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author | Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | 2018-10-13 15:10:50 -0400 |
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committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2018-10-17 15:35:29 -0400 |
commit | 9c0be3f6b5d776dfe3ed249862c244a4486414dc (patch) | |
tree | 7bf3f3e4b90045293c299b0a7747adfe60e4b055 /kernel/tracepoint.c | |
parent | 62165600ae73ebd76e2d9b992b36360408d570d8 (diff) | |
download | linux-9c0be3f6b5d776dfe3ed249862c244a4486414dc.tar.gz linux-9c0be3f6b5d776dfe3ed249862c244a4486414dc.tar.bz2 linux-9c0be3f6b5d776dfe3ed249862c244a4486414dc.zip |
tracepoint: Fix tracepoint array element size mismatch
commit 46e0c9be206f ("kernel: tracepoints: add support for relative
references") changes the layout of the __tracepoint_ptrs section on
architectures supporting relative references. However, it does so
without turning struct tracepoint * const into const int elsewhere in
the tracepoint code, which has the following side-effect:
Setting mod->num_tracepoints is done in by module.c:
mod->tracepoints_ptrs = section_objs(info, "__tracepoints_ptrs",
sizeof(*mod->tracepoints_ptrs),
&mod->num_tracepoints);
Basically, since sizeof(*mod->tracepoints_ptrs) is a pointer size
(rather than sizeof(int)), num_tracepoints is erroneously set to half the
size it should be on 64-bit arch. So a module with an odd number of
tracepoints misses the last tracepoint due to effect of integer
division.
So in the module going notifier:
for_each_tracepoint_range(mod->tracepoints_ptrs,
mod->tracepoints_ptrs + mod->num_tracepoints,
tp_module_going_check_quiescent, NULL);
the expression (mod->tracepoints_ptrs + mod->num_tracepoints) actually
evaluates to something within the bounds of the array, but miss the
last tracepoint if the number of tracepoints is odd on 64-bit arch.
Fix this by introducing a new typedef: tracepoint_ptr_t, which
is either "const int" on architectures that have PREL32 relocations,
or "struct tracepoint * const" on architectures that does not have
this feature.
Also provide a new tracepoint_ptr_defer() static inline to
encapsulate deferencing this type rather than duplicate code and
ugly idefs within the for_each_tracepoint_range() implementation.
This issue appears in 4.19-rc kernels, and should ideally be fixed
before the end of the rc cycle.
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Jessica Yu <jeyu@kernel.org>
Link: http://lkml.kernel.org/r/20181013191050.22389-1-mathieu.desnoyers@efficios.com
Link: http://lkml.kernel.org/r/20180704083651.24360-7-ard.biesheuvel@linaro.org
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morris <james.morris@microsoft.com>
Cc: James Morris <jmorris@namei.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Nicolas Pitre <nico@linaro.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Thomas Garnier <thgarnie@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/tracepoint.c')
-rw-r--r-- | kernel/tracepoint.c | 24 |
1 files changed, 8 insertions, 16 deletions
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c index bf2c06ef9afc..a3be42304485 100644 --- a/kernel/tracepoint.c +++ b/kernel/tracepoint.c @@ -28,8 +28,8 @@ #include <linux/sched/task.h> #include <linux/static_key.h> -extern struct tracepoint * const __start___tracepoints_ptrs[]; -extern struct tracepoint * const __stop___tracepoints_ptrs[]; +extern tracepoint_ptr_t __start___tracepoints_ptrs[]; +extern tracepoint_ptr_t __stop___tracepoints_ptrs[]; DEFINE_SRCU(tracepoint_srcu); EXPORT_SYMBOL_GPL(tracepoint_srcu); @@ -371,25 +371,17 @@ int tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data) } EXPORT_SYMBOL_GPL(tracepoint_probe_unregister); -static void for_each_tracepoint_range(struct tracepoint * const *begin, - struct tracepoint * const *end, +static void for_each_tracepoint_range( + tracepoint_ptr_t *begin, tracepoint_ptr_t *end, void (*fct)(struct tracepoint *tp, void *priv), void *priv) { + tracepoint_ptr_t *iter; + if (!begin) return; - - if (IS_ENABLED(CONFIG_HAVE_ARCH_PREL32_RELOCATIONS)) { - const int *iter; - - for (iter = (const int *)begin; iter < (const int *)end; iter++) - fct(offset_to_ptr(iter), priv); - } else { - struct tracepoint * const *iter; - - for (iter = begin; iter < end; iter++) - fct(*iter, priv); - } + for (iter = begin; iter < end; iter++) + fct(tracepoint_ptr_deref(iter), priv); } #ifdef CONFIG_MODULES |