Commit 676b2f99 authored by Nicholas Miehlbradt's avatar Nicholas Miehlbradt Committed by Michael Ellerman
Browse files

powerpc: Add static_key_feature_checks_initialized flag 



JUMP_LABEL_FEATURE_CHECK_DEBUG used static_key_intialized to determine
whether {cpu,mmu}_has_feature() is used before static keys were
initialized. However, {cpu,mmu}_has_feature() should not be used before
setup_feature_keys() is called but static_key_initialized is set well
before this by the call to jump_label_init() in early_init_devtree().
This creates a window in which JUMP_LABEL_FEATURE_CHECK_DEBUG will not
detect misuse and report errors. Add a flag specifically to indicate
when {cpu,mmu}_has_feature() is safe to use.

Signed-off-by: default avatarNicholas Miehlbradt <nicholas@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240408052358.5030-1-nicholas@linux.ibm.com
parent 676abf7c

arch/powerpc/include/asm/cpu_has_feature.h

+1 −1
Original line number Diff line number Diff line
@@ -29,7 +29,7 @@ static __always_inline bool cpu_has_feature(unsigned long feature) 
#endif



#ifdef CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG

	if (!static_key_initialized) {

	if (!static_key_feature_checks_initialized) {

		printk("Warning! cpu_has_feature() used prior to jump label init!\n");

		dump_stack();

		return early_cpu_has_feature(feature);

arch/powerpc/include/asm/feature-fixups.h

+2 −0
Original line number Diff line number Diff line
@@ -291,6 +291,8 @@ extern long __start___rfi_flush_fixup, __stop___rfi_flush_fixup; 
extern long __start___barrier_nospec_fixup, __stop___barrier_nospec_fixup;

extern long __start__btb_flush_fixup, __stop__btb_flush_fixup;



extern bool static_key_feature_checks_initialized;



void apply_feature_fixups(void);

void update_mmu_feature_fixups(unsigned long mask);

void setup_feature_keys(void);

arch/powerpc/include/asm/mmu.h

+1 −1
Original line number Diff line number Diff line
@@ -251,7 +251,7 @@ static __always_inline bool mmu_has_feature(unsigned long feature) 
#endif



#ifdef CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG

	if (!static_key_initialized) {

	if (!static_key_feature_checks_initialized) {

		printk("Warning! mmu_has_feature() used prior to jump label init!\n");

		dump_stack();

		return early_mmu_has_feature(feature);

arch/powerpc/lib/feature-fixups.c

+8 −0
Original line number Diff line number Diff line
@@ -25,6 +25,13 @@ 
#include <asm/firmware.h>

#include <asm/inst.h>



/*

 * Used to generate warnings if mmu or cpu feature check functions that

 * use static keys before they are initialized.

 */

bool static_key_feature_checks_initialized __read_mostly;

EXPORT_SYMBOL_GPL(static_key_feature_checks_initialized);



struct fixup_entry {

	unsigned long	mask;

	unsigned long	value;
@@ -679,6 +686,7 @@ void __init setup_feature_keys(void) 
	jump_label_init();

	cpu_feature_keys_init();

	mmu_feature_keys_init();

	static_key_feature_checks_initialized = true;

}



static int __init check_features(void)