Early in boot we binary patch some sections of code based on the CPU and
MMU feature bits. But it is a one-time patching, there is no facility
for repatching the code later if the set of features change.
It is a major bug if the set of features changes after we've done the
code patching - so add a check for it.
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
---
arch/powerpc/lib/feature-fixups.c | 27 ++++++++++++++++++++++++++-
1 file changed, 26 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/lib/feature-fixups.c
b/arch/powerpc/lib/feature-fixups.c
index defb2998b818..854b8ba40f8e 100644
--- a/arch/powerpc/lib/feature-fixups.c
+++ b/arch/powerpc/lib/feature-fixups.c
@@ -152,10 +152,19 @@ static void do_final_fixups(void)
#endif
}
-void apply_feature_fixups(void)
+static unsigned long __initdata saved_cpu_features;
+static unsigned int __initdata saved_mmu_features;
+#ifdef CONFIG_PPC64
+static unsigned long __initdata saved_firmware_features;
+#endif
+
+void __init apply_feature_fixups(void)
{
struct cpu_spec *spec = *PTRRELOC(&cur_cpu_spec);
+ saved_cpu_features = spec->cpu_features;
+ saved_mmu_features = spec->mmu_features;
+
/*
* Apply the CPU-specific and firmware specific fixups to kernel text
* (nop out sections not relevant to this CPU or this firmware).
@@ -173,12 +182,28 @@ void apply_feature_fixups(void)
PTRRELOC(&__stop___lwsync_fixup));
#ifdef CONFIG_PPC64
+ saved_firmware_features = powerpc_firmware_features;
do_feature_fixups(powerpc_firmware_features,
&__start___fw_ftr_fixup, &__stop___fw_ftr_fixup);
#endif
do_final_fixups();
}
+static int __init check_features(void)
+{
+ WARN(saved_cpu_features != cur_cpu_spec->cpu_features,
+ "CPU features changed after feature patching!\n");
+ WARN(saved_mmu_features != cur_cpu_spec->mmu_features,
+ "MMU features changed after feature patching!\n");
+#ifdef CONFIG_PPC64
+ WARN(saved_firmware_features != powerpc_firmware_features,
+ "Firmware features changed after feature patching!\n");
+#endif
+
+ return 0;
+}
+late_initcall(check_features);
+
#ifdef CONFIG_FTR_FIXUP_SELFTEST
#define check(x) \
--
2.7.4
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