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author | H.J. Lu <hjl.tools@gmail.com> | 2020-04-13 10:31:26 -0700 |
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committer | H.J. Lu <hjl.tools@gmail.com> | 2020-04-13 10:31:26 -0700 |
commit | df76ff3a446a787a95cf74cb15c285464d73a93d (patch) | |
tree | fb802ff931d65d7ee81b2425c7d26a4372cd81b6 /time/tst-getdate.c | |
parent | 319d2a7b60cc0d06bb5c29684c23475d41a7f8b7 (diff) | |
download | glibc-df76ff3a446a787a95cf74cb15c285464d73a93d.tar.gz glibc-df76ff3a446a787a95cf74cb15c285464d73a93d.tar.xz glibc-df76ff3a446a787a95cf74cb15c285464d73a93d.zip |
x32: Properly pass long to syscall [BZ #25810]
X32 has 32-bit long and pointer with 64-bit off_t. Since x32 psABI requires that pointers passed in registers must be zero-extended to 64bit, x32 can share many syscall interfaces with LP64. When a LP64 syscall with long and unsigned long arguments is used for x32, these arguments must be properly extended to 64-bit. Otherwise if the upper 32 bits of the register have undefined value, such a syscall will be rejected by kernel. Enforce zero-extension for pointers and array system call arguments. For integer types, extend to int64_t (the full register) using a regular cast, resulting in zero or sign extension based on the signedness of the original type. For void *mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset); we now generate 0: 41 f7 c1 ff 0f 00 00 test $0xfff,%r9d 7: 75 1f jne 28 <__mmap64+0x28> 9: 48 63 d2 movslq %edx,%rdx c: 89 f6 mov %esi,%esi e: 4d 63 c0 movslq %r8d,%r8 11: 4c 63 d1 movslq %ecx,%r10 14: b8 09 00 00 40 mov $0x40000009,%eax 19: 0f 05 syscall That is 1. addr is unchanged. 2. length is zero-extend to 64 bits. 3. prot is sign-extend to 64 bits. 4. flags is sign-extend to 64 bits. 5. fd is sign-extend to 64 bits. 6. offset is unchanged. For int arguments, since kernel uses only the lower 32 bits and ignores the upper 32 bits in 64-bit registers, these work correctly. Tested on x86-64 and x32. There are no code changes on x86-64.
Diffstat (limited to 'time/tst-getdate.c')
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