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: I1235c32c5cf03612bf9c36785cf7c4f8f49d292b

diff --git a/src/lttng-syscalls.c b/src/lttng-syscalls.c
index 2fb6eda314390cefc10529a37332aaad6848f7d8..9cb0537a3e8b0e2ea38a4c5b42fcc3340d26f9b2 100644 (file)
--- a/src/lttng-syscalls.c
+++ b/src/lttng-syscalls.c
@@ -241,6 +241,12 @@ void syscall_entry_event_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 = syscall_table->sc_filter;
 
@@ -419,6 +425,12 @@ void syscall_exit_event_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())) {