Commit f606a6ff authored by Nicolas Pitre's avatar Nicolas Pitre Committed by Russell King
Browse files

[ARM] 3626/1: ARM EABI: fix syscall restarting 



Patch from Nicolas Pitre

The RESTARTBLOCK case currently store some code on the stack to invoke
sys_restart_syscall.  However this is ABI dependent and there is a
mismatch with the way __NR_restart_syscall gets defined when the kernel
is compiled for EABI.

There is also a long standing bug in the thumb case since with OABI the
__NR_restart_syscall value includes __NR_SYSCALL_BASE which should not
be the case for Thumb syscalls.

Credits to Yauheni Kaliuta <yauheni.kaliuta@gmail.com> for finding the
EABI bug.

Signed-off-by: default avatarNicolas Pitre <nico@cam.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 92b7eb8f

arch/arm/kernel/signal.c

+19 −2
Original line number Diff line number Diff line
@@ -665,17 +665,33 @@ static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall) 
	if (syscall) {

		if (regs->ARM_r0 == -ERESTART_RESTARTBLOCK) {

			if (thumb_mode(regs)) {

				regs->ARM_r7 = __NR_restart_syscall;

				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;

				u32 swival = __NR_restart_syscall;



				regs->ARM_sp -= 12;

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



				/*

				 * Either we supports 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.

				 */

				swival = swival - __NR_SYSCAll_BASE + __NR_OABI_SYSCALL_BASE;



				put_user(regs->ARM_pc, &usp[0]);

				/* swi __NR_restart_syscall */

				put_user(0xef000000 | __NR_restart_syscall, &usp[1]);

				put_user(0xef000000 | swival, &usp[1]);

				/* ldr	pc, [sp], #12 */

				put_user(0xe49df00c, &usp[2]);
@@ -683,6 +699,7 @@ static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall) 
						   (unsigned long)(usp + 3));



				regs->ARM_pc = regs->ARM_sp + 4;

#endif

			}

		}

		if (regs->ARM_r0 == -ERESTARTNOHAND ||

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