[PATCH 2/8] arm: fixmap: implement __set_fixmap()

[Kees Cook <keescook@chromium.org>]

This is used from set_fixmap() and clear_fixmap() via
asm-generic/fixmap.h.

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Rabin Vincent <rabin@rab.in>
---
 arch/arm/include/asm/fixmap.h |  2 ++
 arch/arm/mm/mmu.c             | 16 ++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
index 190142d174ee..8ee7cb4f62ca 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 8348ed6b2efe..e881ed817a8b 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 +393,21 @@ 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(FIXADDR_START), vaddr);
+
+	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