kernel.git/arch/arm64/kernel/entry-ftrace.S, branch linux-4.5.y

arm64: ftrace: fix function_graph tracer panic

2015-10-02T10:12:56Z

When function graph tracer is enabled, the following operation will trigger panic: mount -t debugfs nodev /sys/kernel echo next_tgid > /sys/kernel/tracing/set_ftrace_filter echo function_graph > /sys/kernel/tracing/current_tracer ls /proc/ ------------[ cut here ]------------ [ 198.501417] Unable to handle kernel paging request at virtual address cb88537fdc8ba316 [ 198.506126] pgd = ffffffc008f79000 [ 198.509363] [cb88537fdc8ba316] *pgd=00000000488c6003, *pud=00000000488c6003, *pmd=0000000000000000 [ 198.517726] Internal error: Oops: 94000005 [#1] SMP [ 198.518798] Modules linked in: [ 198.520582] CPU: 1 PID: 1388 Comm: ls Tainted: G [ 198.521800] Hardware name: linux,dummy-virt (DT) [ 198.522852] task: ffffffc0fa9e8000 ti: ffffffc0f9ab0000 task.ti: ffffffc0f9ab0000 [ 198.524306] PC is at next_tgid+0x30/0x100 [ 198.525205] LR is at return_to_handler+0x0/0x20 [ 198.526090] pc : [] lr : [] pstate: 60000145 [ 198.527392] sp : ffffffc0f9ab3d40 [ 198.528084] x29: ffffffc0f9ab3d40 x28: ffffffc0f9ab0000 [ 198.529406] x27: ffffffc000d6a000 x26: ffffffc000b786e8 [ 198.530659] x25: ffffffc0002a1900 x24: ffffffc0faf16c00 [ 198.531942] x23: ffffffc0f9ab3ea0 x22: 0000000000000002 [ 198.533202] x21: ffffffc000d85050 x20: 0000000000000002 [ 198.534446] x19: 0000000000000002 x18: 0000000000000000 [ 198.535719] x17: 000000000049fa08 x16: ffffffc000242efc [ 198.537030] x15: 0000007fa472b54c x14: ffffffffff000000 [ 198.538347] x13: ffffffc0fada84a0 x12: 0000000000000001 [ 198.539634] x11: ffffffc0f9ab3d70 x10: ffffffc0f9ab3d70 [ 198.540915] x9 : ffffffc0000907c0 x8 : ffffffc0f9ab3d40 [ 198.542215] x7 : 0000002e330f08f0 x6 : 0000000000000015 [ 198.543508] x5 : 0000000000000f08 x4 : ffffffc0f9835ec0 [ 198.544792] x3 : cb88537fdc8ba316 x2 : cb88537fdc8ba306 [ 198.546108] x1 : 0000000000000002 x0 : ffffffc000d85050 [ 198.547432] [ 198.547920] Process ls (pid: 1388, stack limit = 0xffffffc0f9ab0020) [ 198.549170] Stack: (0xffffffc0f9ab3d40 to 0xffffffc0f9ab4000) [ 198.582568] Call trace: [ 198.583313] [] next_tgid+0x30/0x100 [ 198.584359] [] ftrace_graph_caller+0x6c/0x70 [ 198.585503] [] ftrace_graph_caller+0x6c/0x70 [ 198.586574] [] ftrace_graph_caller+0x6c/0x70 [ 198.587660] [] ftrace_graph_caller+0x6c/0x70 [ 198.588896] Code: aa0003f5 2a0103f4 b4000102 91004043 (885f7c60) [ 198.591092] ---[ end trace 6a346f8f20949ac8 ]--- This is because when using function graph tracer, if the traced function return value is in multi regs ([x0-x7]), return_to_handler may corrupt them. So in return_to_handler, the parameter regs should be protected properly. Cc: # 3.18+ Signed-off-by: Li Bin Acked-by: AKASHI Takahiro Signed-off-by: Catalin Marinas

arm64: ftrace: eliminate literal pool entries

2014-11-07T15:04:49Z

Replace ldr xN, = with adrp/add or adrp/ldr [as appropriate] in the implementation of _mcount(), which may be called very often. Signed-off-by: Ard Biesheuvel Signed-off-by: Will Deacon

arm64, ftrace: Remove check of obsolete variable function_trace_stop

2014-07-18T17:58:10Z

Nothing sets function_trace_stop to disable function tracing anymore. Remove the check for it in the arch code. arm64 was broken anyway, as it had an ifdef testing CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST which is only set if the arch supports the code (which it obviously did not), and it was testing a non existent ftrace_trace_stop instead of function_trace_stop. Link: http://lkml.kernel.org/r/20140627124421.GP26276@arm.com Cc: AKASHI Takahiro Acked-by: Will Deacon Signed-off-by: Steven Rostedt

arm64: ftrace: Fix comment typo 'CONFIG_FUNCTION_GRAPH_FP_TEST'

2014-06-18T11:40:52Z

Signed-off-by: Paul Bolle Signed-off-by: Catalin Marinas

arm64: ftrace: Add dynamic ftrace support

2014-05-29T08:08:33Z

This patch allows "dynamic ftrace" if CONFIG_DYNAMIC_FTRACE is enabled. Here we can turn on and off tracing dynamically per-function base. On arm64, this is done by patching single branch instruction to _mcount() inserted by gcc -pg option. The branch is replaced to NOP initially at kernel start up, and later on, NOP to branch to ftrace_caller() when enabled or branch to NOP when disabled. Please note that ftrace_caller() is a counterpart of _mcount() in case of 'static' ftrace. More details on architecture specific requirements are described in Documentation/trace/ftrace-design.txt. Acked-by: Will Deacon Signed-off-by: AKASHI Takahiro Signed-off-by: Will Deacon

arm64: Add ftrace support

2014-05-29T08:08:08Z

This patch implements arm64 specific part to support function tracers, such as function (CONFIG_FUNCTION_TRACER), function_graph (CONFIG_FUNCTION_GRAPH_TRACER) and function profiler (CONFIG_FUNCTION_PROFILER). With 'function' tracer, all the functions in the kernel are traced with timestamps in ${sysfs}/tracing/trace. If function_graph tracer is specified, call graph is generated. The kernel must be compiled with -pg option so that _mcount() is inserted at the beginning of functions. This function is called on every function's entry as long as tracing is enabled. In addition, function_graph tracer also needs to be able to probe function's exit. ftrace_graph_caller() & return_to_handler do this by faking link register's value to intercept function's return path. More details on architecture specific requirements are described in Documentation/trace/ftrace-design.txt. Reviewed-by: Ganapatrao Kulkarni Acked-by: Will Deacon Signed-off-by: AKASHI Takahiro Signed-off-by: Will Deacon