Fix: Remove start and number from syscall_get_arguments() args (v5.1)

  commit b35f549df1d7520d37ba1e6d4a8d4df6bd52d136
  Author: Steven Rostedt (Red Hat) <rostedt@goodmis.org>
  Date:   Mon Nov 7 16:26:37 2016 -0500

    syscalls: Remove start and number from syscall_get_arguments() args

    At Linux Plumbers, Andy Lutomirski approached me and pointed out that the
    function call syscall_get_arguments() implemented in x86 was horribly
    written and not optimized for the standard case of passing in 0 and 6 for
    the starting index and the number of system calls to get. When looking at
    all the users of this function, I discovered that all instances pass in only
    0 and 6 for these arguments. Instead of having this function handle
    different cases that are never used, simply rewrite it to return the first 6
    arguments of a system call.

    This should help out the performance of tracing system calls by ptrace,
    ftrace and perf.

Link: http://lkml.kernel.org/r/20161107213233.754809394@goodmis.org
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/lttng-syscalls.c b/lttng-syscalls.c
index bcc06b5cd03759db0334756b3433e806c58e3093..ebd9246c32ef8b4e0ce1c469d1876b443166d67f 100644 (file)
--- a/lttng-syscalls.c
+++ b/lttng-syscalls.c
@@ -25,6 +25,7 @@
 #include <wrapper/tracepoint.h>
 #include <wrapper/file.h>
 #include <wrapper/rcu.h>
+#include <wrapper/syscall.h>
 #include <lttng-events.h>
 
 #ifndef CONFIG_COMPAT
@@ -361,9 +362,9 @@ struct lttng_syscall_filter {
 static void syscall_entry_unknown(struct lttng_event *event,
        struct pt_regs *regs, unsigned int id)
 {
-       unsigned long args[UNKNOWN_SYSCALL_NRARGS];
+       unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
-       syscall_get_arguments(current, regs, 0, UNKNOWN_SYSCALL_NRARGS, args);
+       lttng_syscall_get_arguments(current, regs, args);
        if (unlikely(in_compat_syscall()))
                __event_probe__compat_syscall_entry_unknown(event, id, args);
        else
@@ -432,9 +433,9 @@ void syscall_entry_probe(void *__data, struct pt_regs *regs, long id)
        case 1:
        {
                void (*fptr)(void *__data, unsigned long arg0) = entry->func;
-               unsigned long args[1];
+               unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
-               syscall_get_arguments(current, regs, 0, entry->nrargs, args);
+               lttng_syscall_get_arguments(current, regs, args);
                fptr(event, args[0]);
                break;
        }
@@ -443,9 +444,9 @@ void syscall_entry_probe(void *__data, struct pt_regs *regs, long id)
                void (*fptr)(void *__data,
                        unsigned long arg0,
                        unsigned long arg1) = entry->func;
-               unsigned long args[2];
+               unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
-               syscall_get_arguments(current, regs, 0, entry->nrargs, args);
+               lttng_syscall_get_arguments(current, regs, args);
                fptr(event, args[0], args[1]);
                break;
        }
@@ -455,9 +456,9 @@ void syscall_entry_probe(void *__data, struct pt_regs *regs, long id)
                        unsigned long arg0,
                        unsigned long arg1,
                        unsigned long arg2) = entry->func;
-               unsigned long args[3];
+               unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
-               syscall_get_arguments(current, regs, 0, entry->nrargs, args);
+               lttng_syscall_get_arguments(current, regs, args);
                fptr(event, args[0], args[1], args[2]);
                break;
        }
@@ -468,9 +469,9 @@ void syscall_entry_probe(void *__data, struct pt_regs *regs, long id)
                        unsigned long arg1,
                        unsigned long arg2,
                        unsigned long arg3) = entry->func;
-               unsigned long args[4];
+               unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
-               syscall_get_arguments(current, regs, 0, entry->nrargs, args);
+               lttng_syscall_get_arguments(current, regs, args);
                fptr(event, args[0], args[1], args[2], args[3]);
                break;
        }
@@ -482,9 +483,9 @@ void syscall_entry_probe(void *__data, struct pt_regs *regs, long id)
                        unsigned long arg2,
                        unsigned long arg3,
                        unsigned long arg4) = entry->func;
-               unsigned long args[5];
+               unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
-               syscall_get_arguments(current, regs, 0, entry->nrargs, args);
+               lttng_syscall_get_arguments(current, regs, args);
                fptr(event, args[0], args[1], args[2], args[3], args[4]);
                break;
        }
@@ -497,9 +498,9 @@ void syscall_entry_probe(void *__data, struct pt_regs *regs, long id)
                        unsigned long arg3,
                        unsigned long arg4,
                        unsigned long arg5) = entry->func;
-               unsigned long args[6];
+               unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
-               syscall_get_arguments(current, regs, 0, entry->nrargs, args);
+               lttng_syscall_get_arguments(current, regs, args);
                fptr(event, args[0], args[1], args[2],
                        args[3], args[4], args[5]);
                break;
@@ -512,9 +513,9 @@ void syscall_entry_probe(void *__data, struct pt_regs *regs, long id)
 static void syscall_exit_unknown(struct lttng_event *event,
        struct pt_regs *regs, int id, long ret)
 {
-       unsigned long args[UNKNOWN_SYSCALL_NRARGS];
+       unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
-       syscall_get_arguments(current, regs, 0, UNKNOWN_SYSCALL_NRARGS, args);
+       lttng_syscall_get_arguments(current, regs, args);
        if (unlikely(in_compat_syscall()))
                __event_probe__compat_syscall_exit_unknown(event, id, ret,
                        args);
@@ -588,9 +589,9 @@ void syscall_exit_probe(void *__data, struct pt_regs *regs, long ret)
                void (*fptr)(void *__data,
                        long ret,
                        unsigned long arg0) = entry->func;
-               unsigned long args[1];
+               unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
-               syscall_get_arguments(current, regs, 0, entry->nrargs, args);
+               lttng_syscall_get_arguments(current, regs, args);
                fptr(event, ret, args[0]);
                break;
        }
@@ -600,9 +601,9 @@ void syscall_exit_probe(void *__data, struct pt_regs *regs, long ret)
                        long ret,
                        unsigned long arg0,
                        unsigned long arg1) = entry->func;
-               unsigned long args[2];
+               unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
-               syscall_get_arguments(current, regs, 0, entry->nrargs, args);
+               lttng_syscall_get_arguments(current, regs, args);
                fptr(event, ret, args[0], args[1]);
                break;
        }
@@ -613,9 +614,9 @@ void syscall_exit_probe(void *__data, struct pt_regs *regs, long ret)
                        unsigned long arg0,
                        unsigned long arg1,
                        unsigned long arg2) = entry->func;
-               unsigned long args[3];
+               unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
-               syscall_get_arguments(current, regs, 0, entry->nrargs, args);
+               lttng_syscall_get_arguments(current, regs, args);
                fptr(event, ret, args[0], args[1], args[2]);
                break;
        }
@@ -627,9 +628,9 @@ void syscall_exit_probe(void *__data, struct pt_regs *regs, long ret)
                        unsigned long arg1,
                        unsigned long arg2,
                        unsigned long arg3) = entry->func;
-               unsigned long args[4];
+               unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
-               syscall_get_arguments(current, regs, 0, entry->nrargs, args);
+               lttng_syscall_get_arguments(current, regs, args);
                fptr(event, ret, args[0], args[1], args[2], args[3]);
                break;
        }
@@ -642,9 +643,9 @@ void syscall_exit_probe(void *__data, struct pt_regs *regs, long ret)
                        unsigned long arg2,
                        unsigned long arg3,
                        unsigned long arg4) = entry->func;
-               unsigned long args[5];
+               unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
-               syscall_get_arguments(current, regs, 0, entry->nrargs, args);
+               lttng_syscall_get_arguments(current, regs, args);
                fptr(event, ret, args[0], args[1], args[2], args[3], args[4]);
                break;
        }
@@ -658,9 +659,9 @@ void syscall_exit_probe(void *__data, struct pt_regs *regs, long ret)
                        unsigned long arg3,
                        unsigned long arg4,
                        unsigned long arg5) = entry->func;
-               unsigned long args[6];
+               unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
-               syscall_get_arguments(current, regs, 0, entry->nrargs, args);
+               lttng_syscall_get_arguments(current, regs, args);
                fptr(event, ret, args[0], args[1], args[2],
                        args[3], args[4], args[5]);
                break;

diff --git a/wrapper/syscall.h b/wrapper/syscall.h
new file mode 100644 (file)
index 0000000..8715f0c
--- /dev/null
+++ b/wrapper/syscall.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
+ *
+ * wrapper/syscall.h
+ *
+ * wrapper around asm/syscall.h.
+ *
+ * Copyright (C) 2019 Michael Jeanson <mjeanson@efficios.com>
+ */
+
+#ifndef _LTTNG_WRAPPER_SYSCALL_H
+#define _LTTNG_WRAPPER_SYSCALL_H
+
+#include <asm/syscall.h>
+#include <lttng-kernel-version.h>
+
+#define LTTNG_SYSCALL_NR_ARGS 6
+
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,1,0))
+
+#define lttng_syscall_get_arguments(task, regs, args) \
+       syscall_get_arguments(task, regs, args)
+
+#else /* LINUX_VERSION_CODE >= KERNEL_VERSION(5,1,0) */
+
+static inline
+void lttng_syscall_get_arguments(struct task_struct *task,
+               struct pt_regs *regs, unsigned long *args)
+{
+       syscall_get_arguments(task, regs, 0, LTTNG_SYSCALL_NR_ARGS, args);
+}
+
+#endif /* LINUX_VERSION_CODE >= KERNEL_VERSION(5,1,0) */
+
+#endif /* _LTTNG_WRAPPER_SYSCALL_H */