arm64: Fix overlapping VA allocations

PCI IO space was intended to be 16MiB, at 32MiB below MODULES_VADDR, but
commit d1e6dc91b5 ("arm64: Add architectural support for PCI")
extended this to cover the full 32MiB. The final 8KiB of this 32MiB is
also allocated for the fixmap, allowing for potential clashes between
the two.

This change was masked by assumptions in mem_init and the page table
dumping code, which assumed the I/O space to be 16MiB long through
seaparte hard-coded definitions.

This patch changes the definition of the PCI I/O space allocation to
live in asm/memory.h, along with the other VA space allocations. As the
fixmap allocation depends on the number of fixmap entries, this is moved
below the PCI I/O space allocation. Both the fixmap and PCI I/O space
are guarded with 2MB of padding. Sites assuming the I/O space was 16MiB
are moved over use new PCI_IO_{START,END} definitions, which will keep
in sync with the size of the IO space (now restored to 16MiB).

As a useful side effect, the use of the new PCI_IO_{START,END}
definitions prevents a build issue in the dumping code due to a (now
redundant) missing include of io.h for PCI_IOBASE.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Will Deacon <will.deacon@arm.com>
[catalin.marinas@arm.com: reorder FIXADDR and PCI_IO address_markers_idx enum]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/include/asm/io.h

@@ -26,6 +26,7 @@
 
 #include <asm/byteorder.h>
 #include <asm/barrier.h>
+#include <asm/memory.h>
 #include <asm/pgtable.h>
 #include <asm/early_ioremap.h>
 #include <asm/alternative.h>
@@ -145,8 +146,8 @@ static inline u64 __raw_readq(const volatile void __iomem *addr)
  *  I/O port access primitives.
  */
 #define arch_has_dev_port()	(1)
-#define IO_SPACE_LIMIT		(SZ_32M - 1)
-#define PCI_IOBASE		((void __iomem *)(MODULES_VADDR - SZ_32M))
+#define IO_SPACE_LIMIT		(PCI_IO_SIZE - 1)
+#define PCI_IOBASE		((void __iomem *)PCI_IO_START)
 
 /*
  * String version of I/O memory access operations.

arch/arm64/include/asm/memory.h

@@ -32,6 +32,12 @@
  */
 #define UL(x) _AC(x, UL)
 
+/*
+ * Size of the PCI I/O space. This must remain a power of two so that
+ * IO_SPACE_LIMIT acts as a mask for the low bits of I/O addresses.
+ */
+#define PCI_IO_SIZE		SZ_16M
+
 /*
  * PAGE_OFFSET - the virtual address of the start of the kernel image (top
  *		 (VA_BITS - 1))
@@ -45,7 +51,9 @@
 #define PAGE_OFFSET		(UL(0xffffffffffffffff) << (VA_BITS - 1))
 #define MODULES_END		(PAGE_OFFSET)
 #define MODULES_VADDR		(MODULES_END - SZ_64M)
-#define FIXADDR_TOP		(MODULES_VADDR - SZ_2M - PAGE_SIZE)
+#define PCI_IO_END		(MODULES_VADDR - SZ_2M)
+#define PCI_IO_START		(PCI_IO_END - PCI_IO_SIZE)
+#define FIXADDR_TOP		(PCI_IO_START - SZ_2M)
 #define TASK_SIZE_64		(UL(1) << VA_BITS)
 
 #ifdef CONFIG_COMPAT

arch/arm64/mm/dump.c

@@ -36,10 +36,10 @@ enum address_markers_idx {
 	VMEMMAP_START_NR,
 	VMEMMAP_END_NR,
 #endif
-	PCI_START_NR,
-	PCI_END_NR,
 	FIXADDR_START_NR,
 	FIXADDR_END_NR,
+	PCI_START_NR,
+	PCI_END_NR,
 	MODULES_START_NR,
 	MODUELS_END_NR,
 	KERNEL_SPACE_NR,
@@ -52,10 +52,10 @@ static struct addr_marker address_markers[] = {
 	{ 0,			"vmemmap start" },
 	{ 0,			"vmemmap end" },
 #endif
-	{ (unsigned long) PCI_IOBASE,		"PCI I/O start" },
-	{ (unsigned long) PCI_IOBASE + SZ_16M,	"PCI I/O end" },
 	{ FIXADDR_START,	"Fixmap start" },
 	{ FIXADDR_TOP,		"Fixmap end" },
+	{ PCI_IO_START,		"PCI I/O start" },
+	{ PCI_IO_END,		"PCI I/O end" },
 	{ MODULES_VADDR,	"Modules start" },
 	{ MODULES_END,		"Modules end" },
 	{ PAGE_OFFSET,		"Kernel Mapping" },

arch/arm64/mm/init.c

@@ -35,6 +35,7 @@
 #include <linux/efi.h>
 
 #include <asm/fixmap.h>
+#include <asm/memory.h>
 #include <asm/sections.h>
 #include <asm/setup.h>
 #include <asm/sizes.h>
@@ -296,8 +297,8 @@ void __init mem_init(void)
 		  "    vmemmap : 0x%16lx - 0x%16lx   (%6ld GB maximum)\n"
 		  "              0x%16lx - 0x%16lx   (%6ld MB actual)\n"
 #endif
-		  "    PCI I/O : 0x%16lx - 0x%16lx   (%6ld MB)\n"
 		  "    fixed   : 0x%16lx - 0x%16lx   (%6ld KB)\n"
+		  "    PCI I/O : 0x%16lx - 0x%16lx   (%6ld MB)\n"
 		  "    modules : 0x%16lx - 0x%16lx   (%6ld MB)\n"
 		  "    memory  : 0x%16lx - 0x%16lx   (%6ld MB)\n"
 		  "      .init : 0x%p" " - 0x%p" "   (%6ld KB)\n"
@@ -310,8 +311,8 @@ void __init mem_init(void)
 		  MLM((unsigned long)virt_to_page(PAGE_OFFSET),
 		      (unsigned long)virt_to_page(high_memory)),
 #endif
-		  MLM((unsigned long)PCI_IOBASE, (unsigned long)PCI_IOBASE + SZ_16M),
 		  MLK(FIXADDR_START, FIXADDR_TOP),
+		  MLM(PCI_IO_START, PCI_IO_END),
 		  MLM(MODULES_VADDR, MODULES_END),
 		  MLM(PAGE_OFFSET, (unsigned long)high_memory),
 		  MLK_ROUNDUP(__init_begin, __init_end),