mirror of https://github.com/xemu-project/xemu.git
43c64a093d
The function's stated contract is simple enough: "round down to the nearest power of 2". Suggests the domain is the representable numbers >= 1, because that's the smallest power of two. The implementation doesn't check for domain errors, but returns garbage instead: * For negative arguments, pow2floor() returns -2^63, which is not even a power of two, let alone the nearest one. What sort of works is passing *unsigned* arguments >= 2^63. The implicit conversion to signed is implementation defined, but commonly yields the (negative) two's complement. pow2floor() then returns -2^63. Callers that convert that back to unsigned get the correct value 2^63. * For a zero argument, pow2floor() shifts right by 64. Undefined behavior. Common actual behavior is to shift by 0, yielding -2^63. Fix by switching from int64_t to uint64_t and amending the contract to map zero to zero. Callers are fine with that: * memory_access_size() This function makes no sense unless the argument is positive and the return value fits into int. * raw_refresh_limits() Passes an int between 1 and BDRV_REQUEST_MAX_BYTES. * iscsi_refresh_limits() Passes an integer between 0 and INT_MAX, converts the result to uint32_t. Passing zero would be undefined behavior, but commonly yield zero. The patch gives us the zero without the undefined behavior. * cache_init() Passes a positive int64_t argument. * xbzrle_cache_resize() Passes a positive int64_t argument (>= TARGET_PAGE_SIZE, actually). * spapr_node0_size() Passes a positive uint64_t argument, and converts the result to hwaddr, i.e. uint64_t. * spapr_populate_memory() Passes a positive hwaddr argument, and converts the result to hwaddr. Cc: Juan Quintela <quintela@redhat.com> Cc: Dr. David Alan Gilbert <dgilbert@redhat.com> Cc: Eric Blake <eblake@redhat.com> Cc: Peter Maydell <peter.maydell@linaro.org> Cc: Alexey Kardashevskiy <aik@ozlabs.ru> Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <1501148776-16890-3-git-send-email-armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> |
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| .. | ||
| acl.h | ||
| atomic.h | ||
| base64.h | ||
| bcd.h | ||
| bitmap.h | ||
| bitops.h | ||
| bswap.h | ||
| buffer.h | ||
| compiler.h | ||
| config-file.h | ||
| coroutine.h | ||
| coroutine_int.h | ||
| cpuid.h | ||
| crc32c.h | ||
| cutils.h | ||
| envlist.h | ||
| error-report.h | ||
| event_notifier.h | ||
| fifo8.h | ||
| fifo32.h | ||
| fprintf-fn.h | ||
| futex.h | ||
| hbitmap.h | ||
| help_option.h | ||
| host-utils.h | ||
| id.h | ||
| int128.h | ||
| iov.h | ||
| jhash.h | ||
| log.h | ||
| main-loop.h | ||
| memfd.h | ||
| mmap-alloc.h | ||
| module.h | ||
| notify.h | ||
| option.h | ||
| option_int.h | ||
| osdep.h | ||
| path.h | ||
| processor.h | ||
| qdist.h | ||
| qht.h | ||
| queue.h | ||
| range.h | ||
| ratelimit.h | ||
| rcu.h | ||
| rcu_queue.h | ||
| readline.h | ||
| seqlock.h | ||
| sockets.h | ||
| stats64.h | ||
| systemd.h | ||
| thread-posix.h | ||
| thread-win32.h | ||
| thread.h | ||
| throttle-options.h | ||
| throttle.h | ||
| timed-average.h | ||
| timer.h | ||
| typedefs.h | ||
| unicode.h | ||
| uri.h | ||
| uuid.h | ||
| xattr.h | ||