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Diffstat (limited to 'arch/um/include/asm/cpufeature.h')
| -rw-r--r-- | arch/um/include/asm/cpufeature.h | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/arch/um/include/asm/cpufeature.h b/arch/um/include/asm/cpufeature.h new file mode 100644 index 0000000000..4b6d1b526b --- /dev/null +++ b/arch/um/include/asm/cpufeature.h @@ -0,0 +1,142 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_UM_CPUFEATURE_H +#define _ASM_UM_CPUFEATURE_H + +#include <asm/processor.h> + +#if defined(__KERNEL__) && !defined(__ASSEMBLY__) + +#include <asm/asm.h> +#include <linux/bitops.h> + +extern const char * const x86_cap_flags[NCAPINTS*32]; +extern const char * const x86_power_flags[32]; +#define X86_CAP_FMT "%s" +#define x86_cap_flag(flag) x86_cap_flags[flag] + +/* + * In order to save room, we index into this array by doing + * X86_BUG_<name> - NCAPINTS*32. + */ +extern const char * const x86_bug_flags[NBUGINTS*32]; + +#define test_cpu_cap(c, bit) \ + test_bit(bit, (unsigned long *)((c)->x86_capability)) + +/* + * There are 32 bits/features in each mask word. The high bits + * (selected with (bit>>5) give us the word number and the low 5 + * bits give us the bit/feature number inside the word. + * (1UL<<((bit)&31) gives us a mask for the feature_bit so we can + * see if it is set in the mask word. + */ +#define CHECK_BIT_IN_MASK_WORD(maskname, word, bit) \ + (((bit)>>5)==(word) && (1UL<<((bit)&31) & maskname##word )) + +#define cpu_has(c, bit) \ + test_cpu_cap(c, bit) + +#define this_cpu_has(bit) \ + (__builtin_constant_p(bit) && REQUIRED_MASK_BIT_SET(bit) ? 1 : \ + x86_this_cpu_test_bit(bit, \ + (unsigned long __percpu *)&cpu_info.x86_capability)) + +/* + * This macro is for detection of features which need kernel + * infrastructure to be used. It may *not* directly test the CPU + * itself. Use the cpu_has() family if you want true runtime + * testing of CPU features, like in hypervisor code where you are + * supporting a possible guest feature where host support for it + * is not relevant. + */ +#define cpu_feature_enabled(bit) \ + (__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 : static_cpu_has(bit)) + +#define boot_cpu_has(bit) cpu_has(&boot_cpu_data, bit) + +#define set_cpu_cap(c, bit) set_bit(bit, (unsigned long *)((c)->x86_capability)) + +extern void setup_clear_cpu_cap(unsigned int bit); + +#define setup_force_cpu_cap(bit) do { \ + set_cpu_cap(&boot_cpu_data, bit); \ + set_bit(bit, (unsigned long *)cpu_caps_set); \ +} while (0) + +#define setup_force_cpu_bug(bit) setup_force_cpu_cap(bit) + +/* + * Static testing of CPU features. Used the same as boot_cpu_has(). It + * statically patches the target code for additional performance. Use + * static_cpu_has() only in fast paths, where every cycle counts. Which + * means that the boot_cpu_has() variant is already fast enough for the + * majority of cases and you should stick to using it as it is generally + * only two instructions: a RIP-relative MOV and a TEST. + */ +static __always_inline bool _static_cpu_has(u16 bit) +{ + asm_volatile_goto("1: jmp 6f\n" + "2:\n" + ".skip -(((5f-4f) - (2b-1b)) > 0) * " + "((5f-4f) - (2b-1b)),0x90\n" + "3:\n" + ".section .altinstructions,\"a\"\n" + " .long 1b - .\n" /* src offset */ + " .long 4f - .\n" /* repl offset */ + " .word %P[always]\n" /* always replace */ + " .byte 3b - 1b\n" /* src len */ + " .byte 5f - 4f\n" /* repl len */ + " .byte 3b - 2b\n" /* pad len */ + ".previous\n" + ".section .altinstr_replacement,\"ax\"\n" + "4: jmp %l[t_no]\n" + "5:\n" + ".previous\n" + ".section .altinstructions,\"a\"\n" + " .long 1b - .\n" /* src offset */ + " .long 0\n" /* no replacement */ + " .word %P[feature]\n" /* feature bit */ + " .byte 3b - 1b\n" /* src len */ + " .byte 0\n" /* repl len */ + " .byte 0\n" /* pad len */ + ".previous\n" + ".section .altinstr_aux,\"ax\"\n" + "6:\n" + " testb %[bitnum],%[cap_byte]\n" + " jnz %l[t_yes]\n" + " jmp %l[t_no]\n" + ".previous\n" + : : [feature] "i" (bit), + [always] "i" (X86_FEATURE_ALWAYS), + [bitnum] "i" (1 << (bit & 7)), + [cap_byte] "m" (((const char *)boot_cpu_data.x86_capability)[bit >> 3]) + : : t_yes, t_no); +t_yes: + return true; +t_no: + return false; +} + +#define static_cpu_has(bit) \ +( \ + __builtin_constant_p(boot_cpu_has(bit)) ? \ + boot_cpu_has(bit) : \ + _static_cpu_has(bit) \ +) + +#define cpu_has_bug(c, bit) cpu_has(c, (bit)) +#define set_cpu_bug(c, bit) set_cpu_cap(c, (bit)) + +#define static_cpu_has_bug(bit) static_cpu_has((bit)) +#define boot_cpu_has_bug(bit) cpu_has_bug(&boot_cpu_data, (bit)) +#define boot_cpu_set_bug(bit) set_cpu_cap(&boot_cpu_data, (bit)) + +#define MAX_CPU_FEATURES (NCAPINTS * 32) +#define cpu_have_feature boot_cpu_has + +#define CPU_FEATURE_TYPEFMT "x86,ven%04Xfam%04Xmod%04X" +#define CPU_FEATURE_TYPEVAL boot_cpu_data.x86_vendor, boot_cpu_data.x86, \ + boot_cpu_data.x86_model + +#endif /* defined(__KERNEL__) && !defined(__ASSEMBLY__) */ +#endif /* _ASM_UM_CPUFEATURE_H */ |