3.8-stable review patch. If anyone has any objections, please let me know.
------------------
From: Michael Ellerman <michael@xxxxxxxxxxxxxx>
commit 25e138149c19fa0680147b825be475f5fd57f155 upstream.
In commit 466921c we added a hack to set the paca data_offset to zero so
that per-cpu accesses would work on the boot cpu prior to per-cpu areas
being setup. This fixed a problem with lockdep touching per-cpu areas
very early in boot.
However if we combine CONFIG_LOCK_STAT=y with any of the PPC_EARLY_DEBUG
options, we can hit the same problem in udbg_early_init(). To avoid that
we need to set the data_offset of the boot_paca also. So factor out the
fixup logic and call it for both the boot_paca, and "the paca of the
boot cpu".
Signed-off-by: Michael Ellerman <michael@xxxxxxxxxxxxxx>
Tested-by: Geoff Levand <geoff@xxxxxxxxxxxxx>
Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/kernel/setup_64.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -156,6 +156,15 @@ early_param("smt-enabled", early_smt_ena
#define check_smt_enabled()
#endif /* CONFIG_SMP */
+/** Fix up paca fields required for the boot cpu */
+static void fixup_boot_paca(void)
+{
+ /* The boot cpu is started */
+ get_paca()->cpu_start = 1;
+ /* Allow percpu accesses to work until we setup percpu data */
+ get_paca()->data_offset = 0;
+}
+
/*
* Early initialization entry point. This is called by head.S
* with MMU translation disabled. We rely on the "feature" of
@@ -185,6 +194,7 @@ void __init early_setup(unsigned long dt
/* Assume we're on cpu 0 for now. Don't write to the paca yet! */
initialise_paca(&boot_paca, 0);
setup_paca(&boot_paca);
+ fixup_boot_paca();
/* Initialize lockdep early or else spinlocks will blow */
lockdep_init();
@@ -205,11 +215,7 @@ void __init early_setup(unsigned long dt
/* Now we know the logical id of our boot cpu, setup the paca. */
setup_paca(&paca[boot_cpuid]);
-
- /* Fix up paca fields required for the boot cpu */
- get_paca()->cpu_start = 1;
- /* Allow percpu accesses to "work" until we setup percpu data */
- get_paca()->data_offset = 0;
+ fixup_boot_paca();
/* Probe the machine type */
probe_machine();
--
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