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| author | Michael Ellerman <mpe@ellerman.id.au> | 2016-08-05 14:25:53 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-08-31 13:12:38 +0200 |
| commit | c012268b37db6b10b59dac9b7f45956cb9a8bcb2 (patch) | |
| tree | ab4afbfa1b160e0192b7a946562f2c717cb73828 /drivers/misc | |
| parent | 8c57cac1457f3125a5d13dc03635c0708c61bff0 (diff) | |
| download | linux-c012268b37db6b10b59dac9b7f45956cb9a8bcb2.tar.bz2 | |
lkdtm: Mark lkdtm_rodata_do_nothing() notrace
lkdtm_rodata_do_nothing() is an empty function which is generated in
order to test the non-executability of rodata.
Currently if function tracing is enabled then an mcount callsite will be
generated for lkdtm_rodata_do_nothing(), and it will appear in the list
of available functions for function tracing (available_filter_functions).
Given it's purpose purely as a test function, it seems preferable for
lkdtm_rodata_do_nothing() to be marked notrace, so it doesn't appear as
traceable.
This also avoids triggering a linker bug on powerpc:
https://sourceware.org/bugzilla/show_bug.cgi?id=20428
When the linker sees code that needs to generate a call stub, eg. a
branch to mcount(), it assumes the section is executable and
dereferences a NULL pointer leading to a linker segfault. Marking
lkdtm_rodata_do_nothing() notrace avoids triggering the bug because the
function contains no other function calls.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/misc')
| -rw-r--r-- | drivers/misc/lkdtm_rodata.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/misc/lkdtm_rodata.c b/drivers/misc/lkdtm_rodata.c index 166b1db3969f..3564477b8c2d 100644 --- a/drivers/misc/lkdtm_rodata.c +++ b/drivers/misc/lkdtm_rodata.c @@ -4,7 +4,7 @@ */ #include "lkdtm.h" -void lkdtm_rodata_do_nothing(void) +void notrace lkdtm_rodata_do_nothing(void) { /* Does nothing. We just want an architecture agnostic "return". */ } |