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Commit 02a6ec6a authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'audit' of git://git.linaro.org/people/rmk/linux-arm 

Pull ARM audit/signal updates from Russell King:
 "ARM audit/signal handling updates from Al and Will.  This improves on
  the work Viro did last merge window, and sorts out some of the issues
  found with that work."

* 'audit' of git://git.linaro.org/people/rmk/linux-arm:
  ARM: 7475/1: sys_trace: allow all syscall arguments to be updated via ptrace
  ARM: 7474/1: get rid of TIF_SYSCALL_RESTARTSYS
  ARM: 7473/1: deal with handlerless restarts without leaving the kernel
  ARM: 7472/1: pull all work_pending logics into C function
  ARM: 7471/1: Revert "7442/1: Revert "remove unused restart trampoline""
  ARM: 7470/1: Revert "7443/1: Revert "new way of handling ERESTART_RESTARTBLOCK""
parents 9a2533c3 c7aa00db

arch/arm/kernel/entry-common.S

+9 −15
Original line number Diff line number Diff line
@@ -51,23 +51,15 @@ ret_fast_syscall: 
fast_work_pending:

	str	r0, [sp, #S_R0+S_OFF]!		@ returned r0

work_pending:

	tst	r1, #_TIF_NEED_RESCHED

	bne	work_resched

	/*

	 * TIF_SIGPENDING or TIF_NOTIFY_RESUME must've been set if we got here

	 */

	ldr	r2, [sp, #S_PSR]

	mov	r0, sp				@ 'regs'

	tst	r2, #15				@ are we returning to user mode?

	bne	no_work_pending			@ no?  just leave, then...

	mov	r2, why				@ 'syscall'

	tst	r1, #_TIF_SIGPENDING		@ delivering a signal?

	movne	why, #0				@ prevent further restarts

	bl	do_notify_resume

	b	ret_slow_syscall		@ Check work again

	bl	do_work_pending

	cmp	r0, #0

	beq	no_work_pending

	movlt	scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)

	ldmia	sp, {r0 - r6}			@ have to reload r0 - r6

	b	local_restart			@ ... and off we go



work_resched:

	bl	schedule

/*

 * "slow" syscall return path.  "why" tells us if this was a real syscall.

 */
@@ -409,6 +401,7 @@ ENTRY(vector_swi) 
	eor	scno, scno, #__NR_SYSCALL_BASE	@ check OS number

#endif



local_restart:

	ldr	r10, [tsk, #TI_FLAGS]		@ check for syscall tracing

	stmdb	sp!, {r4, r5}			@ push fifth and sixth args
@@ -450,7 +443,8 @@ __sys_trace: 
	mov	scno, r0			@ syscall number (possibly new)

	add	r1, sp, #S_R0 + S_OFF		@ pointer to regs

	cmp	scno, #NR_syscalls		@ check upper syscall limit

	ldmccia	r1, {r0 - r3}			@ have to reload r0 - r3

	ldmccia	r1, {r0 - r6}			@ have to reload r0 - r6

	stmccia	sp, {r4, r5}			@ and update the stack args

	ldrcc	pc, [tbl, scno, lsl #2]		@ call sys_* routine

	b	2b

arch/arm/kernel/ptrace.c

+1 −0
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ 
#include <linux/regset.h>

#include <linux/audit.h>

#include <linux/tracehook.h>

#include <linux/unistd.h>



#include <asm/pgtable.h>

#include <asm/traps.h>

arch/arm/kernel/signal.c

+48 −66
Original line number Diff line number Diff line
@@ -27,7 +27,6 @@ 
 */

#define SWI_SYS_SIGRETURN	(0xef000000|(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE))

#define SWI_SYS_RT_SIGRETURN	(0xef000000|(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE))

#define SWI_SYS_RESTART		(0xef000000|__NR_restart_syscall|__NR_OABI_SYSCALL_BASE)



/*

 * With EABI, the syscall number has to be loaded into r7.
@@ -47,18 +46,6 @@ const unsigned long sigreturn_codes[7] = { 
	MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN,

};



/*

 * Either we support OABI only, or we have EABI with the OABI

 * compat layer enabled.  In the later case we don't know if

 * user space is EABI or not, and if not we must not clobber r7.

 * Always using the OABI syscall solves that issue and works for

 * all those cases.

 */

const unsigned long syscall_restart_code[2] = {

	SWI_SYS_RESTART,	/* swi	__NR_restart_syscall */

	0xe49df004,		/* ldr	pc, [sp], #4 */

};



/*

 * atomically swap in the new signal mask, and wait for a signal.

 */
@@ -582,12 +569,13 @@ handle_signal(unsigned long sig, struct k_sigaction *ka, 
 * the kernel can handle, and then we build all the user-level signal handling

 * stack-frames in one go after that.

 */

static void do_signal(struct pt_regs *regs, int syscall)

static int do_signal(struct pt_regs *regs, int syscall)

{

	unsigned int retval = 0, continue_addr = 0, restart_addr = 0;

	struct k_sigaction ka;

	siginfo_t info;

	int signr;

	int restart = 0;



	/*

	 * If we were from a system call, check for system call restarting...
@@ -602,15 +590,15 @@ static void do_signal(struct pt_regs *regs, int syscall) 
		 * debugger will see the already changed PSW.

		 */

		switch (retval) {

		case -ERESTART_RESTARTBLOCK:

			restart -= 2;

		case -ERESTARTNOHAND:

		case -ERESTARTSYS:

		case -ERESTARTNOINTR:

			restart++;

			regs->ARM_r0 = regs->ARM_ORIG_r0;

			regs->ARM_pc = restart_addr;

			break;

		case -ERESTART_RESTARTBLOCK:

			regs->ARM_r0 = -EINTR;

			break;

		}

	}
@@ -619,14 +607,17 @@ static void do_signal(struct pt_regs *regs, int syscall) 
	 * point the debugger may change all our registers ...

	 */

	signr = get_signal_to_deliver(&info, &ka, regs, NULL);

	if (signr > 0) {

	/*

	 * Depending on the signal settings we may need to revert the

	 * decision to restart the system call.  But skip this if a

	 * debugger has chosen to restart at a different PC.

	 */

		if (regs->ARM_pc == restart_addr) {

			if (retval == -ERESTARTNOHAND

	if (regs->ARM_pc != restart_addr)

		restart = 0;

	if (signr > 0) {

		if (unlikely(restart)) {

			if (retval == -ERESTARTNOHAND ||

			    retval == -ERESTART_RESTARTBLOCK

			    || (retval == -ERESTARTSYS

				&& !(ka.sa.sa_flags & SA_RESTART))) {

				regs->ARM_r0 = -EINTR;
@@ -635,52 +626,43 @@ static void do_signal(struct pt_regs *regs, int syscall) 
		}



		handle_signal(signr, &ka, &info, regs);

		return;

	}



	if (syscall) {

		/*

		 * Handle restarting a different system call.  As above,

		 * if a debugger has chosen to restart at a different PC,

		 * ignore the restart.

		 */

		if (retval == -ERESTART_RESTARTBLOCK

		    && regs->ARM_pc == continue_addr) {

			if (thumb_mode(regs)) {

				regs->ARM_r7 = __NR_restart_syscall - __NR_SYSCALL_BASE;

				regs->ARM_pc -= 2;

			} else {

#if defined(CONFIG_AEABI) && !defined(CONFIG_OABI_COMPAT)

				regs->ARM_r7 = __NR_restart_syscall;

				regs->ARM_pc -= 4;

#else

				u32 __user *usp;



				regs->ARM_sp -= 4;

				usp = (u32 __user *)regs->ARM_sp;



				if (put_user(regs->ARM_pc, usp) == 0) {

					regs->ARM_pc = KERN_RESTART_CODE;

				} else {

					regs->ARM_sp += 4;

					force_sigsegv(0, current);

				}

#endif

			}

		}

		return 0;

	}



	restore_saved_sigmask();

	if (unlikely(restart))

		regs->ARM_pc = continue_addr;

	return restart;

}



asmlinkage void

do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall)

asmlinkage int

do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)

{

	if (thread_flags & _TIF_SIGPENDING)

		do_signal(regs, syscall);



	if (thread_flags & _TIF_NOTIFY_RESUME) {

	do {

		if (likely(thread_flags & _TIF_NEED_RESCHED)) {

			schedule();

		} else {

			if (unlikely(!user_mode(regs)))

				return 0;

			local_irq_enable();

			if (thread_flags & _TIF_SIGPENDING) {

				int restart = do_signal(regs, syscall);

				if (unlikely(restart)) {

					/*

					 * Restart without handlers.

					 * Deal with it without leaving

					 * the kernel space.

					 */

					return restart;

				}

				syscall = 0;

			} else {

				clear_thread_flag(TIF_NOTIFY_RESUME);

				tracehook_notify_resume(regs);

			}

		}

		local_irq_disable();

		thread_flags = current_thread_info()->flags;

	} while (thread_flags & _TIF_WORK_MASK);

	return 0;

}

arch/arm/kernel/signal.h

+0 −2
Original line number Diff line number Diff line
@@ -8,7 +8,5 @@ 
 * published by the Free Software Foundation.

 */

#define KERN_SIGRETURN_CODE	(CONFIG_VECTORS_BASE + 0x00000500)

#define KERN_RESTART_CODE	(KERN_SIGRETURN_CODE + sizeof(sigreturn_codes))



extern const unsigned long sigreturn_codes[7];
 
extern const unsigned long syscall_restart_code[2];

arch/arm/kernel/traps.c

+0 −2
Original line number Diff line number Diff line
@@ -844,8 +844,6 @@ void __init early_trap_init(void *vectors_base) 
	 */

	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);