| Message ID | 20240206162801.882585-6-mjeanson@efficios.com |
|---|---|
| State | New |
| Headers | show |
| Series | Extend rseq support | expand |
Michael Jeanson <mjeanson@efficios.com> writes: > Implement internal rseq utils in preparation for their use in > rseq_load32_load32_relaxed(). > > This implementation is imported from the librseq project. *Which* librseq project, and what are the copyright/license terms of that project? I assume this has been discussed and approved before, but for archival reasons, that URL should be listed here explicitly, along with some note of the copyright clearance. > diff --git a/sysdeps/unix/sysv/linux/rseq-internal.h b/sysdeps/unix/sysv/linux/rseq-internal.h > +/* > + * gcc prior to 4.8.2 miscompiles asm goto. > + * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670 > + * > + * gcc prior to 8.1.0 miscompiles asm goto at O1. > + * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103908 > + * > + * clang prior to version 13.0.1 miscompiles asm goto at O2. > + * https://github.com/llvm/llvm-project/issues/52735 > + * > + * Work around these issues by adding a volatile inline asm with > + * memory clobber in the fallthrough after the asm goto and at each > + * label target. Emit this for all compilers in case other similar > + * issues are found in the future. > + */ > +#define rseq_after_asm_goto() __asm__ __volatile__ ("" : : : "memory") Ok. > +#define __rseq_str_1(x) #x > +#define __rseq_str(x) __rseq_str_1(x) Ok. > +/* Offset of rseq_cs field in struct rseq. */ > +#define RSEQ_CS_OFFSET 8 Ok. > +#define rseq_sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER)) > +#define rseq_offsetofend(TYPE, MEMBER) \ > + (offsetof(TYPE, MEMBER) + rseq_sizeof_field(TYPE, MEMBER)) Technically offsetofjustafterend, but ok ;-) > +/* Returns the int value of 'rseq_area->cpu_id'. */ > +static inline int > +rseq_get_cpu_id(void) > +{ > + return (int) RSEQ_GETMEM_VOLATILE (rseq_get_area(), cpu_id); > +} Ok. > +/* Returns true if the rseq registration is active. */ > +static inline bool > +rseq_is_registered(void) > +{ > + return rseq_get_cpu_id() >= 0; > +} Ok, REGISTRATION_FAILED is -2 > +/* Returns true if the current rseq registration has the 'node_id' field. */ > +static inline bool > +rseq_node_id_available(void) > +{ > + return __rseq_feature_size >= rseq_offsetofend(struct rseq_area, node_id); > +} Ok. > +/* Returns true if the current rseq registration has the 'mm_cid' field. */ > +static inline bool > +rseq_mm_cid_available(void) > +{ > + return __rseq_feature_size >= rseq_offsetofend(struct rseq_area, mm_cid); > +} Ok.
On 2024-02-16 21:33, DJ Delorie wrote: > Michael Jeanson <mjeanson@efficios.com> writes: >> Implement internal rseq utils in preparation for their use in >> rseq_load32_load32_relaxed(). >> >> This implementation is imported from the librseq project. > > *Which* librseq project, and what are the copyright/license terms of > that project? I assume this has been discussed and approved before, but > for archival reasons, that URL should be listed here explicitly, along > with some note of the copyright clearance. For reference, here is the URL to the librseq project : https://git.kernel.org/pub/scm/libs/librseq/librseq.git I'll double check the copyright clearance and licensing before sending the next patchset.
diff --git a/sysdeps/unix/sysv/linux/rseq-internal.h b/sysdeps/unix/sysv/linux/rseq-internal.h index a63e4afbdb..b6c29c14cc 100644 --- a/sysdeps/unix/sysv/linux/rseq-internal.h +++ b/sysdeps/unix/sysv/linux/rseq-internal.h @@ -41,12 +41,68 @@ struct rseq_area uint32_t mm_cid; }; +/* + * gcc prior to 4.8.2 miscompiles asm goto. + * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670 + * + * gcc prior to 8.1.0 miscompiles asm goto at O1. + * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103908 + * + * clang prior to version 13.0.1 miscompiles asm goto at O2. + * https://github.com/llvm/llvm-project/issues/52735 + * + * Work around these issues by adding a volatile inline asm with + * memory clobber in the fallthrough after the asm goto and at each + * label target. Emit this for all compilers in case other similar + * issues are found in the future. + */ +#define rseq_after_asm_goto() __asm__ __volatile__ ("" : : : "memory") + +#define __rseq_str_1(x) #x +#define __rseq_str(x) __rseq_str_1(x) + +/* Offset of rseq_cs field in struct rseq. */ +#define RSEQ_CS_OFFSET 8 + +#define rseq_sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER)) +#define rseq_offsetofend(TYPE, MEMBER) \ + (offsetof(TYPE, MEMBER) + rseq_sizeof_field(TYPE, MEMBER)) + +/* Returns a pointer to the current thread rseq area. */ static inline struct rseq_area * rseq_get_area(void) { return (struct rseq_area *) ((char *) __thread_pointer() + GLRO (dl_tls_rseq_offset)); } +/* Returns the int value of 'rseq_area->cpu_id'. */ +static inline int +rseq_get_cpu_id(void) +{ + return (int) RSEQ_GETMEM_VOLATILE (rseq_get_area(), cpu_id); +} + +/* Returns true if the rseq registration is active. */ +static inline bool +rseq_is_registered(void) +{ + return rseq_get_cpu_id() >= 0; +} + +/* Returns true if the current rseq registration has the 'node_id' field. */ +static inline bool +rseq_node_id_available(void) +{ + return __rseq_feature_size >= rseq_offsetofend(struct rseq_area, node_id); +} + +/* Returns true if the current rseq registration has the 'mm_cid' field. */ +static inline bool +rseq_mm_cid_available(void) +{ + return __rseq_feature_size >= rseq_offsetofend(struct rseq_area, mm_cid); +} + #ifdef RSEQ_SIG static inline bool rseq_register_current_thread (struct pthread *self, bool do_rseq)