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arm: fixmap: implement __set_fixmap() 

This is used from set_fixmap() and clear_fixmap() via asm-generic/fixmap.h.
Also makes sure that the fixmap allocation fits into the expected range.

Based on patch by Rabin Vincent.

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Rabin Vincent <rabin@rab.in>
Acked-by: Nicolas Pitre <nico@linaro.org>
This commit is contained in:
Kees Cook 2014-04-04 23:27:49 +02:00
parent 836a241832
commit 99b4ac9afc
2 changed files with 26 additions and 0 deletions
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2
arch/arm/include/asm/fixmap.h
View File

@ -14,6 +14,8 @@ enum fixed_addresses {
__end_of_fixed_addresses
};
void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot);
#include <asm-generic/fixmap.h>
#endif

24
arch/arm/mm/mmu.c
View File

@ -22,6 +22,7 @@
#include <asm/cputype.h>
#include <asm/sections.h>
#include <asm/cachetype.h>
#include <asm/fixmap.h>
#include <asm/sections.h>
#include <asm/setup.h>
#include <asm/smp_plat.h>
@ -392,6 +393,29 @@ SET_MEMORY_FN(rw, pte_set_rw)
SET_MEMORY_FN(x, pte_set_x)
SET_MEMORY_FN(nx, pte_set_nx)
/*
* To avoid TLB flush broadcasts, this uses local_flush_tlb_kernel_range().
* As a result, this can only be called with preemption disabled, as under
* stop_machine().
*/
void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot)
{
unsigned long vaddr = __fix_to_virt(idx);
pte_t *pte = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
/* Make sure fixmap region does not exceed available allocation. */
BUILD_BUG_ON(FIXADDR_START + (__end_of_fixed_addresses * PAGE_SIZE) >
FIXADDR_END);
BUG_ON(idx >= __end_of_fixed_addresses);
if (pgprot_val(prot))
set_pte_at(NULL, vaddr, pte,
pfn_pte(phys >> PAGE_SHIFT, prot));
else
pte_clear(NULL, vaddr, pte);
local_flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE);
}
/*
* Adjust the PMD section entries according to the CPU in use.
*/