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posix: Fix large mmap64 offset for mips64n32 (BZ#24699)

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The fix for BZ#21270 (commit 158d5fa0e1) added a mask to avoid offset larger
than 1^44 to be used along __NR_mmap2.  However mips64n32 users __NR_mmap,
as mips64n64, but still defines off_t as old non-LFS type (other ILP32, such
x32, defines off_t being equal to off64_t).  This leads to use the same
mask meant only for __NR_mmap2 call for __NR_mmap, thus limiting the maximum
offset it can use with mmap64.

This patch fixes by setting the high mask only for __NR_mmap2 usage. The
posix/tst-mmap-offset.c already tests it and also fails for mips64n32. The
patch also change the test to check for an arch-specific header that defines
the maximum supported offset.

Checked on x86_64-linux-gnu, i686-linux-gnu, and I also tests tst-mmap-offset
on qemu simulated mips64 with kernel 3.2.0 kernel for both mips-linux-gnu and
mips64-n32-linux-gnu.

	[BZ #24699]
	* posix/tst-mmap-offset.c: Mention BZ #24699.
	(do_test_bz21270): Rename to do_test_large_offset and use
	mmap64_maximum_offset to check for maximum expected offset value.
	* sysdeps/generic/mmap_info.h: New file.
	* sysdeps/unix/sysv/linux/mips/mmap_info.h: Likewise.
	* sysdeps/unix/sysv/linux/mmap64.c (MMAP_OFF_HIGH_MASK): Define iff
	__NR_mmap2 is used.
This commit is contained in:
Adhemerval Zanella
2019-06-18 14:09:09 -03:00
parent 99135114ba
commit a008c76b56
5 changed files with 53 additions and 5 deletions
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9
sysdeps/unix/sysv/linux/mmap64.c
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@ -23,11 +23,18 @@
#include <sysdep.h>
#include <mmap_internal.h>
#ifdef __NR_mmap2
/* To avoid silent truncation of offset when using mmap2, do not accept
offset larger than 1 << (page_shift + off_t bits). For archictures with
32 bits off_t and page size of 4096 it would be 1^44. */
#define MMAP_OFF_HIGH_MASK \
# define MMAP_OFF_HIGH_MASK \
((-(MMAP2_PAGE_UNIT << 1) << (8 * sizeof (off_t) - 1)))
#else
/* Some ABIs might use __NR_mmap while having sizeof (off_t) smaller than
sizeof (off64_t) (currently only MIPS64n32). For this case just set
zero the higher bits so mmap with large offset does not fail. */
# define MMAP_OFF_HIGH_MASK 0x0
#endif
#define MMAP_OFF_MASK (MMAP_OFF_HIGH_MASK | MMAP_OFF_LOW_MASK)