The patch titled
Subject: kernel/kcov.c: mark write_comp_data() as notrace
has been added to the -mm tree. Its filename is
kernel-kcovc-mark-func-write_comp_data-as-notrace.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kernel-kcovc-mark-func-write_comp_data-as-notrace.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kernel-kcovc-mark-func-write_comp_data-as-notrace.patch
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------------------------------------------------------
From: Anders Roxell <anders.roxell@xxxxxxxxxx>
Subject: kernel/kcov.c: mark write_comp_data() as notrace
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@xxxxxxxxxx
Signed-off-by: Anders Roxell <anders.roxell@xxxxxxxxxx>
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Co-developed-by: Arnd Bergmann <arnd@xxxxxxxx>
Acked-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/kcov.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/kcov.c~kernel-kcovc-mark-func-write_comp_data-as-notrace
+++ a/kernel/kcov.c
@@ -112,7 +112,7 @@ void notrace __sanitizer_cov_trace_pc(vo
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;
_
Patches currently in -mm which might be from anders.roxell@xxxxxxxxxx are
writeback-dont-decrement-wb-refcnt-if-wb-bdi.patch
kernel-kcovc-mark-func-write_comp_data-as-notrace.patch
