powerpc/64: properly initialise the stackprotector canary on SMP.

[Michael Ellerman]

On Sat, 2018-10-13 at 09:45:12 UTC, Christophe Leroy wrote:
> commit 06ec27aea9fc ("powerpc/64: add stack protector support")
> doesn't initialise the stack canary on SMP secondary CPU's paca,
> leading to the following false positive report from the
> stack protector.
> 
> smp: Bringing up secondary CPUs ...
> Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: __schedule+0x978/0xa80
> CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.19.0-rc7-next-20181010-autotest-autotest #1
> Call Trace:
> [c000001fed5b3bf0] [c000000000a0ef3c] dump_stack+0xb0/0xf4 (unreliable)
> [c000001fed5b3c30] [c0000000000f9d68] panic+0x140/0x308
> [c000001fed5b3cc0] [c0000000000f9844] __stack_chk_fail+0x24/0x30
> [c000001fed5b3d20] [c000000000a2c3a8] __schedule+0x978/0xa80
> [c000001fed5b3e00] [c000000000a2c9b4] schedule_idle+0x34/0x60
> [c000001fed5b3e30] [c00000000013d344] do_idle+0x224/0x3d0
> [c000001fed5b3ec0] [c00000000013d6e0] cpu_startup_entry+0x30/0x50
> [c000001fed5b3ef0] [c000000000047f34] start_secondary+0x4d4/0x520
> [c000001fed5b3f90] [c00000000000b370] start_secondary_prolog+0x10/0x14
> 
> This patch properly initialises the stack_canary of the secondary
> idle tasks.
> 
> Reported-by: Abdul Haleem <abdhalee at linux.vnet.ibm.com>
> Fixes: 06ec27aea9fc ("powerpc/64: add stack protector support")
> Signed-off-by: Christophe Leroy <christophe.leroy at c-s.fr>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/7241d26e8175e95290a6549a470c33

cheers