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userfaultfd: enhance UFFDIO_API ioctl decoder

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It may return API and features even with errno set to EINVAL.

* userfaultfd.c (print_uffdio_api_start): New function.
(uffdio_ioctl): Decode api and features fields on exiting if errno
is EINVAL.
This commit is contained in:
Eugene Syromyatnikov 2018-09-11 06:05:08 +02:00
parent 22ec7c5edb
commit 399a2d8849
1 changed files with 29 additions and 13 deletions
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42
userfaultfd.c
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@ -64,6 +64,14 @@ tprintf_uffdio_range(const struct uffdio_range *range)
tprintf_uffdio_range(&(where_).field_); \
} while (0)
void
print_uffdio_api_start(struct uffdio_api *ua)
{
PRINT_FIELD_X("{", *ua, api);
PRINT_FIELD_FLAGS(", ", *ua, features, uffd_api_features,
"UFFD_FEATURE_???");
}
int
uffdio_ioctl(struct tcb *const tcp, const unsigned int code,
const kernel_ulong_t arg)
@ -77,9 +85,7 @@ uffdio_ioctl(struct tcb *const tcp, const unsigned int code,
tprints(", ");
if (umove_or_printaddr(tcp, arg, &ua))
break;
PRINT_FIELD_X("{", ua, api);
PRINT_FIELD_FLAGS(", ", ua, features, uffd_api_features,
"UFFD_FEATURE_???");
print_uffdio_api_start(&ua);
entering_features = malloc(sizeof(*entering_features));
if (entering_features) {
*entering_features = ua.features;
@ -89,18 +95,28 @@ uffdio_ioctl(struct tcb *const tcp, const unsigned int code,
return 0;
}
if (!syserror(tcp) && !umove(tcp, arg, &ua)) {
entering_features = get_tcb_priv_data(tcp);
if (!umove(tcp, arg, &ua)) {
/* UFFDIO_API can return -EINVAL if api or features
* do not match. */
if (syserror(tcp)) {
if (tcp->u_error == EINVAL) {
tprints("} => ");
print_uffdio_api_start(&ua);
}
} else {
entering_features = get_tcb_priv_data(tcp);
if (!entering_features
|| *entering_features != ua.features) {
PRINT_FIELD_FLAGS(" => ", ua, features,
uffd_api_features,
"UFFD_FEATURE_???");
if (!entering_features
|| *entering_features != ua.features) {
PRINT_FIELD_FLAGS(" => ", ua, features,
uffd_api_features,
"UFFD_FEATURE_???");
}
PRINT_FIELD_FLAGS(", ", ua, ioctls,
uffd_api_flags,
"_UFFDIO_???");
}
PRINT_FIELD_FLAGS(", ", ua, ioctls, uffd_api_flags,
"_UFFDIO_???");
}
tprints("}");