diff options
Diffstat (limited to 'arch/arm/kernel/signal.c')
| -rw-r--r-- | arch/arm/kernel/signal.c | 52 |
1 files changed, 45 insertions, 7 deletions
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c index 1c16c35c271..0f17e06d51e 100644 --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -8,6 +8,7 @@ * published by the Free Software Foundation. */ #include <linux/errno.h> +#include <linux/random.h> #include <linux/signal.h> #include <linux/personality.h> #include <linux/uaccess.h> @@ -15,12 +16,11 @@ #include <asm/elf.h> #include <asm/cacheflush.h> +#include <asm/traps.h> #include <asm/ucontext.h> #include <asm/unistd.h> #include <asm/vfp.h> -#include "signal.h" - /* * For ARM syscalls, we encode the syscall number into the instruction. */ @@ -40,11 +40,13 @@ #define SWI_THUMB_SIGRETURN (0xdf00 << 16 | 0x2700 | (__NR_sigreturn - __NR_SYSCALL_BASE)) #define SWI_THUMB_RT_SIGRETURN (0xdf00 << 16 | 0x2700 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE)) -const unsigned long sigreturn_codes[7] = { +static const unsigned long sigreturn_codes[7] = { MOV_R7_NR_SIGRETURN, SWI_SYS_SIGRETURN, SWI_THUMB_SIGRETURN, MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN, }; +static unsigned long signal_return_offset; + #ifdef CONFIG_CRUNCH static int preserve_crunch_context(struct crunch_sigframe __user *frame) { @@ -401,12 +403,15 @@ setup_return(struct pt_regs *regs, struct ksignal *ksig, return 1; if ((cpsr & MODE32_BIT) && !IS_ENABLED(CONFIG_ARM_MPU)) { + struct mm_struct *mm = current->mm; + /* - * 32-bit code can use the new high-page - * signal return code support except when the MPU has - * protected the vectors page from PL0 + * 32-bit code can use the signal return page + * except when the MPU has protected the vectors + * page from PL0 */ - retcode = KERN_SIGRETURN_CODE + (idx << 2) + thumb; + retcode = mm->context.sigpage + signal_return_offset + + (idx << 2) + thumb; } else { /* * Ensure that the instruction cache sees @@ -608,3 +613,36 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall) } while (thread_flags & _TIF_WORK_MASK); return 0; } + +static struct page *signal_page; + +struct page *get_signal_page(void) +{ + if (!signal_page) { + unsigned long ptr; + unsigned offset; + void *addr; + + signal_page = alloc_pages(GFP_KERNEL, 0); + + if (!signal_page) + return NULL; + + addr = page_address(signal_page); + + /* Give the signal return code some randomness */ + offset = 0x200 + (get_random_int() & 0x7fc); + signal_return_offset = offset; + + /* + * Copy signal return handlers into the vector page, and + * set sigreturn to be a pointer to these. + */ + memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes)); + + ptr = (unsigned long)addr + offset; + flush_icache_range(ptr, ptr + sizeof(sigreturn_codes)); + } + + return signal_page; +} |