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| author |   Jeremy Fitzhardinge <jeremy@goop.org> | 2007-05-02 19:27:16 +0200 |
|---|---|---|
| committer |   Andi Kleen <andi@basil.nowhere.org> | 2007-05-02 19:27:16 +0200 |
| commit | 7c3576d261ce046789a7db14f43303f8120910c7 (patch) | |
| tree | ad27a8459bbcdb183fe2411aec3b840942992ad5 /arch/i386/kernel/entry.S | |
| parent | [PATCH] i386: Page-align the GDT (diff) | |
| download | linux-dev-7c3576d261ce046789a7db14f43303f8120910c7.tar.xz linux-dev-7c3576d261ce046789a7db14f43303f8120910c7.zip | |
[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 <rusty@rustcorp.com.au>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Diffstat (limited to 'arch/i386/kernel/entry.S')
| -rw-r--r-- | arch/i386/kernel/entry.S | 5 |
1 files changed, 2 insertions, 3 deletions
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 |