diff options
Diffstat (limited to 'src/arch/x86/include')
| -rw-r--r-- | src/arch/x86/include/arch/cpu.h | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/src/arch/x86/include/arch/cpu.h b/src/arch/x86/include/arch/cpu.h index f736a147fe..8e96fae2c2 100644 --- a/src/arch/x86/include/arch/cpu.h +++ b/src/arch/x86/include/arch/cpu.h @@ -236,11 +236,40 @@ struct cpu_info { #endif }; +/* + * This structure describes the data allocated in the %gs segment for each CPU. + * In order to read from this structure you will need to use assembly to + * reference the segment. + * + * e.g., Reading the cpu_info pointer: + * %%gs:0 + */ +struct per_cpu_segment_data { + /* + * Instead of keeping a `struct cpu_info`, we actually keep a pointer + * pointing to the cpu_info struct located in %ds. This prevents + * needing specific access functions to read the fields in the cpu_info. + */ + struct cpu_info *cpu_info; +}; + static inline struct cpu_info *cpu_info(void) { +/* We use a #if because we don't want to mess with the &s below. */ +#if CONFIG(CPU_INFO_V2) + struct cpu_info *ci = NULL; + + __asm__("mov %%gs:%c[offset], %[ci]" + : [ci] "=r" (ci) + : [offset] "i" (offsetof(struct per_cpu_segment_data, cpu_info)) + ); + + return ci; +#else char s; uintptr_t info = ALIGN_UP((uintptr_t)&s, CONFIG_STACK_SIZE) - sizeof(struct cpu_info); return (struct cpu_info *)info; +#endif /* CPU_INFO_V2 */ } struct cpuinfo_x86 { |