676b2f99b0
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
56 lines
1.3 KiB
C
56 lines
1.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __ASM_POWERPC_CPU_HAS_FEATURE_H
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#define __ASM_POWERPC_CPU_HAS_FEATURE_H
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#ifndef __ASSEMBLY__
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#include <linux/bug.h>
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#include <asm/cputable.h>
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static __always_inline bool early_cpu_has_feature(unsigned long feature)
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{
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return !!((CPU_FTRS_ALWAYS & feature) ||
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(CPU_FTRS_POSSIBLE & cur_cpu_spec->cpu_features & feature));
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}
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#ifdef CONFIG_JUMP_LABEL_FEATURE_CHECKS
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#include <linux/jump_label.h>
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#define NUM_CPU_FTR_KEYS BITS_PER_LONG
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extern struct static_key_true cpu_feature_keys[NUM_CPU_FTR_KEYS];
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static __always_inline bool cpu_has_feature(unsigned long feature)
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{
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int i;
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#ifndef __clang__ /* clang can't cope with this */
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BUILD_BUG_ON(!__builtin_constant_p(feature));
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#endif
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#ifdef CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG
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if (!static_key_feature_checks_initialized) {
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printk("Warning! cpu_has_feature() used prior to jump label init!\n");
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dump_stack();
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return early_cpu_has_feature(feature);
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}
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#endif
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if (CPU_FTRS_ALWAYS & feature)
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return true;
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if (!(CPU_FTRS_POSSIBLE & feature))
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return false;
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i = __builtin_ctzl(feature);
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return static_branch_likely(&cpu_feature_keys[i]);
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}
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#else
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static __always_inline bool cpu_has_feature(unsigned long feature)
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{
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return early_cpu_has_feature(feature);
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}
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#endif
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#endif /* __ASSEMBLY__ */
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#endif /* __ASM_POWERPC_CPU_HAS_FEATURE_H */
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