Messages in this thread | | | Date | Sat, 19 Oct 2002 22:51:49 -0600 | From | Erik Andersen <> | Subject | Re: [PATCH] work around duff ABIs |
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On Sun Oct 20, 2002 at 05:31:47AM +0100, Matthew Wilcox wrote: > > *sigh*. i hate this kind of bullshit. please, don't anyone ever try > to pass 64-bit args through the syscall interface again.
I agree it can be a pain.
[-----------snip-------------] > -asmlinkage ssize_t sys_pread64(unsigned int fd, char *buf, > - size_t count, loff_t pos) > +#ifdef __BIG_ENDIAN > +asmlinkage ssize_t sys_pread64(unsigned int fd, char *buf, size_t count, > + unsigned int high, unsigned int low) > +#else > +asmlinkage ssize_t sys_pread64(unsigned int fd, char *buf, size_t count, > + unsigned int low, unsigned int high) > +#endif
Nonono. Please see __LONG_LONG_PAIR in /usr/include/endian.h. Your user space code should be doing something like this:
static inline _syscall5(ssize_t, __syscall_pread, int, fd, void *, buf, size_t, count, off_t, offset_hi, off_t, offset_lo);
ssize_t __libc_pread(int fd, void *buf, size_t count, off_t offset) { return(__syscall_pread(fd,buf,count,__LONG_LONG_PAIR((off_t)0,offset))); }
ssize_t __libc_pread64(int fd, void *buf, size_t count, off64_t offset) { return(__syscall_pread(fd, buf, count, __LONG_LONG_PAIR((off_t)(offset>>32), (off_t)(offset&0xffffffff)))); }
Your patch is going to break GNU libc, uClibc, and anyone else in userspace that is doing pread and pread64 correctly....
-Erik
-- Erik B. Andersen http://codepoet-consulting.com/ --This message was written using 73% post-consumer electrons-- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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