From 2324f8a281c84b19aef7251cde4df51876328d42 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 7 Feb 2014 19:12:27 +0100 Subject: ARM: 7954/1: mm: remove remaining domain support from ARMv6 commit b6ccb9803e90c16b212cf4ed62913a7591e79a39 upstream. CPU_32v6 currently selects CPU_USE_DOMAINS if CPU_V6 and MMU. This is because ARM 1136 r0pX CPUs lack the v6k extensions, and therefore do not have hardware thread registers. The lack of these registers requires the kernel to update the vectors page at each context switch in order to write a new TLS pointer. This write must be done via the userspace mapping, since aliasing caches can lead to expensive flushing when using kmap. Finally, this requires the vectors page to be mapped r/w for kernel and r/o for user, which has implications for things like put_user which must trigger CoW appropriately when targetting user pages. The upshot of all this is that a v6/v7 kernel makes use of domains to segregate kernel and user memory accesses. This has the nasty side-effect of making device mappings executable, which has been observed to cause subtle bugs on recent cores (e.g. Cortex-A15 performing a speculative instruction fetch from the GIC and acking an interrupt in the process). This patch solves this problem by removing the remaining domain support from ARMv6. A new memory type is added specifically for the vectors page which allows that page (and only that page) to be mapped as user r/o, kernel r/w. All other user r/o pages are mapped also as kernel r/o. Patch co-developed with Russell King. Signed-off-by: Will Deacon Signed-off-by: Russell King [bwh: Backported to 3.2: - Adjust filename, context - Drop condition on CONFIG_ARM_LPAE] Signed-off-by: Ben Hutchings --- arch/arm/include/asm/futex.h | 6 ------ arch/arm/include/asm/pgtable-2level.h | 1 + arch/arm/mm/Kconfig | 3 +-- arch/arm/mm/mmu.c | 8 ++++++++ arch/arm/mm/proc-macros.S | 19 ++++++------------- arch/arm/mm/proc-v7.S | 7 ------- 6 files changed, 16 insertions(+), 28 deletions(-) diff --git a/arch/arm/include/asm/futex.h b/arch/arm/include/asm/futex.h index 253cc86318bf..aefd4594c9bf 100644 --- a/arch/arm/include/asm/futex.h +++ b/arch/arm/include/asm/futex.h @@ -3,11 +3,6 @@ #ifdef __KERNEL__ -#if defined(CONFIG_CPU_USE_DOMAINS) && defined(CONFIG_SMP) -/* ARM doesn't provide unprivileged exclusive memory accessors */ -#include -#else - #include #include #include @@ -163,6 +158,5 @@ futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr) return ret; } -#endif /* !(CPU_USE_DOMAINS && SMP) */ #endif /* __KERNEL__ */ #endif /* _ASM_ARM_FUTEX_H */ diff --git a/arch/arm/include/asm/pgtable-2level.h b/arch/arm/include/asm/pgtable-2level.h index cd7e6272a226..1cb80c4627e4 100644 --- a/arch/arm/include/asm/pgtable-2level.h +++ b/arch/arm/include/asm/pgtable-2level.h @@ -139,6 +139,7 @@ #define L_PTE_MT_DEV_NONSHARED (_AT(pteval_t, 0x0c) << 2) /* 1100 */ #define L_PTE_MT_DEV_WC (_AT(pteval_t, 0x09) << 2) /* 1001 */ #define L_PTE_MT_DEV_CACHED (_AT(pteval_t, 0x0b) << 2) /* 1011 */ +#define L_PTE_MT_VECTORS (_AT(pteval_t, 0x0f) << 2) /* 1111 */ #define L_PTE_MT_MASK (_AT(pteval_t, 0x0f) << 2) #endif /* _ASM_PGTABLE_2LEVEL_H */ diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig index 67f75a0b66d6..4e1ef6edb489 100644 --- a/arch/arm/mm/Kconfig +++ b/arch/arm/mm/Kconfig @@ -458,7 +458,6 @@ config CPU_32v5 config CPU_32v6 bool select TLS_REG_EMUL if !CPU_32v6K && !MMU - select CPU_USE_DOMAINS if CPU_V6 && MMU config CPU_32v6K bool @@ -652,7 +651,7 @@ config ARM_THUMBEE config SWP_EMULATE bool "Emulate SWP/SWPB instructions" - depends on !CPU_USE_DOMAINS && CPU_V7 + depends on CPU_V7 select HAVE_PROC_CPU if PROC_FS default y if SMP help diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index 9e28fdb1c739..082fa18b2583 100644 --- a/arch/arm/mm/mmu.c +++ b/arch/arm/mm/mmu.c @@ -425,6 +425,14 @@ static void __init build_mem_type_table(void) mem_types[MT_MEMORY_NONCACHED].prot_sect |= PMD_SECT_S; mem_types[MT_MEMORY_NONCACHED].prot_pte |= L_PTE_SHARED; } + /* + * We don't use domains on ARMv6 (since this causes problems with + * v6/v7 kernels), so we must use a separate memory type for user + * r/o, kernel r/w to map the vectors page. + */ + if (cpu_arch == CPU_ARCH_ARMv6) + vecs_pgprot |= L_PTE_MT_VECTORS; + /* * ARMv6 and above have extended page tables. */ diff --git a/arch/arm/mm/proc-macros.S b/arch/arm/mm/proc-macros.S index 29a6021a4fd9..8a3edd4a3e48 100644 --- a/arch/arm/mm/proc-macros.S +++ b/arch/arm/mm/proc-macros.S @@ -106,13 +106,9 @@ * 100x 1 0 1 r/o no acc * 10x0 1 0 1 r/o no acc * 1011 0 0 1 r/w no acc - * 110x 0 1 0 r/w r/o - * 11x0 0 1 0 r/w r/o - * 1111 0 1 1 r/w r/w - * - * If !CONFIG_CPU_USE_DOMAINS, the following permissions are changed: * 110x 1 1 1 r/o r/o * 11x0 1 1 1 r/o r/o + * 1111 0 1 1 r/w r/w */ .macro armv6_mt_table pfx \pfx\()_mt_table: @@ -131,7 +127,7 @@ .long PTE_EXT_TEX(2) @ L_PTE_MT_DEV_NONSHARED .long 0x00 @ unused .long 0x00 @ unused - .long 0x00 @ unused + .long PTE_CACHEABLE | PTE_BUFFERABLE | PTE_EXT_APX @ L_PTE_MT_VECTORS .endm .macro armv6_set_pte_ext pfx @@ -152,24 +148,21 @@ tst r1, #L_PTE_USER orrne r3, r3, #PTE_EXT_AP1 -#ifdef CONFIG_CPU_USE_DOMAINS - @ allow kernel read/write access to read-only user pages tstne r3, #PTE_EXT_APX - bicne r3, r3, #PTE_EXT_APX | PTE_EXT_AP0 -#endif + + @ user read-only -> kernel read-only + bicne r3, r3, #PTE_EXT_AP0 tst r1, #L_PTE_XN orrne r3, r3, #PTE_EXT_XN - orr r3, r3, r2 + eor r3, r3, r2 tst r1, #L_PTE_YOUNG tstne r1, #L_PTE_PRESENT moveq r3, #0 -#ifndef CONFIG_CPU_USE_DOMAINS tstne r1, #L_PTE_NONE movne r3, #0 -#endif str r3, [r0] mcr p15, 0, r0, c7, c10, 1 @ flush_pte diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S index 21b09f2605c4..43c69815de69 100644 --- a/arch/arm/mm/proc-v7.S +++ b/arch/arm/mm/proc-v7.S @@ -160,21 +160,14 @@ ENTRY(cpu_v7_set_pte_ext) tst r1, #L_PTE_USER orrne r3, r3, #PTE_EXT_AP1 -#ifdef CONFIG_CPU_USE_DOMAINS - @ allow kernel read/write access to read-only user pages - tstne r3, #PTE_EXT_APX - bicne r3, r3, #PTE_EXT_APX | PTE_EXT_AP0 -#endif tst r1, #L_PTE_XN orrne r3, r3, #PTE_EXT_XN tst r1, #L_PTE_YOUNG tstne r1, #L_PTE_PRESENT -#ifndef CONFIG_CPU_USE_DOMAINS eorne r1, r1, #L_PTE_NONE tstne r1, #L_PTE_NONE -#endif moveq r3, #0 ARM( str r3, [r0, #2048]! ) -- cgit v1.2.3