From 7c3576d261ce046789a7db14f43303f8120910c7 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Wed, 2 May 2007 19:27:16 +0200 Subject: [PATCH] i386: Convert PDA into the percpu section Currently x86 (similar to x84-64) has a special per-cpu structure called "i386_pda" which can be easily and efficiently referenced via the %fs register. An ELF section is more flexible than a structure, allowing any piece of code to use this area. Indeed, such a section already exists: the per-cpu area. So this patch: (1) Removes the PDA and uses per-cpu variables for each current member. (2) Replaces the __KERNEL_PDA segment with __KERNEL_PERCPU. (3) Creates a per-cpu mirror of __per_cpu_offset called this_cpu_off, which can be used to calculate addresses for this CPU's variables. (4) Simplifies startup, because %fs doesn't need to be loaded with a special segment at early boot; it can be deferred until the first percpu area is allocated (or never for UP). The result is less code and one less x86-specific concept. Signed-off-by: Rusty Russell Signed-off-by: Jeremy Fitzhardinge Signed-off-by: Andi Kleen Cc: Andi Kleen --- arch/i386/kernel/cpu/common.c | 17 +++-------------- 1 file changed, 3 insertions(+), 14 deletions(-) (limited to 'arch/i386/kernel/cpu/common.c') diff --git a/arch/i386/kernel/cpu/common.c b/arch/i386/kernel/cpu/common.c index 7a4c036d93c..27e00565f5e 100644 --- a/arch/i386/kernel/cpu/common.c +++ b/arch/i386/kernel/cpu/common.c @@ -18,7 +18,6 @@ #include #include #endif -#include #include "cpu.h" @@ -47,13 +46,10 @@ DEFINE_PER_CPU(struct gdt_page, gdt_page) = { .gdt = { [GDT_ENTRY_APMBIOS_BASE+2] = { 0x0000ffff, 0x00409200 }, /* data */ [GDT_ENTRY_ESPFIX_SS] = { 0x00000000, 0x00c09200 }, - [GDT_ENTRY_PDA] = { 0x00000000, 0x00c09200 }, /* set in setup_pda */ + [GDT_ENTRY_PERCPU] = { 0x00000000, 0x00000000 }, } }; EXPORT_PER_CPU_SYMBOL_GPL(gdt_page); -DEFINE_PER_CPU(struct i386_pda, _cpu_pda); -EXPORT_PER_CPU_SYMBOL(_cpu_pda); - static int cachesize_override __cpuinitdata = -1; static int disable_x86_fxsr __cpuinitdata; static int disable_x86_serial_nr __cpuinitdata = 1; @@ -634,21 +630,14 @@ void __init early_cpu_init(void) #endif } -/* Make sure %gs is initialized properly in idle threads */ +/* Make sure %fs is initialized properly in idle threads */ struct pt_regs * __devinit idle_regs(struct pt_regs *regs) { memset(regs, 0, sizeof(struct pt_regs)); - regs->xfs = __KERNEL_PDA; + regs->xfs = __KERNEL_PERCPU; return regs; } -/* Initial PDA used by boot CPU */ -struct i386_pda boot_pda = { - ._pda = &boot_pda, - .cpu_number = 0, - .pcurrent = &init_task, -}; - /* * cpu_init() initializes state that is per-CPU. Some data is already * initialized (naturally) in the bootstrap process, such as the GDT -- cgit v1.2.3