mirror of git://sourceware.org/git/glibc.git
df76ff3a44
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.
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|---|---|---|
| .. | ||
| 64 | ||
| x32 | ||
| Implies | ||
| Makefile | ||
| Versions | ||
| ____longjmp_chk.S | ||
| __start_context.S | ||
| brk.c | ||
| clone.S | ||
| compat-timer.h | ||
| configure | ||
| configure.ac | ||
| dl-cache.h | ||
| dl-procinfo.c | ||
| dl-procinfo.h | ||
| getcontext.S | ||
| kernel-features.h | ||
| kernel_stat.h | ||
| ldconfig.h | ||
| ldd-rewrite.sed | ||
| libmvec.abilist | ||
| makecontext.c | ||
| pthread_setaffinity.c | ||
| readelflib.c | ||
| register-dump.h | ||
| sched_setaffinity.c | ||
| setcontext.S | ||
| sigaction.c | ||
| sigaltstack-offsets.sym | ||
| sigcontextinfo.h | ||
| swapcontext.S | ||
| syscall.S | ||
| syscalls.list | ||
| sysdep.S | ||
| sysdep.h | ||
| timer_create.c | ||
| timer_delete.c | ||
| timer_getoverr.c | ||
| timer_gettime.c | ||
| timer_settime.c | ||
| ucontext_i.sym | ||
| vfork.S | ||