diff options
| author | Catalin Marinas <catalin.marinas@arm.com> | 2016-07-01 16:53:00 +0100 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2016-11-21 18:48:53 +0000 |
| commit | 4b65a5db362783ab4b04ca1c1d2ad70ed9b0ba2a (patch) | |
| tree | 56196f2fa7dbe5a41061b1aed297704ef7e2bbea /arch/arm64/kernel | |
| parent | f33bcf03e6079668da6bf4eec4a7dcf9289131d0 (diff) | |
arm64: Introduce uaccess_{disable,enable} functionality based on TTBR0_EL1
This patch adds the uaccess macros/functions to disable access to user
space by setting TTBR0_EL1 to a reserved zeroed page. Since the value
written to TTBR0_EL1 must be a physical address, for simplicity this
patch introduces a reserved_ttbr0 page at a constant offset from
swapper_pg_dir. The uaccess_disable code uses the ttbr1_el1 value
adjusted by the reserved_ttbr0 offset.
Enabling access to user is done by restoring TTBR0_EL1 with the value
from the struct thread_info ttbr0 variable. Interrupts must be disabled
during the uaccess_ttbr0_enable code to ensure the atomicity of the
thread_info.ttbr0 read and TTBR0_EL1 write. This patch also moves the
get_thread_info asm macro from entry.S to assembler.h for reuse in the
uaccess_ttbr0_* macros.
Cc: Will Deacon <will.deacon@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel')
| -rw-r--r-- | arch/arm64/kernel/asm-offsets.c | 3 | ||||
| -rw-r--r-- | arch/arm64/kernel/cpufeature.c | 1 | ||||
| -rw-r--r-- | arch/arm64/kernel/entry.S | 4 | ||||
| -rw-r--r-- | arch/arm64/kernel/head.S | 6 | ||||
| -rw-r--r-- | arch/arm64/kernel/vmlinux.lds.S | 5 |
5 files changed, 12 insertions, 7 deletions
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c index c2dc9fa4f09b..bc049afc73a7 100644 --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -39,6 +39,9 @@ int main(void) DEFINE(TSK_TI_FLAGS, offsetof(struct task_struct, thread_info.flags)); DEFINE(TSK_TI_PREEMPT, offsetof(struct task_struct, thread_info.preempt_count)); DEFINE(TSK_TI_ADDR_LIMIT, offsetof(struct task_struct, thread_info.addr_limit)); +#ifdef CONFIG_ARM64_SW_TTBR0_PAN + DEFINE(TSK_TI_TTBR0, offsetof(struct task_struct, thread_info.ttbr0)); +#endif DEFINE(TSK_STACK, offsetof(struct task_struct, stack)); BLANK(); DEFINE(THREAD_CPU_CONTEXT, offsetof(struct task_struct, thread.cpu_context)); diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index f89385d794f6..fdf8f045929f 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -47,6 +47,7 @@ unsigned int compat_elf_hwcap2 __read_mostly; #endif DECLARE_BITMAP(cpu_hwcaps, ARM64_NCAPS); +EXPORT_SYMBOL(cpu_hwcaps); DEFINE_STATIC_KEY_ARRAY_FALSE(cpu_hwcap_keys, ARM64_NCAPS); EXPORT_SYMBOL(cpu_hwcap_keys); diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 6349a8324b4f..b7db3766a312 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -183,10 +183,6 @@ alternative_else_nop_endif eret // return to kernel .endm - .macro get_thread_info, rd - mrs \rd, sp_el0 - .endm - .macro irq_stack_entry mov x19, sp // preserve the original sp diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index eaafb253bbfa..7ee6d74101cf 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -326,14 +326,14 @@ __create_page_tables: * dirty cache lines being evicted. */ adrp x0, idmap_pg_dir - adrp x1, swapper_pg_dir + SWAPPER_DIR_SIZE + adrp x1, swapper_pg_dir + SWAPPER_DIR_SIZE + RESERVED_TTBR0_SIZE bl __inval_cache_range /* * Clear the idmap and swapper page tables. */ adrp x0, idmap_pg_dir - adrp x6, swapper_pg_dir + SWAPPER_DIR_SIZE + adrp x6, swapper_pg_dir + SWAPPER_DIR_SIZE + RESERVED_TTBR0_SIZE 1: stp xzr, xzr, [x0], #16 stp xzr, xzr, [x0], #16 stp xzr, xzr, [x0], #16 @@ -412,7 +412,7 @@ __create_page_tables: * tables again to remove any speculatively loaded cache lines. */ adrp x0, idmap_pg_dir - adrp x1, swapper_pg_dir + SWAPPER_DIR_SIZE + adrp x1, swapper_pg_dir + SWAPPER_DIR_SIZE + RESERVED_TTBR0_SIZE dmb sy bl __inval_cache_range diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index 1105aab1e6d6..b8deffa9e1bf 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -216,6 +216,11 @@ SECTIONS swapper_pg_dir = .; . += SWAPPER_DIR_SIZE; +#ifdef CONFIG_ARM64_SW_TTBR0_PAN + reserved_ttbr0 = .; + . += RESERVED_TTBR0_SIZE; +#endif + _end = .; STABS_DEBUG |