From: Brian Gerst Date: Sun, 8 Feb 2009 14:58:39 +0000 (-0500) Subject: x86: use linker to offset symbols by __per_cpu_load X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=2add8e235cbe0dcd672c33fc322754e15500238c;p=linux-2.6-omap-h63xx.git x86: use linker to offset symbols by __per_cpu_load Impact: cleanup and bug fix Use the linker to create symbols for certain per-cpu variables that are offset by __per_cpu_load. This allows the removal of the runtime fixup of the GDT pointer, which fixes a bug with resume reported by Jiri Slaby. Reported-by: Jiri Slaby Signed-off-by: Brian Gerst Acked-by: Jiri Slaby Signed-off-by: Ingo Molnar --- diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h index 0b64af4f13a..aee103b26d0 100644 --- a/arch/x86/include/asm/percpu.h +++ b/arch/x86/include/asm/percpu.h @@ -34,6 +34,12 @@ #define PER_CPU_VAR(var) per_cpu__##var #endif /* SMP */ +#ifdef CONFIG_X86_64_SMP +#define INIT_PER_CPU_VAR(var) init_per_cpu__##var +#else +#define INIT_PER_CPU_VAR(var) per_cpu__##var +#endif + #else /* ...!ASSEMBLY */ #include @@ -45,6 +51,22 @@ #define __percpu_arg(x) "%" #x #endif +/* + * Initialized pointers to per-cpu variables needed for the boot + * processor need to use these macros to get the proper address + * offset from __per_cpu_load on SMP. + * + * There also must be an entry in vmlinux_64.lds.S + */ +#define DECLARE_INIT_PER_CPU(var) \ + extern typeof(per_cpu_var(var)) init_per_cpu_var(var) + +#ifdef CONFIG_X86_64_SMP +#define init_per_cpu_var(var) init_per_cpu__##var +#else +#define init_per_cpu_var(var) per_cpu_var(var) +#endif + /* For arch-specific code, we can use direct single-insn ops (they * don't give an lvalue though). */ extern void __bad_percpu_size(void); diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 656d02ea509..373d3f628d2 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -393,6 +393,8 @@ union irq_stack_union { }; DECLARE_PER_CPU(union irq_stack_union, irq_stack_union); +DECLARE_INIT_PER_CPU(irq_stack_union); + DECLARE_PER_CPU(char *, irq_stack_ptr); #endif diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 0f73ea42308..41b0de6df87 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -902,12 +902,8 @@ struct desc_ptr idt_descr = { 256 * 16 - 1, (unsigned long) idt_table }; DEFINE_PER_CPU_FIRST(union irq_stack_union, irq_stack_union) __aligned(PAGE_SIZE); -#ifdef CONFIG_SMP -DEFINE_PER_CPU(char *, irq_stack_ptr); /* will be set during per cpu init */ -#else DEFINE_PER_CPU(char *, irq_stack_ptr) = - per_cpu_var(irq_stack_union.irq_stack) + IRQ_STACK_SIZE - 64; -#endif + init_per_cpu_var(irq_stack_union.irq_stack) + IRQ_STACK_SIZE - 64; DEFINE_PER_CPU(unsigned long, kernel_stack) = (unsigned long)&init_thread_union - KERNEL_STACK_OFFSET + THREAD_SIZE; diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index a0a2b5ca9b7..2e648e3a5ea 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -205,19 +205,6 @@ ENTRY(secondary_startup_64) pushq $0 popfq -#ifdef CONFIG_SMP - /* - * Fix up static pointers that need __per_cpu_load added. The assembler - * is unable to do this directly. This is only needed for the boot cpu. - * These values are set up with the correct base addresses by C code for - * secondary cpus. - */ - movq initial_gs(%rip), %rax - cmpl $0, per_cpu__cpu_number(%rax) - jne 1f - addq %rax, early_gdt_descr_base(%rip) -1: -#endif /* * We must switch to a new descriptor in kernel space for the GDT * because soon the kernel won't have access anymore to the userspace @@ -275,11 +262,7 @@ ENTRY(secondary_startup_64) ENTRY(initial_code) .quad x86_64_start_kernel ENTRY(initial_gs) -#ifdef CONFIG_SMP - .quad __per_cpu_load -#else - .quad PER_CPU_VAR(irq_stack_union) -#endif + .quad INIT_PER_CPU_VAR(irq_stack_union) __FINITDATA ENTRY(stack_start) @@ -425,7 +408,7 @@ NEXT_PAGE(level2_spare_pgt) early_gdt_descr: .word GDT_ENTRIES*8-1 early_gdt_descr_base: - .quad per_cpu__gdt_page + .quad INIT_PER_CPU_VAR(gdt_page) ENTRY(phys_base) /* This must match the first entry in level2_kernel_pgt */ diff --git a/arch/x86/kernel/vmlinux_64.lds.S b/arch/x86/kernel/vmlinux_64.lds.S index 07f62d287ff..087a7f2c639 100644 --- a/arch/x86/kernel/vmlinux_64.lds.S +++ b/arch/x86/kernel/vmlinux_64.lds.S @@ -257,6 +257,14 @@ SECTIONS DWARF_DEBUG } + /* + * Per-cpu symbols which need to be offset from __per_cpu_load + * for the boot processor. + */ +#define INIT_PER_CPU(x) init_per_cpu__##x = per_cpu__##x + __per_cpu_load +INIT_PER_CPU(gdt_page); +INIT_PER_CPU(irq_stack_union); + /* * Build-time check on the image size: */