Commit 1d0afc0d authored Mar 31, 2018 by Michael Ellerman

powerpc/64e: Fix oops due to deferral of paca allocation



On 64-bit Book3E systems, in setup_tlb_core_data() we reference other
CPUs pacas. But in commit 59f57774 ("powerpc/64: Defer paca
allocation until memory topology is discovered") the allocation of
non-boot-CPU pacas was deferred until later in boot.

This leads to an oops:

  CPU maps initialized for 1 thread per core
  Unable to handle kernel paging request for data at address 0x8888888888888918
  Faulting instruction address: 0xc000000000e2f0d0
  Oops: Kernel access of bad area, sig: 11 [#1]
  NIP .setup_tlb_core_data+0xdc/0x160
  Call Trace:
    .setup_tlb_core_data+0x5c/0x160 (unreliable)
    .setup_arch+0x80/0x348
    .start_kernel+0x7c/0x598
    start_here_common+0x1c/0x40

Luckily setup_tlb_core_data() is called immediately prior to
smp_setup_pacas(). So simply switching their order is sufficient to
fix the oops and seems unlikely to have any other unwanted side
effects.

Fixes: 59f57774 ("powerpc/64: Defer paca allocation until memory topology is discovered")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

parent ca9a16c3

arch/powerpc/kernel/setup-common.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -915,9 +915,6 @@ void __init setup_arch(char **cmdline_p)
		/* Parse memory topology */
		mem_topology_setup();

		/* On BookE, setup per-core TLB data structures. */
		setup_tlb_core_data();

		/*
		* Release secondary cpus out of their spinloops at 0x60 now that
		* we can map physical -> logical CPU ids.
		@@ -927,6 +924,10 @@ void __init setup_arch(char **cmdline_p)
		*/
		#ifdef CONFIG_SMP
		smp_setup_pacas();

		/* On BookE, setup per-core TLB data structures. */
		setup_tlb_core_data();

		smp_release_cpus();
		#endif