Commit a616c442 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/entry32: Blacklist exception entry points for kprobe. 



kprobe does not handle events happening in real mode.

As exception entry points are running with MMU disabled,
blacklist them.

The handling of TLF_NAPPING and TLF_SLEEPING is moved before the
CONFIG_TRACE_IRQFLAGS which contains 'reenable_mmu' because from there
kprobe will be possible as the kernel will run with MMU enabled.

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@c-s.fr>
Acked-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/f61ac599855e674ebb592464d0ea32a3ba9c6644.1585670437.git.christophe.leroy@c-s.fr
parent 5f32e836

arch/powerpc/kernel/entry_32.S

+22 −15
Original line number Diff line number Diff line
@@ -50,6 +50,7 @@ mcheck_transfer_to_handler: 
	mfspr	r0,SPRN_DSRR1

	stw	r0,_DSRR1(r11)

	/* fall through */

_ASM_NOKPROBE_SYMBOL(mcheck_transfer_to_handler)



	.globl	debug_transfer_to_handler

debug_transfer_to_handler:
@@ -58,6 +59,7 @@ debug_transfer_to_handler: 
	mfspr	r0,SPRN_CSRR1

	stw	r0,_CSRR1(r11)

	/* fall through */

_ASM_NOKPROBE_SYMBOL(debug_transfer_to_handler)



	.globl	crit_transfer_to_handler

crit_transfer_to_handler:
@@ -93,6 +95,7 @@ crit_transfer_to_handler: 
	rlwinm	r0,r1,0,0,(31 - THREAD_SHIFT)

	stw	r0,KSP_LIMIT(r8)

	/* fall through */

_ASM_NOKPROBE_SYMBOL(crit_transfer_to_handler)

#endif



#ifdef CONFIG_40x
@@ -114,6 +117,7 @@ crit_transfer_to_handler: 
	rlwinm	r0,r1,0,0,(31 - THREAD_SHIFT)

	stw	r0,KSP_LIMIT(r8)

	/* fall through */

_ASM_NOKPROBE_SYMBOL(crit_transfer_to_handler)

#endif



/*
@@ -126,6 +130,7 @@ crit_transfer_to_handler: 
	.globl	transfer_to_handler_full

transfer_to_handler_full:

	SAVE_NVGPRS(r11)

_ASM_NOKPROBE_SYMBOL(transfer_to_handler_full)

	/* fall through */



	.globl	transfer_to_handler
@@ -226,6 +231,23 @@ transfer_to_handler_cont: 
	SYNC

	RFI				/* jump to handler, enable MMU */



#if defined (CONFIG_PPC_BOOK3S_32) || defined(CONFIG_E500)

4:	rlwinm	r12,r12,0,~_TLF_NAPPING

	stw	r12,TI_LOCAL_FLAGS(r2)

	b	power_save_ppc32_restore



7:	rlwinm	r12,r12,0,~_TLF_SLEEPING

	stw	r12,TI_LOCAL_FLAGS(r2)

	lwz	r9,_MSR(r11)		/* if sleeping, clear MSR.EE */

	rlwinm	r9,r9,0,~MSR_EE

	lwz	r12,_LINK(r11)		/* and return to address in LR */

	kuap_restore r11, r2, r3, r4, r5

	lwz	r2, GPR2(r11)

	b	fast_exception_return

#endif

_ASM_NOKPROBE_SYMBOL(transfer_to_handler)

_ASM_NOKPROBE_SYMBOL(transfer_to_handler_cont)



#ifdef CONFIG_TRACE_IRQFLAGS

1:	/* MSR is changing, re-enable MMU so we can notify lockdep. We need to

	 * keep interrupts disabled at this point otherwise we might risk
@@ -271,21 +293,6 @@ reenable_mmu: 
	bctr				/* jump to handler */

#endif /* CONFIG_TRACE_IRQFLAGS */



#if defined (CONFIG_PPC_BOOK3S_32) || defined(CONFIG_E500)

4:	rlwinm	r12,r12,0,~_TLF_NAPPING

	stw	r12,TI_LOCAL_FLAGS(r2)

	b	power_save_ppc32_restore



7:	rlwinm	r12,r12,0,~_TLF_SLEEPING

	stw	r12,TI_LOCAL_FLAGS(r2)

	lwz	r9,_MSR(r11)		/* if sleeping, clear MSR.EE */

	rlwinm	r9,r9,0,~MSR_EE

	lwz	r12,_LINK(r11)		/* and return to address in LR */

	kuap_restore r11, r2, r3, r4, r5

	lwz	r2, GPR2(r11)

	b	fast_exception_return

#endif



#ifndef CONFIG_VMAP_STACK

/*

 * On kernel stack overflow, load up an initial stack pointer

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