Use run-time page size where it matters

In AArch64, pages may be 4K or 64K depending on kernel configuration.
The GNU C Library documentation suggests [1], "the correct interface
to query about the page size is sysconf". Introduce one new
architecture-specific function-like macro, page_size(), that on x86
and AArch32 remains a constant so as to minimally affect performance,
but on AArch64 is sysconf(_SC_PAGESIZE) for correctness.

1. https://www.gnu.org/software/libc/manual/html_node/Query-Memory-Parameters.html

To minimize churn, the PAGE_SIZE macro is left as a build-time
estimation of what the run-time page size might be.

This fixes the following errors for CRIU on AArch64 kernels with
CONFIG_ARM64_64K_PAGES=y, allowing dump of
`setsid sleep < /dev/null &> /dev/null` to succeed.

Error (kerndat.c:48): Can't stat self map_files: No such file or directory

Error (util.c:668): Can't read pme for pid 90: No such file or directory

Error (parasite-syscall.c:1135): Can't open 89/map_files/0x3ffb7da0000-0x3ffb7dac000 on procfs: No such file or directory

Signed-off-by: Christopher Covington <cov@codeaurora.org>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

arch/aarch64/include/asm/page.h

@@ -0,0 +1,19 @@
+#ifndef __CR_ASM_PAGE_H__
+#define __CR_ASM_PAGE_H__
+
+#ifndef PAGE_SHIFT
+# define PAGE_SHIFT	12
+#endif
+
+#ifndef PAGE_SIZE
+# define PAGE_SIZE	(1UL << PAGE_SHIFT)
+#endif
+
+#ifndef PAGE_MASK
+# define PAGE_MASK	(~(PAGE_SIZE - 1))
+#endif
+
+#define PAGE_PFN(addr)	((addr) / PAGE_SIZE)
+#define page_size()	sysconf(_SC_PAGESIZE)
+
+#endif /* __CR_ASM_PAGE_H__ */

arch/aarch64/include/asm/types.h

@@ -6,7 +6,7 @@
 #include <asm/ptrace.h>
 #include "protobuf/core.pb-c.h"
 
-#include "asm-generic/page.h"
+#include "asm/page.h"
 #include "asm/bitops.h"
 #include "asm/int.h"
 

arch/arm/include/asm/page.h

@@ -1,5 +1,5 @@
-#ifndef __CR_ASM_GENERIC_PAGE_H__
+#ifndef __CR_ASM_PAGE_H__
-#define __CR_ASM_GENERIC_PAGE_H__
+#define __CR_ASM_PAGE_H__
 
 #ifndef PAGE_SHIFT
 # define PAGE_SHIFT	12
@@ -14,5 +14,6 @@
 #endif
 
 #define PAGE_PFN(addr)	((addr) / PAGE_SIZE)
+#define page_size()	PAGE_SIZE
 
-#endif /* __CR_ASM_GENERIC_PAGE_H__ */
+#endif /* __CR_ASM_PAGE_H__ */

arch/arm/include/asm/types.h

@@ -5,7 +5,7 @@
 #include <signal.h>
 #include "protobuf/core.pb-c.h"
 
-#include "asm-generic/page.h"
+#include "asm/page.h"
 #include "asm/bitops.h"
 #include "asm/int.h"
 

arch/x86/include/asm/page.h

@@ -0,0 +1,19 @@
+#ifndef __CR_ASM_PAGE_H__
+#define __CR_ASM_PAGE_H__
+
+#ifndef PAGE_SHIFT
+# define PAGE_SHIFT	12
+#endif
+
+#ifndef PAGE_SIZE
+# define PAGE_SIZE	(1UL << PAGE_SHIFT)
+#endif
+
+#ifndef PAGE_MASK
+# define PAGE_MASK	(~(PAGE_SIZE - 1))
+#endif
+
+#define PAGE_PFN(addr)	((addr) / PAGE_SIZE)
+#define page_size()	PAGE_SIZE
+
+#endif /* __CR_ASM_PAGE_H__ */

arch/x86/include/asm/types.h

@@ -4,7 +4,7 @@
 #include <stdbool.h>
 #include <signal.h>
 
-#include "asm-generic/page.h"
+#include "asm/page.h"
 #include "asm/bitops.h"
 #include "asm/int.h"
 #include "asm/prlimit.h"

bfd.c

@@ -13,7 +13,7 @@
 #include "list.h"
 #include "util.h"
 #include "xmalloc.h"
-#include "asm-generic/page.h"
+#include "asm/page.h"
 
 #undef	LOG_PREFIX
 #define LOG_PREFIX "bfd: "

include/pagemap-cache.h

@@ -2,7 +2,7 @@
 #define __CR_PAGEMAP_H__
 
 #include <sys/types.h>
-#include "asm-generic/page.h"
+#include "asm/page.h"
 #include "asm/int.h"
 
 #include "list.h"

kerndat.c

@@ -42,7 +42,7 @@ static int kerndat_get_shmemdev(void)
 	}
 
 	sprintf(maps, "/proc/self/map_files/%lx-%lx",
-			(unsigned long)map, (unsigned long)map + PAGE_SIZE);
+			(unsigned long)map, (unsigned long)map + page_size());
 	if (stat(maps, &buf) < 0) {
 		munmap(map, PAGE_SIZE);
 		pr_perror("Can't stat self map_files");

parasite-syscall.c

@@ -1129,7 +1129,7 @@ int parasite_map_exchange(struct parasite_ctl *ctl, unsigned long size)
 		return -1;
 	}
 
-	ctl->map_length = round_up(size, PAGE_SIZE);
+	ctl->map_length = round_up(size, page_size());
 
 	fd = open_proc_rw(ctl->pid.real, "map_files/%p-%p",
 		 ctl->remote_map, ctl->remote_map + ctl->map_length);

util.c

@@ -657,7 +657,7 @@ int vaddr_to_pfn(unsigned long vaddr, u64 *pfn)
 	if (fd < 0)
 		return -1;
 
-	off = (vaddr / PAGE_SIZE) * sizeof(u64);
+	off = (vaddr / page_size()) * sizeof(u64);
 	if (lseek(fd, off, SEEK_SET) != off) {
 		pr_perror("Failed to seek address %lx", vaddr);
 		goto out;