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/entry.S | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'arch/i386/kernel/entry.S') diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S index 3e4aa1fd33e2..7f92ceb428ad 100644 --- a/arch/i386/kernel/entry.S +++ b/arch/i386/kernel/entry.S @@ -132,7 +132,7 @@ VM_MASK = 0x00020000 movl $(__USER_DS), %edx; \ movl %edx, %ds; \ movl %edx, %es; \ - movl $(__KERNEL_PDA), %edx; \ + movl $(__KERNEL_PERCPU), %edx; \ movl %edx, %fs #define RESTORE_INT_REGS \ @@ -556,7 +556,6 @@ END(syscall_badsys) #define FIXUP_ESPFIX_STACK \ /* since we are on a wrong stack, we cant make it a C code :( */ \ - movl %fs:PDA_cpu, %ebx; \ PER_CPU(gdt_page, %ebx); \ GET_DESC_BASE(GDT_ENTRY_ESPFIX_SS, %ebx, %eax, %ax, %al, %ah); \ addl %esp, %eax; \ @@ -681,7 +680,7 @@ error_code: pushl %fs CFI_ADJUST_CFA_OFFSET 4 /*CFI_REL_OFFSET fs, 0*/ - movl $(__KERNEL_PDA), %ecx + movl $(__KERNEL_PERCPU), %ecx movl %ecx, %fs UNWIND_ESPFIX_STACK popl %ecx -- cgit v1.2.3-59-g8ed1b