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| author | Nicholas Miehlbradt <nicholas@linux.ibm.com> | 2024-04-08 05:23:58 +0000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2024-04-15 12:53:39 +1000 |
| commit | 676b2f99b0f6cd11193eeae13c976565c3fc7545 (patch) | |
| tree | fd5692814cfee5729a7b9e6c13543aeee269643d | |
| parent | 676abf7c39267080ab81597c6d4f372a10c0fc21 (diff) | |
| download | lwn-676b2f99b0f6cd11193eeae13c976565c3fc7545.tar.gz lwn-676b2f99b0f6cd11193eeae13c976565c3fc7545.zip | |
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: Nicholas Miehlbradt <nicholas@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240408052358.5030-1-nicholas@linux.ibm.com
| -rw-r--r-- | arch/powerpc/include/asm/cpu_has_feature.h | 2 | ||||
| -rw-r--r-- | arch/powerpc/include/asm/feature-fixups.h | 2 | ||||
| -rw-r--r-- | arch/powerpc/include/asm/mmu.h | 2 | ||||
| -rw-r--r-- | arch/powerpc/lib/feature-fixups.c | 8 |
4 files changed, 12 insertions, 2 deletions
diff --git a/arch/powerpc/include/asm/cpu_has_feature.h b/arch/powerpc/include/asm/cpu_has_feature.h index 727d4b321937..0efabccd820c 100644 --- a/arch/powerpc/include/asm/cpu_has_feature.h +++ b/arch/powerpc/include/asm/cpu_has_feature.h @@ -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); diff --git a/arch/powerpc/include/asm/feature-fixups.h b/arch/powerpc/include/asm/feature-fixups.h index 77824bd289a3..17d168dd8b49 100644 --- a/arch/powerpc/include/asm/feature-fixups.h +++ b/arch/powerpc/include/asm/feature-fixups.h @@ -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); diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h index 3b72c7ed24cf..24f830cf9bb4 100644 --- a/arch/powerpc/include/asm/mmu.h +++ b/arch/powerpc/include/asm/mmu.h @@ -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); diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c index 4f82581ca203..b7201ba50b2e 100644 --- a/arch/powerpc/lib/feature-fixups.c +++ b/arch/powerpc/lib/feature-fixups.c @@ -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) |