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Commit a28e46f1 authored by Michael Ellerman's avatar Michael Ellerman
Browse files

powerpc/kernel: Check features don't change after patching 



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: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 9e8066f3

arch/powerpc/lib/feature-fixups.c

+26 −1
Original line number Diff line number Diff line
@@ -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);



	*PTRRELOC(&saved_cpu_features) = spec->cpu_features;

	*PTRRELOC(&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)	\