Revert "x86/mm: Limit mmap() of /dev/mem to valid physical addresses"

This reverts commit ce56a86e2ade45d052b3228cdfebe913a1ae7381.

There's unanticipated interaction with some boot parameters like 'mem=',
which now cause the new checks via valid_mmap_phys_addr_range() to be too
restrictive, crashing a Qemu bootup in fact, as reported by Fengguang Wu.

So while the motivation of the change is still entirely valid, we
need a few more rounds of testing to get it right - it's way too late
after -rc6, so revert it for now.

Reported-by: Fengguang Wu <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Acked-by: Craig Bergstrom <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Luis R. Rodriguez <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Toshi Kani <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>

2 files changed, 0 insertions, 16 deletions

diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index 322d25ae23ab..c40a95c33bb8 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -110,10 +110,6 @@ build_mmio_write(__writeq, "q", unsigned long, "r", )
 
 #endif
 
-#define ARCH_HAS_VALID_PHYS_ADDR_RANGE
-extern int valid_phys_addr_range(phys_addr_t addr, size_t size);
-extern int valid_mmap_phys_addr_range(unsigned long pfn, size_t size);
-
 /**
  *	virt_to_phys	-	map virtual addresses to physical
  *	@address: address to remap
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 320c6237e1d1..a99679826846 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -174,15 +174,3 @@ const char *arch_vma_name(struct vm_area_struct *vma)
 		return "[mpx]";
 	return NULL;
 }
-
-int valid_phys_addr_range(phys_addr_t addr, size_t count)
-{
-	return addr + count <= __pa(high_memory);
-}
-
-int valid_mmap_phys_addr_range(unsigned long pfn, size_t count)
-{
-	phys_addr_t addr = (phys_addr_t)pfn << PAGE_SHIFT;
-
-	return valid_phys_addr_range(addr, count);
-}