I hit an oops at boot on the first instruction of timer_cpu_notify:
NIP [c000000000722f88] .timer_cpu_notify+0x0/0x388
The code should look like:
c000000000722f78: eb e9 00 30 ld r31,48(r9)
c000000000722f7c: 2f bf 00 00 cmpdi cr7,r31,0
c000000000722f80: 40 9e ff 44 bne+ cr7,c000000000722ec4
c000000000722f84: 4b ff ff 74 b c000000000722ef8
c000000000722f88 <.timer_cpu_notify>:
c000000000722f88: 7c 08 02 a6 mflr r0
c000000000722f8c: 2f a4 00 07 cmpdi cr7,r4,7
c000000000722f90: fb c1 ff f0 std r30,-16(r1)
c000000000722f94: fb 61 ff d8 std r27,-40(r1)
But the oops output shows:
eb61ffd8 eb81ffe0 eba1ffe8 ebc1fff0 7c0803a6 ebe1fff8 4e800020
00000000 ebe90030 c0000000 00ad0a28 00000000 2fa40007 fbc1fff0 fb61ffd8
So we scribbled over our instructions with c000000000ad0a28, which
is an address inside the jump_table ELF section.
It turns out the jump_table section is only aligned to 8 bytes but
we are aligning our entries within the section to 16 bytes. This
means our entries are offset from the table:
c000000000acd4a8 <__start___jump_table>:
...
c000000000ad0a10: c0 00 00 00 lfs f0,0(0)
c000000000ad0a14: 00 70 cd 5c .long 0x70cd5c
c000000000ad0a18: c0 00 00 00 lfs f0,0(0)
c000000000ad0a1c: 00 70 cd 90 .long 0x70cd90
c000000000ad0a20: c0 00 00 00 lfs f0,0(0)
c000000000ad0a24: 00 ac a4 20 .long 0xaca420
And the jump table sort code gets very confused and writes into the
wrong spot. Remove the alignment, and also remove the padding since
we it saves some space and we shouldn't need it.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This patch adds support for the new "jump label" feature.
Unlike x86 and sparc we just merrily patch the code with no locks etc,
as far as I know this is safe, but I'm not really sure what the x86/sparc
code is protecting against so maybe it's not.
I also don't see any reason for us to implement the poke_early() routine,
even though sparc does.
[BenH: Updated the patch to upstream generic changes]
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Anton Blanchard