| Message ID | 29244.1366799409@ale.ozlabs.ibm.com (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Commit | 29ce3c5073057991217916abc25628e906911757 |
| Delegated to: | Benjamin Herrenschmidt |
| Headers | show |
On Wed, 2013-04-24 at 20:30 +1000, Michael Neuling wrote:
> benh: we should get this in 3.9 ASAP.
Considering that the bug has been there *forever* I don't think I have a
real standing to try to shove it down Linus throat as a "regression
fix" :-)
I'll put the fix in 3.10 and let it trickle down to stable.
Cheers,
Ben.
> Considering that the bug has been there *forever* I don't think I have a > real standing to try to shove it down Linus throat as a "regression > fix" :-) True, sorry. > I'll put the fix in 3.10 and let it trickle down to stable. Thanks Mikey
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S index 0886ae6..b61363d 100644 --- a/arch/powerpc/kernel/head_64.S +++ b/arch/powerpc/kernel/head_64.S @@ -509,6 +509,7 @@ _GLOBAL(copy_and_flush) sync addi r5,r5,8 addi r6,r6,8 + isync blr .align 8
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 <mikey@neuling.org> cc: stable@kernel.org --- benh: we should get this in 3.9 ASAP.