i386: Implement smp_processor_id() with the PDA From: Jeremy Fitzhardinge Use the cpu_number in the PDA to implement raw_smp_processor_id. This is a little simpler than using thread_info, though the cpu field in thread_info cannot be removed since it is used for things other than getting the current CPU in common code. Signed-off-by: Jeremy Fitzhardinge Signed-off-by: Andi Kleen Cc: Chuck Ebbert <76306.1226@compuserve.com> Cc: Zachary Amsden Cc: Jan Beulich Cc: Andi Kleen Signed-off-by: Andrew Morton --- arch/i386/kernel/asm-offsets.c | 4 +++- arch/i386/kernel/cpu/common.c | 2 ++ arch/i386/kernel/entry.S | 3 +-- include/asm-i386/pda.h | 2 ++ include/asm-i386/smp.h | 3 ++- 5 files changed, 10 insertions(+), 4 deletions(-) Index: linux/arch/i386/kernel/asm-offsets.c =================================================================== --- linux.orig/arch/i386/kernel/asm-offsets.c +++ linux/arch/i386/kernel/asm-offsets.c @@ -51,7 +51,6 @@ void foo(void) OFFSET(TI_exec_domain, thread_info, exec_domain); OFFSET(TI_flags, thread_info, flags); OFFSET(TI_status, thread_info, status); - OFFSET(TI_cpu, thread_info, cpu); OFFSET(TI_preempt_count, thread_info, preempt_count); OFFSET(TI_addr_limit, thread_info, addr_limit); OFFSET(TI_restart_block, thread_info, restart_block); @@ -97,4 +96,7 @@ void foo(void) DEFINE(VDSO_PRELINK, VDSO_PRELINK); OFFSET(crypto_tfm_ctx_offset, crypto_tfm, __crt_ctx); + + BLANK(); + OFFSET(PDA_cpu, i386_pda, cpu_number); } Index: linux/arch/i386/kernel/cpu/common.c =================================================================== --- linux.orig/arch/i386/kernel/cpu/common.c +++ linux/arch/i386/kernel/cpu/common.c @@ -650,6 +650,7 @@ __cpuinit int alloc_gdt(int cpu) /* Initial PDA used by boot CPU */ struct i386_pda boot_pda = { ._pda = &boot_pda, + .cpu_number = 0, }; static inline void set_kernel_gs(void) @@ -694,6 +695,7 @@ __cpuinit int init_gdt(int cpu, struct t memset(pda, 0, sizeof(*pda)); pda->_pda = pda; + pda->cpu_number = cpu; return 1; } Index: linux/arch/i386/kernel/entry.S =================================================================== --- linux.orig/arch/i386/kernel/entry.S +++ linux/arch/i386/kernel/entry.S @@ -524,8 +524,7 @@ syscall_badsys: #define FIXUP_ESPFIX_STACK \ /* since we are on a wrong stack, we cant make it a C code :( */ \ - GET_THREAD_INFO(%ebp); \ - movl TI_cpu(%ebp), %ebx; \ + movl %gs:PDA_cpu, %ebx; \ PER_CPU(cpu_gdt_descr, %ebx); \ movl GDS_address(%ebx), %ebx; \ GET_DESC_BASE(GDT_ENTRY_ESPFIX_SS, %ebx, %eax, %ax, %al, %ah); \ Index: linux/include/asm-i386/pda.h =================================================================== --- linux.orig/include/asm-i386/pda.h +++ linux/include/asm-i386/pda.h @@ -11,6 +11,8 @@ struct i386_pda { struct i386_pda *_pda; /* pointer to self */ + + int cpu_number; }; extern struct i386_pda *_cpu_pda[]; Index: linux/include/asm-i386/smp.h =================================================================== --- linux.orig/include/asm-i386/smp.h +++ linux/include/asm-i386/smp.h @@ -8,6 +8,7 @@ #include #include #include +#include #endif #ifdef CONFIG_X86_LOCAL_APIC @@ -56,7 +57,7 @@ extern void cpu_uninit(void); * from the initial startup. We map APIC_BASE very early in page_setup(), * so this is correct in the x86 case. */ -#define raw_smp_processor_id() (current_thread_info()->cpu) +#define raw_smp_processor_id() (read_pda(cpu_number)) extern cpumask_t cpu_callout_map; extern cpumask_t cpu_callin_map;