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Mathieu Desnoyers
9c0be3f6b5
commit 46e0c9be20 ("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 <[email protected]>
Acked-by: Jessica Yu <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Cc: Michael Ellerman <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Bjorn Helgaas <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: James Morris <[email protected]>
Cc: James Morris <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Nicolas Pitre <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Petr Mladek <[email protected]>
Cc: Russell King <[email protected]>
Cc: "Serge E. Hallyn" <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Thomas Garnier <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Mathieu Desnoyers <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>
51 lines
1.0 KiB
C
51 lines
1.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef TRACEPOINT_DEFS_H
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#define TRACEPOINT_DEFS_H 1
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/*
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* File can be included directly by headers who only want to access
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* tracepoint->key to guard out of line trace calls, or the definition of
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* trace_print_flags{_u64}. Otherwise linux/tracepoint.h should be used.
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*/
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#include <linux/atomic.h>
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#include <linux/static_key.h>
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struct trace_print_flags {
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unsigned long mask;
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const char *name;
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};
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struct trace_print_flags_u64 {
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unsigned long long mask;
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const char *name;
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};
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struct tracepoint_func {
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void *func;
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void *data;
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int prio;
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};
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struct tracepoint {
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const char *name; /* Tracepoint name */
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struct static_key key;
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int (*regfunc)(void);
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void (*unregfunc)(void);
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struct tracepoint_func __rcu *funcs;
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};
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#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
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typedef const int tracepoint_ptr_t;
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#else
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typedef struct tracepoint * const tracepoint_ptr_t;
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#endif
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struct bpf_raw_event_map {
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struct tracepoint *tp;
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void *bpf_func;
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u32 num_args;
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} __aligned(32);
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#endif
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