Commit 2997876c authored by Christophe Leroy's avatar Christophe Leroy Committed by Madhavan Srinivasan
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powerpc/32: Restore clearing of MSR[RI] at interrupt/syscall exit 



Commit 13799748 ("powerpc/64: use interrupt restart table to speed
up return from interrupt") removed the inconditional clearing of
MSR[RI] when returning from interrupt into kernel. But powerpc/32
doesn't implement interrupt restart table hence still need MSR[RI]
to be cleared.

It could be added back in interrupt_exit_kernel_prepare() but it is
easier and better to add it back in entry_32.S for following reasons:
- Writing to MSR must be followed by a synchronising instruction
- The smaller the non recoverable section is the better it is

So add a macro called clr_ri and use it in the three places that play
up with SRR0/SRR1. Use it just before another mtspr for synchronisation
to avoid having to add an isync.

Now that's done in entry_32.S, exit_must_hard_disable() can return
false for non book3s/64, taking into account that BOOKE doesn't have
MSR_RI.

Also add back blacklisting syscall_exit_finish for kprobe. This was
initially added by commit 7cdf4401 ("powerpc/entry32: Blacklist
syscall exit points for kprobe.") then lost with
commit 6f76a011 ("powerpc/syscall: implement system call
entry/exit logic in C for PPC32").

Fixes: 6f76a011 ("powerpc/syscall: implement system call entry/exit logic in C for PPC32")
Fixes: 13799748 ("powerpc/64: use interrupt restart table to speed up return from interrupt")
Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarMadhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/66d0ab070563ad460ed481328ab0887c27f21a2c.1757593807.git.christophe.leroy@csgroup.eu
parent 98fa2360

arch/powerpc/kernel/entry_32.S

+17 −1
Original line number Diff line number Diff line
@@ -101,6 +101,17 @@ SYM_FUNC_END(__kuep_unlock) 
.endm

#endif



.macro	clr_ri trash

#ifndef CONFIG_BOOKE

#ifdef CONFIG_PPC_8xx

	mtspr   SPRN_NRI, \trash

#else

	li	\trash, MSR_KERNEL & ~MSR_RI

	mtmsr	\trash

#endif

#endif

.endm



	.globl	transfer_to_syscall

transfer_to_syscall:

	stw	r3, ORIG_GPR3(r1)
@@ -149,6 +160,7 @@ ret_from_syscall: 
	cmpwi	r3,0

	REST_GPR(3, r1)

syscall_exit_finish:

	clr_ri	r4

	mtspr	SPRN_SRR0,r7

	mtspr	SPRN_SRR1,r8
@@ -168,6 +180,7 @@ syscall_exit_finish: 
	REST_GPR(0, r1)

	REST_GPRS(3, 12, r1)

	b	1b

_ASM_NOKPROBE_SYMBOL(syscall_exit_finish)



#ifdef CONFIG_44x

.L44x_icache_flush:
@@ -224,10 +237,11 @@ fast_exception_return: 
	/* Clear the exception marker on the stack to avoid confusing stacktrace */

	li	r10, 0

	stw	r10, 8(r11)

	REST_GPR(10, r11)

	clr_ri	r10

	mtspr	SPRN_SRR1,r9

	mtspr	SPRN_SRR0,r12

	REST_GPR(9, r11)

	REST_GPR(10, r11)

	REST_GPR(12, r11)

	REST_GPR(11, r11)

	rfi
@@ -256,6 +270,7 @@ interrupt_return: 
.Lfast_user_interrupt_return:

	lwz	r11,_NIP(r1)

	lwz	r12,_MSR(r1)

	clr_ri	r4

	mtspr	SPRN_SRR0,r11

	mtspr	SPRN_SRR1,r12
@@ -299,6 +314,7 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS) 
	cmpwi	cr1,r3,0

	lwz	r11,_NIP(r1)

	lwz	r12,_MSR(r1)

	clr_ri	r4

	mtspr	SPRN_SRR0,r11

	mtspr	SPRN_SRR1,r12

arch/powerpc/kernel/interrupt.c

+1 −1
Original line number Diff line number Diff line
@@ -38,7 +38,7 @@ static inline bool exit_must_hard_disable(void) 
#else

static inline bool exit_must_hard_disable(void)

{

	return true;

	return false;

}

#endif