| Message ID | 20201209160956.32456-3-jgross@suse.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | xen: support per-cpupool scheduling granularity | expand |
On 09.12.2020 17:09, Juergen Gross wrote: > --- a/xen/include/xen/guest_access.h > +++ b/xen/include/xen/guest_access.h > @@ -26,6 +26,11 @@ > type *_x = (hnd).p; \ > (XEN_GUEST_HANDLE_PARAM(type)) { _x }; \ > }) > +/* Same for casting to a const type. */ > +#define guest_handle_const_cast(hnd, type) ({ \ > + const type *_x = (const type *)((hnd).p); \ > + (XEN_GUEST_HANDLE_PARAM(const_##type)) { _x }; \ > +}) Afaict this allow casting from e.g. uint to const_ulong. We don't want to permit this (i.e. if really needed one is to go through two steps). I think all it takes is dropping the cast: #define guest_handle_const_cast(hnd, type) ({ \ const type *_x = (hnd).p; \ (XEN_GUEST_HANDLE_PARAM(const_##type)) { _x }; \ }) With this Reviewed-by: Jan Beulich <jbeulich@suse.com> and I'd be okay making the adjustment while committing (provided it works and I didn't overlook anything). Jan
On 16.12.20 17:08, Jan Beulich wrote: > On 09.12.2020 17:09, Juergen Gross wrote: >> --- a/xen/include/xen/guest_access.h >> +++ b/xen/include/xen/guest_access.h >> @@ -26,6 +26,11 @@ >> type *_x = (hnd).p; \ >> (XEN_GUEST_HANDLE_PARAM(type)) { _x }; \ >> }) >> +/* Same for casting to a const type. */ >> +#define guest_handle_const_cast(hnd, type) ({ \ >> + const type *_x = (const type *)((hnd).p); \ >> + (XEN_GUEST_HANDLE_PARAM(const_##type)) { _x }; \ >> +}) > > Afaict this allow casting from e.g. uint to const_ulong. We > don't want to permit this (i.e. if really needed one is to > go through two steps). I think all it takes is dropping the > cast: > > #define guest_handle_const_cast(hnd, type) ({ \ > const type *_x = (hnd).p; \ > (XEN_GUEST_HANDLE_PARAM(const_##type)) { _x }; \ > }) > > With this > Reviewed-by: Jan Beulich <jbeulich@suse.com> > and I'd be okay making the adjustment while committing > (provided it works and I didn't overlook anything). At least it is still compiling, and I guess that was the main concern. Juergen
On 16.12.2020 17:17, Jürgen Groß wrote: > On 16.12.20 17:08, Jan Beulich wrote: >> On 09.12.2020 17:09, Juergen Gross wrote: >>> --- a/xen/include/xen/guest_access.h >>> +++ b/xen/include/xen/guest_access.h >>> @@ -26,6 +26,11 @@ >>> type *_x = (hnd).p; \ >>> (XEN_GUEST_HANDLE_PARAM(type)) { _x }; \ >>> }) >>> +/* Same for casting to a const type. */ >>> +#define guest_handle_const_cast(hnd, type) ({ \ >>> + const type *_x = (const type *)((hnd).p); \ >>> + (XEN_GUEST_HANDLE_PARAM(const_##type)) { _x }; \ >>> +}) >> >> Afaict this allow casting from e.g. uint to const_ulong. We >> don't want to permit this (i.e. if really needed one is to >> go through two steps). I think all it takes is dropping the >> cast: >> >> #define guest_handle_const_cast(hnd, type) ({ \ >> const type *_x = (hnd).p; \ >> (XEN_GUEST_HANDLE_PARAM(const_##type)) { _x }; \ >> }) >> >> With this >> Reviewed-by: Jan Beulich <jbeulich@suse.com> >> and I'd be okay making the adjustment while committing >> (provided it works and I didn't overlook anything). > > At least it is still compiling, and I guess that was the main > concern. Indeed. Thanks for checking. Jan
diff --git a/xen/common/hypfs.c b/xen/common/hypfs.c index 2e8e90591e..6f822ae097 100644 --- a/xen/common/hypfs.c +++ b/xen/common/hypfs.c @@ -344,7 +344,8 @@ static int hypfs_read(const struct hypfs_entry *entry, } int hypfs_write_leaf(struct hypfs_entry_leaf *leaf, - XEN_GUEST_HANDLE_PARAM(void) uaddr, unsigned int ulen) + XEN_GUEST_HANDLE_PARAM(const_void) uaddr, + unsigned int ulen) { char *buf; int ret; @@ -384,7 +385,8 @@ int hypfs_write_leaf(struct hypfs_entry_leaf *leaf, } int hypfs_write_bool(struct hypfs_entry_leaf *leaf, - XEN_GUEST_HANDLE_PARAM(void) uaddr, unsigned int ulen) + XEN_GUEST_HANDLE_PARAM(const_void) uaddr, + unsigned int ulen) { bool buf; @@ -405,7 +407,8 @@ int hypfs_write_bool(struct hypfs_entry_leaf *leaf, } int hypfs_write_custom(struct hypfs_entry_leaf *leaf, - XEN_GUEST_HANDLE_PARAM(void) uaddr, unsigned int ulen) + XEN_GUEST_HANDLE_PARAM(const_void) uaddr, + unsigned int ulen) { struct param_hypfs *p; char *buf; @@ -439,13 +442,15 @@ int hypfs_write_custom(struct hypfs_entry_leaf *leaf, } int hypfs_write_deny(struct hypfs_entry_leaf *leaf, - XEN_GUEST_HANDLE_PARAM(void) uaddr, unsigned int ulen) + XEN_GUEST_HANDLE_PARAM(const_void) uaddr, + unsigned int ulen) { return -EACCES; } static int hypfs_write(struct hypfs_entry *entry, - XEN_GUEST_HANDLE_PARAM(void) uaddr, unsigned long ulen) + XEN_GUEST_HANDLE_PARAM(const_void) uaddr, + unsigned long ulen) { struct hypfs_entry_leaf *l; @@ -497,7 +502,7 @@ long do_hypfs_op(unsigned int cmd, break; case XEN_HYPFS_OP_write_contents: - ret = hypfs_write(entry, arg3, arg4); + ret = hypfs_write(entry, guest_handle_const_cast(arg3, void), arg4); break; default: diff --git a/xen/include/xen/guest_access.h b/xen/include/xen/guest_access.h index f9b94cf1f4..5a50c3ccee 100644 --- a/xen/include/xen/guest_access.h +++ b/xen/include/xen/guest_access.h @@ -26,6 +26,11 @@ type *_x = (hnd).p; \ (XEN_GUEST_HANDLE_PARAM(type)) { _x }; \ }) +/* Same for casting to a const type. */ +#define guest_handle_const_cast(hnd, type) ({ \ + const type *_x = (const type *)((hnd).p); \ + (XEN_GUEST_HANDLE_PARAM(const_##type)) { _x }; \ +}) /* Cast a XEN_GUEST_HANDLE to XEN_GUEST_HANDLE_PARAM */ #define guest_handle_to_param(hnd, type) ({ \ diff --git a/xen/include/xen/hypfs.h b/xen/include/xen/hypfs.h index 53f50772b4..99fd4b036d 100644 --- a/xen/include/xen/hypfs.h +++ b/xen/include/xen/hypfs.h @@ -38,7 +38,7 @@ struct hypfs_funcs { int (*read)(const struct hypfs_entry *entry, XEN_GUEST_HANDLE_PARAM(void) uaddr); int (*write)(struct hypfs_entry_leaf *leaf, - XEN_GUEST_HANDLE_PARAM(void) uaddr, unsigned int ulen); + XEN_GUEST_HANDLE_PARAM(const_void) uaddr, unsigned int ulen); unsigned int (*getsize)(const struct hypfs_entry *entry); struct hypfs_entry *(*findentry)(const struct hypfs_entry_dir *dir, const char *name, unsigned int name_len); @@ -154,13 +154,17 @@ int hypfs_read_dir(const struct hypfs_entry *entry, int hypfs_read_leaf(const struct hypfs_entry *entry, XEN_GUEST_HANDLE_PARAM(void) uaddr); int hypfs_write_deny(struct hypfs_entry_leaf *leaf, - XEN_GUEST_HANDLE_PARAM(void) uaddr, unsigned int ulen); + XEN_GUEST_HANDLE_PARAM(const_void) uaddr, + unsigned int ulen); int hypfs_write_leaf(struct hypfs_entry_leaf *leaf, - XEN_GUEST_HANDLE_PARAM(void) uaddr, unsigned int ulen); + XEN_GUEST_HANDLE_PARAM(const_void) uaddr, + unsigned int ulen); int hypfs_write_bool(struct hypfs_entry_leaf *leaf, - XEN_GUEST_HANDLE_PARAM(void) uaddr, unsigned int ulen); + XEN_GUEST_HANDLE_PARAM(const_void) uaddr, + unsigned int ulen); int hypfs_write_custom(struct hypfs_entry_leaf *leaf, - XEN_GUEST_HANDLE_PARAM(void) uaddr, unsigned int ulen); + XEN_GUEST_HANDLE_PARAM(const_void) uaddr, + unsigned int ulen); unsigned int hypfs_getsize(const struct hypfs_entry *entry); struct hypfs_entry *hypfs_leaf_findentry(const struct hypfs_entry_dir *dir, const char *name,
The node specific write functions take a void user address handle as parameter. As a write won't change the user memory use a const_void handle instead. This requires a new macro for casting a guest handle to a const type. Suggested-by: Jan Beulich <jbeulich@suse.com> Signed-off-by: Juergen Gross <jgross@suse.com> --- V3: - new patch --- xen/common/hypfs.c | 17 +++++++++++------ xen/include/xen/guest_access.h | 5 +++++ xen/include/xen/hypfs.h | 14 +++++++++----- 3 files changed, 25 insertions(+), 11 deletions(-)