forked from Minki/linux
dce0e7d54a
Dynamic tracing of kernel modules is broken on 32-bit MIPS. When modules are loaded, the kernel crashes when dynamic tracing is enabled with: cd /sys/kernel/debug/tracing echo > set_ftrace_filter echo function > current_tracer 1) arch/mips/kernel/ftrace.c When the kernel boots, or when a module is initialized, ftrace_make_nop() modifies every _mcount call site to eliminate the ftrace overhead. However, when ftrace is later enabled for a call site, ftrace_make_call() does not currently restore the _mcount call correctly for module call sites. Added ftrace_modify_code_2r() and modified ftrace_make_call() to fix this. 2) arch/mips/kernel/mcount.S _mcount assembly routine is supposed to have the caller's _mcount call site address in register a0. However, a0 is currently not calculated correctly for module call sites. a0 should be (ra - 20) or (ra - 24), depending on whether the kernel was built with KBUILD_MCOUNT_RA_ADDRESS or not. This fix has been tested on Broadcom BMIPS5000 processor. Dynamic tracing now works for both built-in functions and module functions. Signed-off-by: Petri Gynther <pgynther@google.com> Cc: linux-mips@linux-mips.org Cc: rostedt@goodmis.org Cc: alcooperx@gmail.com Cc: cminyard@mvista.com Patchwork: https://patchwork.linux-mips.org/patch/7476/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org> |
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