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@xxxxxxxxxxxx>
Cc: Rabin Vincent <rabin@xxxxxx>
---
arch/arm/include/asm/fixmap.h | 2 ++
arch/arm/mm/mmu.c | 19 +++++++++++++++++++
2 files changed, 21 insertions(+)
diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
index d984ca69ce19..714606f70425 100644
--- a/arch/arm/include/asm/fixmap.h
+++ b/arch/arm/include/asm/fixmap.h
@@ -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
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 7fa0966cd15f..94eecb913f15 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -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 +393,24 @@ SET_MEMORY_FN(rw, pte_set_rw)
SET_MEMORY_FN(x, pte_set_x)
SET_MEMORY_FN(nx, pte_set_nx)
+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);
+ flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE);
+}
+
/*
* Adjust the PMD section entries according to the CPU in use.
*/
--
1.9.1
--
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