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Commit de419840 authored by Jon Medhurst's avatar Jon Medhurst Committed by Tixy
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ARM: kprobes: Make kprobes framework work on Thumb-2 kernels 



Fix up kprobes framework so that it builds and correctly interworks on
Thumb-2 kernels.

Signed-off-by: default avatarJon Medhurst <tixy@yxit.co.uk>
Acked-by: default avatarNicolas Pitre <nicolas.pitre@linaro.org>
parent aea49029

arch/arm/kernel/kprobes.c

+35 −2
Original line number Diff line number Diff line
@@ -302,7 +302,11 @@ void __naked __kprobes kretprobe_trampoline(void) 
		"bl	trampoline_handler	\n\t"

		"mov	lr, r0			\n\t"

		"ldmia	sp!, {r0 - r11}		\n\t"

#ifdef CONFIG_THUMB2_KERNEL

		"bx	lr			\n\t"

#else

		"mov	pc, lr			\n\t"

#endif

		: : : "memory");

}
@@ -380,11 +384,22 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) 
	struct jprobe *jp = container_of(p, struct jprobe, kp);

	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();

	long sp_addr = regs->ARM_sp;

	long cpsr;



	kcb->jprobe_saved_regs = *regs;

	memcpy(kcb->jprobes_stack, (void *)sp_addr, MIN_STACK_SIZE(sp_addr));

	regs->ARM_pc = (long)jp->entry;

	regs->ARM_cpsr |= PSR_I_BIT;



	cpsr = regs->ARM_cpsr | PSR_I_BIT;

#ifdef CONFIG_THUMB2_KERNEL

	/* Set correct Thumb state in cpsr */

	if (regs->ARM_pc & 1)

		cpsr |= PSR_T_BIT;

	else

		cpsr &= ~PSR_T_BIT;

#endif

	regs->ARM_cpsr = cpsr;



	preempt_disable();

	return 1;

}
@@ -406,7 +421,12 @@ void __kprobes jprobe_return(void) 
		 * This is to prevent any simulated instruction from writing

		 * over the regs when they are accessing the stack.

		 */

#ifdef CONFIG_THUMB2_KERNEL

		"sub    r0, %0, %1		\n\t"

		"mov    sp, r0			\n\t"

#else

		"sub    sp, %0, %1		\n\t"

#endif

		"ldr    r0, ="__stringify(JPROBE_MAGIC_ADDR)"\n\t"

		"str    %0, [sp, %2]		\n\t"

		"str    r0, [sp, %3]		\n\t"
@@ -417,15 +437,28 @@ void __kprobes jprobe_return(void) 
		 * Return to the context saved by setjmp_pre_handler

		 * and restored by longjmp_break_handler.

		 */

#ifdef CONFIG_THUMB2_KERNEL

		"ldr	lr, [sp, %2]		\n\t" /* lr = saved sp */

		"ldrd	r0, r1, [sp, %5]	\n\t" /* r0,r1 = saved lr,pc */

		"ldr	r2, [sp, %4]		\n\t" /* r2 = saved psr */

		"stmdb	lr!, {r0, r1, r2}	\n\t" /* push saved lr and */

						      /* rfe context */

		"ldmia	sp, {r0 - r12}		\n\t"

		"mov	sp, lr			\n\t"

		"ldr	lr, [sp], #4		\n\t"

		"rfeia	sp!			\n\t"

#else

		"ldr	r0, [sp, %4]		\n\t"

		"msr	cpsr_cxsf, r0		\n\t"

		"ldmia	sp, {r0 - pc}		\n\t"

#endif

		:

		: "r" (kcb->jprobe_saved_regs.ARM_sp),

		  "I" (sizeof(struct pt_regs) * 2),

		  "J" (offsetof(struct pt_regs, ARM_sp)),

		  "J" (offsetof(struct pt_regs, ARM_pc)),

		  "J" (offsetof(struct pt_regs, ARM_cpsr))

		  "J" (offsetof(struct pt_regs, ARM_cpsr)),

		  "J" (offsetof(struct pt_regs, ARM_lr))

		: "memory", "cc");

}