From 59973aa09eaac7eb849badd597453ec0b4230ebf Mon Sep 17 00:00:00 2001 From: Michael Neuling Date: Wed, 24 Apr 2013 00:30:09 +0000 Subject: [PATCH] powerpc: Add isync to copy_and_flush commit 29ce3c5073057991217916abc25628e906911757 upstream. In __after_prom_start we copy the kernel down to zero in two calls to copy_and_flush. After the first call (copy from 0 to copy_to_here:) we jump to the newly copied code soon after. Unfortunately there's no isync between the copy of this code and the jump to it. Hence it's possible that stale instructions could still be in the icache or pipeline before we branch to it. We've seen this on real machines and it's results in no console output after: calling quiesce... returning from prom_init The below adds an isync to ensure that the copy and flushing has completed before any branching to the new instructions occurs. Signed-off-by: Michael Neuling Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/kernel/head_64.S | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S index 9e07bd038dda..1a3607b96635 100644 --- a/arch/powerpc/kernel/head_64.S +++ b/arch/powerpc/kernel/head_64.S @@ -489,6 +489,7 @@ _GLOBAL(copy_and_flush) sync addi r5,r5,8 addi r6,r6,8 + isync blr .align 8 -- 2.39.5