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Message-ID: <lsq.1368193181.523881156@decadent.org.uk> Date: Fri, 10 May 2013 14:39:41 +0100 From: Ben Hutchings <ben@...adent.org.uk> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org CC: akpm@...ux-foundation.org, "Benjamin Herrenschmidt" <benh@...nel.crashing.org>, "Michael Neuling" <michael.neuling@....ibm.com>, "Michael Neuling" <mikey@...ling.org> Subject: [060/118] powerpc: Add isync to copy_and_flush 3.2.45-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Michael Neuling <michael.neuling@....ibm.com> 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 <mikey@...ling.org> Signed-off-by: Benjamin Herrenschmidt <benh@...nel.crashing.org> Signed-off-by: Ben Hutchings <ben@...adent.org.uk> --- arch/powerpc/kernel/head_64.S | 1 + 1 file changed, 1 insertion(+) --- a/arch/powerpc/kernel/head_64.S +++ b/arch/powerpc/kernel/head_64.S @@ -502,6 +502,7 @@ _GLOBAL(copy_and_flush) sync addi r5,r5,8 addi r6,r6,8 + isync blr .align 8 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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