handler[]= { "prefetch abort", "data abort", "address exception", "interrupt" }; +void *vectors_page; + #ifdef CONFIG_DEBUG_USER unsigned int user_debug; @@ -759,7 +761,11 @@ static void __init kuser_get_tls_init(unsigned long vectors) void __init early_trap_init(void) { +#if defined(CONFIG_CPU_USE_DOMAINS) unsigned long vectors = CONFIG_VECTORS_BASE; +#else + unsigned long vectors = (unsigned long)vectors_page; +#endif extern char __stubs_start[], __stubs_end[]; extern char __vectors_start[], __vectors_end[]; extern char __kuser_helper_start[], __kuser_helper_end[]; @@ -783,10 +789,10 @@ void __init early_trap_init(void) * Copy signal return handlers into the vector page, and * set sigreturn to be a pointer to these. */ - memcpy((void *)KERN_SIGRETURN_CODE, sigreturn_codes, - sizeof(sigreturn_codes)); - memcpy((void *)KERN_RESTART_CODE, syscall_restart_code, - sizeof(syscall_restart_code)); + memcpy((void *)(vectors + KERN_SIGRETURN_CODE - CONFIG_VECTORS_BASE), + sigreturn_codes, sizeof(sigreturn_codes)); + memcpy((void *)(vectors + KERN_RESTART_CODE - CONFIG_VECTORS_BASE), + syscall_restart_code, sizeof(syscall_restart_code)); flush_icache_range(vectors, vectors + PAGE_SIZE); modify_domain(DOMAIN_USER, DOMAIN_CLIENT); -- cgit v1.2.3