Michael Ellerman [off-list ref] a écrit :

Christophe Leroy [off-list ref] writes:

quoted

After reactivation of data translation by modifying MSR[DR], a isync
is required to ensure the translation is effective.

Signed-off-by: Christophe Leroy <redacted>
---
Rebased on powerpc/merge-test

@mpe: If not too late:
- change to head_32.h should be squashed into "powerpc/32: prepare  
for CONFIG_VMAP_STACK"
- change to head_32.S should be squashed into "powerpc/32s: Enable  
CONFIG_VMAP_STACK"

Signed-off-by: Christophe Leroy <redacted>
---
 arch/powerpc/kernel/head_32.S | 1 +
 arch/powerpc/kernel/head_32.h | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h
index 73a035b40dbf..a6a5fbbf8504 100644
--- a/arch/powerpc/kernel/head_32.h
+++ b/arch/powerpc/kernel/head_32.h

@@ -43,6 +43,7 @@
 	.ifeq	\for_rtas
 	li	r11, MSR_KERNEL & ~(MSR_IR | MSR_RI) /* can take DTLB miss */
 	mtmsr	r11
+	isync

Actually this one leads to:

  /home/michael/linux/arch/powerpc/kernel/head_8xx.S: Assembler messages:
  /home/michael/linux/arch/powerpc/kernel/head_8xx.S:151: Error:  
attempt to move .org backwards
  make[3]: *** [/home/michael/linux/scripts/Makefile.build:348:  
arch/powerpc/kernel/head_8xx.o] Error 1

For mpc885_ads_defconfig.

That's the alignment exception overflowing into the program check
handler:

/* Alignment exception */
	. = 0x600
Alignment:
	EXCEPTION_PROLOG handle_dar_dsisr=1
	save_dar_dsisr_on_stack r4, r5, r11
	li	r6, RPN_PATTERN
	mtspr	SPRN_DAR, r6	/* Tag DAR, to be used in DTLB Error */
	addi	r3,r1,STACK_FRAME_OVERHEAD
	EXC_XFER_STD(0x600, alignment_exception)

/* Program check exception */
	EXCEPTION(0x700, ProgramCheck, program_check_exception, EXC_XFER_STD)


Can't see an obvious/easy way to fix it.

Argh !

I think the easiest is to move the EXC_XFER_STD(0x600,  
alignment_exception) somewhere else and branch to it. There is some  
space at .0xa00

Christophe

PS: I'm afk until monday