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| author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2019-10-15 09:00:55 -0400 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2019-11-14 13:13:43 -0500 |
| commit | b83b43ffc6e4b514ca034a0fbdee01322e2f7022 (patch) | |
| tree | 8e8d830664e6faf98589f241bd0ccba44802f8c8 /include | |
| parent | 953ae45a0c25e09428d4a03d7654f97ab8a36647 (diff) | |
| download | linux-b83b43ffc6e4b514ca034a0fbdee01322e2f7022.tar.gz linux-b83b43ffc6e4b514ca034a0fbdee01322e2f7022.tar.bz2 linux-b83b43ffc6e4b514ca034a0fbdee01322e2f7022.zip | |
fgraph: Fix function type mismatches of ftrace_graph_return using ftrace_stub
The C compiler is allowing more checks to make sure that function pointers
are assigned to the correct prototype function. Unfortunately, the function
graph tracer uses a special name with its assigned ftrace_graph_return
function pointer that maps to a stub function used by the function tracer
(ftrace_stub). The ftrace_graph_return variable is compared to the
ftrace_stub in some archs to know if the function graph tracer is enabled or
not. This means we can not just simply create a new function stub that
compares it without modifying all the archs.
Instead, have the linker script create a function_graph_stub that maps to
ftrace_stub, and this way we can define the prototype for it to match the
prototype of ftrace_graph_return, and make the compiler checks all happy!
Link: http://lkml.kernel.org/r/20191015090055.789a0aed@gandalf.local.home
Cc: linux-sh@vger.kernel.org
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Reported-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/asm-generic/vmlinux.lds.h | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index dae64600ccbf..0f358be551cd 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -111,18 +111,29 @@ #ifdef CONFIG_FTRACE_MCOUNT_RECORD #ifdef CC_USING_PATCHABLE_FUNCTION_ENTRY +/* + * Need to also make ftrace_graph_stub point to ftrace_stub + * so that the same stub location may have different protocols + * and not mess up with C verifiers. + */ #define MCOUNT_REC() . = ALIGN(8); \ __start_mcount_loc = .; \ KEEP(*(__patchable_function_entries)) \ - __stop_mcount_loc = .; + __stop_mcount_loc = .; \ + ftrace_graph_stub = ftrace_stub; #else #define MCOUNT_REC() . = ALIGN(8); \ __start_mcount_loc = .; \ KEEP(*(__mcount_loc)) \ - __stop_mcount_loc = .; + __stop_mcount_loc = .; \ + ftrace_graph_stub = ftrace_stub; #endif #else -#define MCOUNT_REC() +# ifdef CONFIG_FUNCTION_TRACER +# define MCOUNT_REC() ftrace_graph_stub = ftrace_stub; +# else +# define MCOUNT_REC() +# endif #endif #ifdef CONFIG_TRACE_BRANCH_PROFILING |