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![Eric W. Biederman](/assets/img/avatar_default.png)
Linus recently observed that if we did not worry about the padding member in struct siginfo it is only about 48 bytes, and 48 bytes is much nicer than 128 bytes for allocating on the stack and copying around in the kernel. The obvious thing of only adding the padding when userspace is including siginfo.h won't work as there are sigframe definitions in the kernel that embed struct siginfo. So split siginfo in two; kernel_siginfo and siginfo. Keeping the traditional name for the userspace definition. While the version that is used internally to the kernel and ultimately will not be padded to 128 bytes is called kernel_siginfo. The definition of struct kernel_siginfo I have put in include/signal_types.h A set of buildtime checks has been added to verify the two structures have the same field offsets. To make it easy to verify the change kernel_siginfo retains the same size as siginfo. The reduction in size comes in a following change. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
125 lines
3.4 KiB
C
125 lines
3.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#undef TRACE_SYSTEM
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#define TRACE_SYSTEM signal
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#if !defined(_TRACE_SIGNAL_H) || defined(TRACE_HEADER_MULTI_READ)
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#define _TRACE_SIGNAL_H
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#include <linux/signal.h>
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#include <linux/sched.h>
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#include <linux/tracepoint.h>
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#define TP_STORE_SIGINFO(__entry, info) \
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do { \
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if (info == SEND_SIG_NOINFO) { \
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__entry->errno = 0; \
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__entry->code = SI_USER; \
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} else if (info == SEND_SIG_PRIV) { \
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__entry->errno = 0; \
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__entry->code = SI_KERNEL; \
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} else { \
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__entry->errno = info->si_errno; \
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__entry->code = info->si_code; \
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} \
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} while (0)
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#ifndef TRACE_HEADER_MULTI_READ
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enum {
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TRACE_SIGNAL_DELIVERED,
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TRACE_SIGNAL_IGNORED,
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TRACE_SIGNAL_ALREADY_PENDING,
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TRACE_SIGNAL_OVERFLOW_FAIL,
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TRACE_SIGNAL_LOSE_INFO,
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};
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#endif
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/**
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* signal_generate - called when a signal is generated
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* @sig: signal number
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* @info: pointer to struct siginfo
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* @task: pointer to struct task_struct
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* @group: shared or private
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* @result: TRACE_SIGNAL_*
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*
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* Current process sends a 'sig' signal to 'task' process with
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* 'info' siginfo. If 'info' is SEND_SIG_NOINFO or SEND_SIG_PRIV,
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* 'info' is not a pointer and you can't access its field. Instead,
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* SEND_SIG_NOINFO means that si_code is SI_USER, and SEND_SIG_PRIV
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* means that si_code is SI_KERNEL.
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*/
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TRACE_EVENT(signal_generate,
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TP_PROTO(int sig, struct kernel_siginfo *info, struct task_struct *task,
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int group, int result),
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TP_ARGS(sig, info, task, group, result),
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TP_STRUCT__entry(
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__field( int, sig )
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__field( int, errno )
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__field( int, code )
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__array( char, comm, TASK_COMM_LEN )
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__field( pid_t, pid )
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__field( int, group )
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__field( int, result )
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),
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TP_fast_assign(
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__entry->sig = sig;
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TP_STORE_SIGINFO(__entry, info);
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memcpy(__entry->comm, task->comm, TASK_COMM_LEN);
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__entry->pid = task->pid;
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__entry->group = group;
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__entry->result = result;
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),
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TP_printk("sig=%d errno=%d code=%d comm=%s pid=%d grp=%d res=%d",
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__entry->sig, __entry->errno, __entry->code,
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__entry->comm, __entry->pid, __entry->group,
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__entry->result)
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);
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/**
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* signal_deliver - called when a signal is delivered
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* @sig: signal number
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* @info: pointer to struct siginfo
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* @ka: pointer to struct k_sigaction
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*
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* A 'sig' signal is delivered to current process with 'info' siginfo,
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* and it will be handled by 'ka'. ka->sa.sa_handler can be SIG_IGN or
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* SIG_DFL.
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* Note that some signals reported by signal_generate tracepoint can be
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* lost, ignored or modified (by debugger) before hitting this tracepoint.
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* This means, this can show which signals are actually delivered, but
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* matching generated signals and delivered signals may not be correct.
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*/
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TRACE_EVENT(signal_deliver,
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TP_PROTO(int sig, struct kernel_siginfo *info, struct k_sigaction *ka),
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TP_ARGS(sig, info, ka),
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TP_STRUCT__entry(
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__field( int, sig )
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__field( int, errno )
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__field( int, code )
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__field( unsigned long, sa_handler )
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__field( unsigned long, sa_flags )
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),
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TP_fast_assign(
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__entry->sig = sig;
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TP_STORE_SIGINFO(__entry, info);
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__entry->sa_handler = (unsigned long)ka->sa.sa_handler;
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__entry->sa_flags = ka->sa.sa_flags;
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),
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TP_printk("sig=%d errno=%d code=%d sa_handler=%lx sa_flags=%lx",
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__entry->sig, __entry->errno, __entry->code,
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__entry->sa_handler, __entry->sa_flags)
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);
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#endif /* _TRACE_SIGNAL_H */
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/* This part must be outside protection */
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#include <trace/define_trace.h>
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