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lguest: prepare to make SWITCHER_ADDR a variable.

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We currently use the whole top PGD entry for the switcher, but that's
hitting the fixmap in some configurations (mainly, large NR_CPUS).
Introduce a variable, currently set to the constant.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2013-04-22 14:10:37 +09:30
parent 74ff582cd6
commit 406a590ba1
3 changed files with 14 additions and 10 deletions
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18
drivers/lguest/core.c
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@@ -20,7 +20,7 @@
#include <asm/asm-offsets.h>
#include "lg.h"
unsigned long switcher_addr;
static struct vm_struct *switcher_vma;
static struct page **switcher_page;
@@ -75,25 +75,27 @@ static __init int map_switcher(void)
}
}
switcher_addr = SWITCHER_ADDR;
/*
* First we check that the Switcher won't overlap the fixmap area at
* the top of memory. It's currently nowhere near, but it could have
* very strange effects if it ever happened.
*/
if (SWITCHER_ADDR + (TOTAL_SWITCHER_PAGES+1)*PAGE_SIZE > FIXADDR_START){
if (switcher_addr + (TOTAL_SWITCHER_PAGES+1)*PAGE_SIZE > FIXADDR_START){
err = -ENOMEM;
printk("lguest: mapping switcher would thwack fixmap\n");
goto free_pages;
}
/*
* Now we reserve the "virtual memory area" we want: 0xFFC00000
* (SWITCHER_ADDR). We might not get it in theory, but in practice
* it's worked so far. The end address needs +1 because __get_vm_area
* allocates an extra guard page, so we need space for that.
* Now we reserve the "virtual memory area" we want. We might
* not get it in theory, but in practice it's worked so far.
* The end address needs +1 because __get_vm_area allocates an
* extra guard page, so we need space for that.
*/
switcher_vma = __get_vm_area(TOTAL_SWITCHER_PAGES * PAGE_SIZE,
VM_ALLOC, SWITCHER_ADDR, SWITCHER_ADDR
VM_ALLOC, switcher_addr, switcher_addr
+ (TOTAL_SWITCHER_PAGES+1) * PAGE_SIZE);
if (!switcher_vma) {
err = -ENOMEM;
@@ -103,7 +105,7 @@ static __init int map_switcher(void)
/*
* This code actually sets up the pages we've allocated to appear at
* SWITCHER_ADDR. map_vm_area() takes the vma we allocated above, the
* switcher_addr. map_vm_area() takes the vma we allocated above, the
* kind of pages we're mapping (kernel pages), and a pointer to our
* array of struct pages. It increments that pointer, but we don't
* care.