Explicitly skip tracing x32 system calls

x86 x32 system calls are not supported by LTTng. They are currently not
traced simply because their system call number is beyond the range of
NR_compat_syscalls.

However, this mostly happens by accident rather than by design.

Enforce this with an explicit check for in_x32_syscall(), which clearly
documents that those are not supported.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I3a6985a8355f14f4e557ee7f5edea36969dadfe9

diff --git a/lttng-syscalls.c b/lttng-syscalls.c
index 4596ccfc1280f82eaefdd0b5b6462bceffee0f8f..3399c9b07de90dcc39cc0a28fe69f0fdb4079eea 100644 (file)
--- a/lttng-syscalls.c
+++ b/lttng-syscalls.c
@@ -392,6 +392,12 @@ void syscall_entry_probe(void *__data, struct pt_regs *regs, long id)
        const struct trace_syscall_entry *table, *entry;
        size_t table_len;
 
+#ifdef CONFIG_X86_X32_ABI
+       if (in_x32_syscall()) {
+               /* x32 system calls are not supported. */
+               return;
+       }
+#endif
        if (unlikely(in_compat_syscall())) {
                struct lttng_syscall_filter *filter = chan->sc_filter;
 
@@ -539,6 +545,12 @@ void syscall_exit_probe(void *__data, struct pt_regs *regs, long ret)
        size_t table_len;
        long id;
 
+#ifdef CONFIG_X86_X32_ABI
+       if (in_x32_syscall()) {
+               /* x32 system calls are not supported. */
+               return;
+       }
+#endif
        id = syscall_get_nr(current, regs);
        if (unlikely(in_compat_syscall())) {
                struct lttng_syscall_filter *filter = chan->sc_filter;