4.20-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 634724431607f6f46c495dfef801a1c8b44a96d9 ]
Since __sanitizer_cov_trace_const_cmp4 is marked as notrace, the function called from __sanitizer_cov_trace_const_cmp4 shouldn't be traceable either. ftrace_graph_caller() gets called every time func write_comp_data() gets called if it isn't marked 'notrace'. This is the backtrace from gdb:
#0 ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:179 #1 0xffffff8010201920 in ftrace_caller () at ../arch/arm64/kernel/entry-ftrace.S:151 #2 0xffffff8010439714 in write_comp_data (type=5, arg1=0, arg2=0, ip=18446743524224276596) at ../kernel/kcov.c:116 #3 0xffffff8010439894 in __sanitizer_cov_trace_const_cmp4 (arg1=<optimized out>, arg2=<optimized out>) at ../kernel/kcov.c:188 #4 0xffffff8010201874 in prepare_ftrace_return (self_addr=18446743524226602768, parent=0xffffff801014b918, frame_pointer=18446743524223531344) at ./include/generated/atomic-instrumented.h:27 #5 0xffffff801020194c in ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:182
Rework so that write_comp_data() that are called from __sanitizer_cov_trace_*_cmp*() are marked as 'notrace'.
Commit 903e8ff86753 ("kernel/kcov.c: mark funcs in __sanitizer_cov_trace_pc() as notrace") missed to mark write_comp_data() as 'notrace'. When that patch was created gcc-7 was used. In lib/Kconfig.debug config KCOV_ENABLE_COMPARISONS depends on $(cc-option,-fsanitize-coverage=trace-cmp)
That code path isn't hit with gcc-7. However, it were that with gcc-8.
Link: http://lkml.kernel.org/r/20181206143011.23719-1-anders.roxell@linaro.org Signed-off-by: Anders Roxell anders.roxell@linaro.org Signed-off-by: Arnd Bergmann arnd@arndb.de Co-developed-by: Arnd Bergmann arnd@arndb.de Acked-by: Steven Rostedt (VMware) rostedt@goodmis.org Cc: Will Deacon will.deacon@arm.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/kcov.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/kcov.c b/kernel/kcov.c index 97959d7b77e2..c2277dbdbfb1 100644 --- a/kernel/kcov.c +++ b/kernel/kcov.c @@ -112,7 +112,7 @@ void notrace __sanitizer_cov_trace_pc(void) EXPORT_SYMBOL(__sanitizer_cov_trace_pc);
#ifdef CONFIG_KCOV_ENABLE_COMPARISONS -static void write_comp_data(u64 type, u64 arg1, u64 arg2, u64 ip) +static void notrace write_comp_data(u64 type, u64 arg1, u64 arg2, u64 ip) { struct task_struct *t; u64 *area;