Merge "ARM: move signal handlers into a vdso-like page" (99bd4e41) · Commits · e / devices / android_kernel_sony_msm8994

arch/arm/include/asm/elf.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -130,4 +130,8 @@ struct mm_struct;
		extern unsigned long arch_randomize_brk(struct mm_struct *mm);
		#define arch_randomize_brk arch_randomize_brk

		#define ARCH_HAS_SETUP_ADDITIONAL_PAGES 1
		struct linux_binprm;
		int arch_setup_additional_pages(struct linux_binprm *, int);

		#endif

arch/arm/include/asm/mmu.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -8,6 +8,7 @@ typedef struct {
		atomic64_t id;
		#endif
		unsigned int vmalloc_seq;
		unsigned long sigpage;
		} mm_context_t;

		#ifdef CONFIG_CPU_HAS_ASID

arch/arm/kernel/process.c

+36 −2

Original line number	Diff line number	Diff line
		@@ -568,8 +568,8 @@ unsigned long arch_randomize_brk(struct mm_struct *mm)
		#ifdef CONFIG_MMU
		/*
		* The vectors page is always readable from user space for the
		* atomic helpers and the signal restart code. Insert it into the
		* gate_vma so that it is visible through ptrace and /proc/<pid>/mem.
		* atomic helpers. Insert it into the gate_vma so that it is visible
		* through ptrace and /proc/<pid>/mem.
		*/
		static struct vm_area_struct gate_vma = {
		.vm_start = 0xffff0000,
		@@ -603,9 +603,43 @@ const char arch_vma_name(struct vm_area_struct vma)
		{
		if (vma == &gate_vma)
		return "[vectors]";
		else if (vma->vm_mm && vma->vm_start == vma->vm_mm->context.sigpage)
		return "[sigpage]";
		else if (vma == get_user_timers_vma(NULL))
		return "[timers]";
		else
		return NULL;
		}

		extern struct page *get_signal_page(void);

		int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
		{
		struct mm_struct *mm = current->mm;
		struct page *page;
		unsigned long addr;
		int ret;

		page = get_signal_page();
		if (!page)
		return -ENOMEM;

		down_write(&mm->mmap_sem);
		addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
		if (IS_ERR_VALUE(addr)) {
		ret = addr;
		goto up_fail;
		}

		ret = install_special_mapping(mm, addr, PAGE_SIZE,
		VM_READ \| VM_EXEC \| VM_MAYREAD \| VM_MAYWRITE \| VM_MAYEXEC,
		&page);

		if (ret == 0)
		mm->context.sigpage = addr;

		up_fail:
		up_write(&mm->mmap_sem);
		return ret;
		}
		#endif

arch/arm/kernel/signal.c

+45 −6

Original line number	Diff line number	Diff line
		@@ -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)
		{
		@@ -397,11 +399,15 @@ setup_return(struct pt_regs regs, struct ksignal ksig,
		return 1;

		if (cpsr & MODE32_BIT) {
		struct mm_struct *mm = current->mm;

		/*
		* 32-bit code can use the new high-page
		* signal return code support.
		* 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
		@@ -603,3 +609,36 @@ 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;
		}

arch/arm/kernel/signal.h

deleted100644 → 0

+0 −12

Original line number	Diff line number	Diff line
		/*
		* linux/arch/arm/kernel/signal.h
		*
		* Copyright (C) 2005-2009 Russell King.
		*
		* This program is free software; you can redistribute it and/or modify
		* it under the terms of the GNU General Public License version 2 as
		* published by the Free Software Foundation.
		*/
		#define KERN_SIGRETURN_CODE (CONFIG_VECTORS_BASE + 0x00000500)

		extern const unsigned long sigreturn_codes[7];