4.9-stable review patch. If anyone has any objections, please let me know.
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From: Michael Ellerman mpe@ellerman.id.au
[ Upstream commit 0834d627fbea00c1444075eb3e448e1974da452d ]
In mpic_physmask() we loop over all CPUs up to 32, then get the hard SMP processor id of that CPU.
Currently that's possibly walking off the end of the paca array, but in a future patch we will change the paca array to be an array of pointers, and in that case we will get a NULL for missing CPUs and oops. eg:
Unable to handle kernel paging request for data at address 0x88888888888888b8 Faulting instruction address: 0xc00000000004e380 Oops: Kernel access of bad area, sig: 11 [#1] ... NIP .mpic_set_affinity+0x60/0x1a0 LR .irq_do_set_affinity+0x48/0x100
Fix it by checking the CPU is possible, this also fixes the code if there are gaps in the CPU numbering which probably never happens on mpic systems but who knows.
Debugged-by: Nicholas Piggin npiggin@gmail.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/powerpc/sysdev/mpic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/powerpc/sysdev/mpic.c +++ b/arch/powerpc/sysdev/mpic.c @@ -626,7 +626,7 @@ static inline u32 mpic_physmask(u32 cpum int i; u32 mask = 0;
- for (i = 0; i < min(32, NR_CPUS); ++i, cpumask >>= 1) + for (i = 0; i < min(32, NR_CPUS) && cpu_possible(i); ++i, cpumask >>= 1) mask |= (cpumask & 1) << get_hard_smp_processor_id(i); return mask; }