On Fri, 10 Aug 2018 18:02:23 +0200 (CEST) Torsten Duwe <duwe@xxxxxx> wrote: > --- a/arch/arm64/kernel/entry-ftrace.S > +++ b/arch/arm64/kernel/entry-ftrace.S > @@ -13,6 +13,8 @@ > #include <asm/assembler.h> > #include <asm/ftrace.h> > #include <asm/insn.h> > +#include <asm/asm-offsets.h> > +#include <asm/assembler.h> > > /* > * Gcc with -pg will put the following code in the beginning of each function: > @@ -123,6 +125,7 @@ skip_ftrace_call: // } > ENDPROC(_mcount) > > #else /* CONFIG_DYNAMIC_FTRACE */ > +#ifndef CONFIG_DYNAMIC_FTRACE_WITH_REGS > /* > * _mcount() is used to build the kernel with -pg option, but all the branch > * instructions to _mcount() are replaced to NOP initially at kernel start up, > @@ -162,6 +165,84 @@ ftrace_graph_call: // ftrace_graph_cal > > mcount_exit > ENDPROC(ftrace_caller) > +#else /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */ > +ENTRY(_mcount) > + mov x10, lr > + mov lr, x9 > + ret x10 > +ENDPROC(_mcount) > + > +ENTRY(ftrace_caller) > + stp x29, x9, [sp, #-16]! > + sub sp, sp, #S_FRAME_SIZE > + > + stp x0, x1, [sp] > + stp x2, x3, [sp, #16] > + stp x4, x5, [sp, #32] > + stp x6, x7, [sp, #48] > + stp x8, x9, [sp, #64] > + stp x10, x11, [sp, #80] > + stp x12, x13, [sp, #96] > + stp x14, x15, [sp, #112] > + stp x16, x17, [sp, #128] > + stp x18, x19, [sp, #144] > + stp x20, x21, [sp, #160] > + stp x22, x23, [sp, #176] > + stp x24, x25, [sp, #192] > + stp x26, x27, [sp, #208] > + stp x28, x29, [sp, #224] Wait! You are having ftrace_caller *always* perform the regs save? Why? This is why I have a ftrace_caller and a ftrace_regs_caller, so that normal function tracing doesn't take the overhead hit of tracing all functions. And note, the generic code will differentiate per function. The regs calling is usually only done for a handful of functions, the normal tracing of all functions doesn't need it. Or am I missing something? > + /* The link Register at callee entry */ > + str x9, [sp, #S_LR] > + /* The program counter just after the ftrace call site */ > + str lr, [sp, #S_PC] > + /* The stack pointer as it was on ftrace_caller entry... */ > + add x29, sp, #S_FRAME_SIZE+16 /* ...is also our new FP */ > + str x29, [sp, #S_SP] > + > + adrp x0, function_trace_op > + ldr x2, [x0, #:lo12:function_trace_op] > + mov x1, x9 /* saved LR == parent IP */ > + sub x0, lr, #8 /* function entry == IP */ > + mov x3, sp /* complete pt_regs are @sp */ > + > + .global ftrace_call > +ftrace_call: > + > + bl ftrace_stub > + > +#ifdef CONFIG_FUNCTION_GRAPH_TRACER > + .global ftrace_graph_call > +ftrace_graph_call: // ftrace_graph_caller(); > + nop // If enabled, this will be replaced > + // "b ftrace_graph_caller" > +#endif > + > +ftrace_regs_return: > + ldp x0, x1, [sp] > + ldp x2, x3, [sp, #16] > + ldp x4, x5, [sp, #32] > + ldp x6, x7, [sp, #48] > + ldp x8, x9, [sp, #64] > + ldp x10, x11, [sp, #80] > + ldp x12, x13, [sp, #96] > + ldp x14, x15, [sp, #112] > + ldp x16, x17, [sp, #128] > + ldp x18, x19, [sp, #144] > + ldp x20, x21, [sp, #160] > + ldp x22, x23, [sp, #176] > + ldp x24, x25, [sp, #192] > + ldp x26, x27, [sp, #208] > + ldp x28, x29, [sp, #224] > + > + ldr x9, [sp, #S_PC] > + ldr lr, [sp, #S_LR] > + add sp, sp, #S_FRAME_SIZE+16 > + > + ret x9 > + > +ENDPROC(ftrace_caller) > + > +#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */ > #endif /* CONFIG_DYNAMIC_FTRACE */ > > ENTRY(ftrace_stub) > @@ -197,12 +278,20 @@ ENDPROC(ftrace_stub) > * and run return_to_handler() later on its exit. > */ > ENTRY(ftrace_graph_caller) > +#ifndef CONFIG_DYNAMIC_FTRACE_WITH_REGS > mcount_get_lr_addr x0 // pointer to function's saved lr > mcount_get_pc x1 // function's pc > mcount_get_parent_fp x2 // parent's fp > bl prepare_ftrace_return // prepare_ftrace_return(&lr, pc, fp) > > mcount_exit > +#else > + add x0, sp, #S_LR /* address of (LR pointing into caller) */ > + ldr x1, [sp, #S_PC] > + ldr x2, [sp, #232] /* caller's frame pointer */ > + bl prepare_ftrace_return > + b ftrace_regs_return > +#endif > ENDPROC(ftrace_graph_caller) >
