diff options
Diffstat (limited to 'arch/arm64/kernel/entry-ftrace.S')
| -rw-r--r-- | arch/arm64/kernel/entry-ftrace.S | 133 |
1 files changed, 110 insertions, 23 deletions
diff --git a/arch/arm64/kernel/entry-ftrace.S b/arch/arm64/kernel/entry-ftrace.S index 3b625f76ffba..025140caafe7 100644 --- a/arch/arm64/kernel/entry-ftrace.S +++ b/arch/arm64/kernel/entry-ftrace.S @@ -36,6 +36,31 @@ SYM_CODE_START(ftrace_caller) bti c +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS + /* + * The literal pointer to the ops is at an 8-byte aligned boundary + * which is either 12 or 16 bytes before the BL instruction in the call + * site. See ftrace_call_adjust() for details. + * + * Therefore here the LR points at `literal + 16` or `literal + 20`, + * and we can find the address of the literal in either case by + * aligning to an 8-byte boundary and subtracting 16. We do the + * alignment first as this allows us to fold the subtraction into the + * LDR. + */ + bic x11, x30, 0x7 + ldr x11, [x11, #-(4 * AARCH64_INSN_SIZE)] // op + +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS + /* + * If the op has a direct call, handle it immediately without + * saving/restoring registers. + */ + ldr x17, [x11, #FTRACE_OPS_DIRECT_CALL] // op->direct_call + cbnz x17, ftrace_caller_direct +#endif +#endif + /* Save original SP */ mov x10, sp @@ -49,6 +74,10 @@ SYM_CODE_START(ftrace_caller) stp x6, x7, [sp, #FREGS_X6] str x8, [sp, #FREGS_X8] +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS + str xzr, [sp, #FREGS_DIRECT_TRAMP] +#endif + /* Save the callsite's FP, LR, SP */ str x29, [sp, #FREGS_FP] str x9, [sp, #FREGS_LR] @@ -65,13 +94,22 @@ SYM_CODE_START(ftrace_caller) stp x29, x30, [sp, #FREGS_SIZE] add x29, sp, #FREGS_SIZE - sub x0, x30, #AARCH64_INSN_SIZE // ip (callsite's BL insn) - mov x1, x9 // parent_ip (callsite's LR) - ldr_l x2, function_trace_op // op - mov x3, sp // regs + /* Prepare arguments for the tracer func */ + sub x0, x30, #AARCH64_INSN_SIZE // ip (callsite's BL insn) + mov x1, x9 // parent_ip (callsite's LR) + mov x3, sp // regs + +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS + mov x2, x11 // op + ldr x4, [x2, #FTRACE_OPS_FUNC] // op->func + blr x4 // op->func(ip, parent_ip, op, regs) + +#else + ldr_l x2, function_trace_op // op SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL) - bl ftrace_stub + bl ftrace_stub // func(ip, parent_ip, op, regs) +#endif /* * At the callsite x0-x8 and x19-x30 were live. Any C code will have preserved @@ -85,8 +123,15 @@ SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL) ldp x6, x7, [sp, #FREGS_X6] ldr x8, [sp, #FREGS_X8] - /* Restore the callsite's FP, LR, PC */ + /* Restore the callsite's FP */ ldr x29, [sp, #FREGS_FP] + +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS + ldr x17, [sp, #FREGS_DIRECT_TRAMP] + cbnz x17, ftrace_caller_direct_late +#endif + + /* Restore the callsite's LR and PC */ ldr x30, [sp, #FREGS_LR] ldr x9, [sp, #FREGS_PC] @@ -94,8 +139,45 @@ SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL) add sp, sp, #FREGS_SIZE + 32 ret x9 + +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS +SYM_INNER_LABEL(ftrace_caller_direct_late, SYM_L_LOCAL) + /* + * Head to a direct trampoline in x17 after having run other tracers. + * The ftrace_regs are live, and x0-x8 and FP have been restored. The + * LR, PC, and SP have not been restored. + */ + + /* + * Restore the callsite's LR and PC matching the trampoline calling + * convention. + */ + ldr x9, [sp, #FREGS_LR] + ldr x30, [sp, #FREGS_PC] + + /* Restore the callsite's SP */ + add sp, sp, #FREGS_SIZE + 32 + +SYM_INNER_LABEL(ftrace_caller_direct, SYM_L_LOCAL) + /* + * Head to a direct trampoline in x17. + * + * We use `BR X17` as this can safely land on a `BTI C` or `PACIASP` in + * the trampoline, and will not unbalance any return stack. + */ + br x17 +#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */ SYM_CODE_END(ftrace_caller) +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS +SYM_CODE_START(ftrace_stub_direct_tramp) + bti c + mov x10, x30 + mov x30, x9 + ret x10 +SYM_CODE_END(ftrace_stub_direct_tramp) +#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */ + #else /* CONFIG_DYNAMIC_FTRACE_WITH_ARGS */ /* @@ -247,23 +329,28 @@ SYM_FUNC_END(ftrace_stub_graph) * @fp is checked against the value passed by ftrace_graph_caller(). */ SYM_CODE_START(return_to_handler) - /* save return value regs */ - sub sp, sp, #64 - stp x0, x1, [sp] - stp x2, x3, [sp, #16] - stp x4, x5, [sp, #32] - stp x6, x7, [sp, #48] - - mov x0, x29 // parent's fp - bl ftrace_return_to_handler// addr = ftrace_return_to_hander(fp); - mov x30, x0 // restore the original return address - - /* restore return value regs */ - ldp x0, x1, [sp] - ldp x2, x3, [sp, #16] - ldp x4, x5, [sp, #32] - ldp x6, x7, [sp, #48] - add sp, sp, #64 + /* Make room for ftrace_regs */ + sub sp, sp, #FREGS_SIZE + + /* Save return value regs */ + stp x0, x1, [sp, #FREGS_X0] + stp x2, x3, [sp, #FREGS_X2] + stp x4, x5, [sp, #FREGS_X4] + stp x6, x7, [sp, #FREGS_X6] + + /* Save the callsite's FP */ + str x29, [sp, #FREGS_FP] + + mov x0, sp + bl ftrace_return_to_handler // addr = ftrace_return_to_hander(fregs); + mov x30, x0 // restore the original return address + + /* Restore return value regs */ + ldp x0, x1, [sp, #FREGS_X0] + ldp x2, x3, [sp, #FREGS_X2] + ldp x4, x5, [sp, #FREGS_X4] + ldp x6, x7, [sp, #FREGS_X6] + add sp, sp, #FREGS_SIZE ret SYM_CODE_END(return_to_handler) |