[PATCH kexec-tools 01/32] kdump: mmap() and munmap() only work on page-aligned quantites
From: Russell King <hidden>
Date: 2016-05-03 10:21:08
Also in:
kexec
Subsystem:
the rest · Maintainer:
Linus Torvalds
The man page for mmap() and munmap() says that mmap() and munmap() only works for page-aligned addresses, sizes and offsets. Arrange to give these interfaces what they want. Signed-off-by: Russell King <redacted> --- kdump/kdump.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-)
diff --git a/kdump/kdump.c b/kdump/kdump.c
index 821ee7c..3247a54 100644
--- a/kdump/kdump.c
+++ b/kdump/kdump.c@@ -25,22 +25,35 @@ #define MAP_WINDOW_SIZE (64*1024*1024) #define DEV_MEM "/dev/mem" +#define ALIGN_MASK(x,y) (((x) + (y)) & ~(y)) +#define ALIGN(x,y) ALIGN_MASK(x, (y) - 1) + static void *map_addr(int fd, unsigned long size, off_t offset) { + unsigned long page_size = getpagesize(); + unsigned long map_offset = offset & (page_size - 1); + size_t len = ALIGN(size + map_offset, page_size); void *result; - result = mmap(0, size, PROT_READ, MAP_SHARED, fd, offset); + + result = mmap(0, len, PROT_READ, MAP_SHARED, fd, offset - map_offset); if (result == MAP_FAILED) { fprintf(stderr, "Cannot mmap " DEV_MEM " offset: %llu size: %lu: %s\n", (unsigned long long)offset, size, strerror(errno)); exit(5); } - return result; + return result + map_offset; } static void unmap_addr(void *addr, unsigned long size) { + unsigned long page_size = getpagesize(); + unsigned long map_offset = (uintptr_t)addr & (page_size - 1); + size_t len = ALIGN(size + map_offset, page_size); int ret; - ret = munmap(addr, size); + + addr -= map_offset; + + ret = munmap(addr, len); if (ret < 0) { fprintf(stderr, "munmap failed: %s\n", strerror(errno));
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1.9.1