[lttng-dev] [PATCH lttng-modules v6 5/5] Extract the payload of epoll_wait/epoll_pwait
Mathieu Desnoyers
mathieu.desnoyers at efficios.com
Sat Apr 30 14:22:22 UTC 2016
----- On Apr 29, 2016, at 6:53 PM, Julien Desfossez jdesfossez at efficios.com wrote:
> When epoll_wait returns, extract the content of the "events" field
> (events set and data payload).
>
> Here is an example output:
> syscall_entry_epoll_wait: { epfd = 3, maxevents = 32, timeout = 100 }
> syscall_exit_epoll_wait: { ret = 1, fds_length = 1,
> fds = [ [0] = { raw_events = 0x1,
> events = { EPOLLIN = 1, EPOLLPRI = 0, EPOLLOUT = 0, EPOLLERR = 0,
> padding = 0 },
> data_union = { u64 = 0x100000005, fd = 5 } } ]
> }
>
> Signed-off-by: Julien Desfossez <jdesfossez at efficios.com>
> ---
> .../syscalls/headers/syscalls_pointers_override.h | 179 +++++++++++++++++++++
> 1 file changed, 179 insertions(+)
>
> diff --git a/instrumentation/syscalls/headers/syscalls_pointers_override.h
> b/instrumentation/syscalls/headers/syscalls_pointers_override.h
> index 59931df..ceb1fab 100644
> --- a/instrumentation/syscalls/headers/syscalls_pointers_override.h
> +++ b/instrumentation/syscalls/headers/syscalls_pointers_override.h
> @@ -695,4 +695,183 @@ SC_LTTNG_TRACEPOINT_EVENT_CODE(epoll_ctl,
> )
> #endif /* defined(CONFIG_X86_32) || defined(CONFIG_X86_64) ||
> defined(CONFIG_ARM64) || defined(CONFIG_ARM) */
>
> +#ifndef ONCE_LTTNG_TRACE_EPOLL_H
> +#define ONCE_LTTNG_TRACE_EPOLL_H
> +
> +static struct lttng_event_field lttng_epoll_wait_fields[] = {
> + [0] = {
> + .name = "data_union",
> + .type = {
> + .atype = atype_struct,
> + .u._struct.nr_fields = ARRAY_SIZE(lttng_epoll_data_fields),
> + .u._struct.fields = lttng_epoll_data_fields,
> + }
> + },
> + [1] = {
> + .name = "raw_events",
> + .type = __type_integer(uint32_t, 0, 0, 0, __BYTE_ORDER, 16, none),
> + },
> + [2] = {
> + .name = "events",
> + .type = {
> + .atype = atype_struct,
> + .u._struct.nr_fields = ARRAY_SIZE(lttng_epoll_ctl_events_fields),
> + .u._struct.fields = lttng_epoll_ctl_events_fields,
> + }
> + },
> +};
> +
> +static struct lttng_type lttng_epoll_wait_elem = {
> + .atype = atype_struct,
> + .u._struct.nr_fields = ARRAY_SIZE(lttng_epoll_wait_fields),
> + .u._struct.fields = lttng_epoll_wait_fields,
> +};
> +
> +#endif /* ONCE_LTTNG_TRACE_EPOLL_H */
> +
> +#define LTTNG_SYSCALL_EPOLL_WAIT_locvar \
> + sc_out( \
> + unsigned int fds_length; \
> + uint8_t overflow; \
> + struct epoll_event *events; \
> + )
> +
> +#define LTTNG_SYSCALL_EPOLL_WAIT_code_pre \
> + BUILD_BUG_ON(((ARRAY_SIZE(lttng_epoll_ctl_events_fields) - 1) + \
> + EPOLL_FLAGS_PADDING_SIZE) != \
> + sizeof(uint8_t) * BITS_PER_BYTE); \
> + sc_out({ \
> + int err; \
> + unsigned long maxalloc; \
> + \
> + tp_locvar->fds_length = 0; \
> + tp_locvar->events = NULL; \
> + tp_locvar->overflow = 0; \
> + \
> + if (maxevents <= 0 || ret <= 0 || ret > maxevents) \
> + goto skip_code; \
> + \
> + if ((maxevents * sizeof(struct epoll_event)) > PAGE_SIZE) { \
change for
if (maxevents > PAGE_SIZE / sizeof(struct epoll_event))
to handle overflows.
> + maxalloc = PAGE_SIZE / sizeof(struct epoll_event); \
> + } else { \
> + maxalloc = maxevents; \
> + } \
> + \
> + if (ret > maxalloc) { \
> + tp_locvar->fds_length = maxalloc; \
> + tp_locvar->overflow = 1; \
> + } else { \
> + tp_locvar->fds_length = ret; \
> + } \
> + \
> + tp_locvar->events = kmalloc( \
> + maxalloc * sizeof(struct epoll_event), \
> + GFP_ATOMIC | GFP_NOWAIT); \
> + if (!tp_locvar->events) { \
> + tp_locvar->fds_length = 0; \
> + goto skip_code; \
> + } \
> + \
> + err = lib_ring_buffer_copy_from_user_check_nofault( \
> + tp_locvar->events, uevents, \
> + maxevents * sizeof(struct epoll_event)); \
> + if (err != 0) \
> + tp_locvar->fds_length = 0; \
> + } \
> + skip_code: \
> + )
> +
> +#define LTTNG_SYSCALL_EPOLL_WAIT_fds_field \
> + ctf_custom_field( \
> + ctf_custom_type( \
> + .atype = atype_sequence_compound, \
> + .u.sequence_compound.length_name = \
> + "fds_length", \
> + .u.sequence_compound.elem_type = \
> + <tng_epoll_wait_elem, \
> + ), \
> + fds, \
> + ctf_custom_code( \
> + uint32_t i; \
> + \
> + ctf_align(uint64_t) \
> + for (i = 0; i < tp_locvar->fds_length; i++) { \
> + ctf_integer_type(uint64_t, tp_locvar->events[i].data) \
> + ctf_integer_type(int, tp_locvar->events[i].data) \
> + ctf_integer_bitfield_type(uint32_t, \
> + cpu_to_le32(tp_locvar->events[i].events)) \
why LE, and why 32-bit rather than 16 ?
Thanks,
Mathieu
> + ctf_integer_bitfield_type(uint8_t, \
> + (uint8_t) tp_locvar->events[i].events) \
> + } \
> + ) \
> + )
> +
> +#define LTTNG_SYSCALL_EPOLL_WAIT_code_post \
> + sc_out( \
> + kfree(tp_locvar->events); \
> + )
> +
> +
> +#if defined(CONFIG_X86_32) || defined(CONFIG_X86_64)
> +#define OVERRIDE_32_epoll_wait
> +#define OVERRIDE_64_epoll_wait
> +SC_LTTNG_TRACEPOINT_EVENT_CODE(epoll_wait,
> + TP_PROTO(sc_exit(long ret,) int epfd, struct epoll_event __user * uevents,
> + int maxevents, int timeout),
> + TP_ARGS(sc_exit(ret,) epfd, uevents, maxevents, timeout),
> + TP_locvar(
> + LTTNG_SYSCALL_EPOLL_WAIT_locvar
> + ),
> + TP_code_pre(
> + LTTNG_SYSCALL_EPOLL_WAIT_code_pre
> + ),
> + TP_FIELDS(
> + sc_exit(ctf_integer(long, ret, ret))
> + sc_in(ctf_integer(int, epfd, epfd))
> + sc_in(ctf_integer(int, maxevents, maxevents))
> + sc_in(ctf_integer(int, timeout, timeout))
> + sc_out(ctf_integer(unsigned int, fds_length, tp_locvar->fds_length))
> + sc_out(ctf_integer(uint8_t, overflow, tp_locvar->overflow))
> + sc_out(
> + LTTNG_SYSCALL_EPOLL_WAIT_fds_field
> + )
> + ),
> + TP_code_post(
> + LTTNG_SYSCALL_EPOLL_WAIT_code_post
> + )
> +)
> +#endif /* defined(CONFIG_X86_32) || defined(CONFIG_X86_64) */
> +
> +#if defined(CONFIG_X86_32) || defined(CONFIG_X86_64) || defined(CONFIG_ARM64)
> || defined(CONFIG_ARM)
> +#define OVERRIDE_32_epoll_pwait
> +#define OVERRIDE_64_epoll_pwait
> +SC_LTTNG_TRACEPOINT_EVENT_CODE(epoll_pwait,
> + TP_PROTO(sc_exit(long ret,) int epfd, struct epoll_event __user * uevents,
> + int maxevents, int timeout, const sigset_t __user * sigmask, size_t
> sigsetsize),
> + TP_ARGS(sc_exit(ret,) epfd, uevents, maxevents, timeout, sigmask, sigsetsize),
> + TP_locvar(
> + LTTNG_SYSCALL_EPOLL_WAIT_locvar
> + ),
> + TP_code_pre(
> + LTTNG_SYSCALL_EPOLL_WAIT_code_pre
> + ),
> + TP_FIELDS(
> + sc_exit(ctf_integer(long, ret, ret))
> + sc_in(ctf_integer(int, epfd, epfd))
> + sc_in(ctf_integer(int, maxevents, maxevents))
> + sc_in(ctf_integer(int, timeout, timeout))
> + sc_in(ctf_integer_hex(const sigset_t *, sigmask, sigmask))
> + sc_in(ctf_integer(size_t, sigsetsize, sigsetsize))
> + sc_out(ctf_integer(unsigned int, fds_length, tp_locvar->fds_length))
> + sc_out(ctf_integer(uint8_t, overflow, tp_locvar->overflow))
> + sc_out(
> + LTTNG_SYSCALL_EPOLL_WAIT_fds_field
> + )
> + ),
> + TP_code_post(
> + LTTNG_SYSCALL_EPOLL_WAIT_code_post
> + )
> +)
> +#endif /* defined(CONFIG_X86_32) || defined(CONFIG_X86_64) ||
> defined(CONFIG_ARM64) || defined(CONFIG_ARM) */
> +
> #endif /* CREATE_SYSCALL_TABLE */
> --
> 1.9.1
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
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