diff options
Diffstat (limited to 'arch/x86/kernel/ftrace_64.S')
| -rw-r--r-- | arch/x86/kernel/ftrace_64.S | 143 |
1 files changed, 110 insertions, 33 deletions
diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S index 11ac028e30e4..a132608265f6 100644 --- a/arch/x86/kernel/ftrace_64.S +++ b/arch/x86/kernel/ftrace_64.S @@ -3,10 +3,12 @@ * Copyright (C) 2014 Steven Rostedt, Red Hat Inc */ +#include <linux/export.h> +#include <linux/cfi_types.h> #include <linux/linkage.h> +#include <asm/asm-offsets.h> #include <asm/ptrace.h> #include <asm/ftrace.h> -#include <asm/export.h> #include <asm/nospec-branch.h> #include <asm/unwind_hints.h> #include <asm/frame.h> @@ -129,22 +131,40 @@ .endm +SYM_TYPED_FUNC_START(ftrace_stub) + CALL_DEPTH_ACCOUNT + RET +SYM_FUNC_END(ftrace_stub) + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +SYM_TYPED_FUNC_START(ftrace_stub_graph) + CALL_DEPTH_ACCOUNT + RET +SYM_FUNC_END(ftrace_stub_graph) +#endif + #ifdef CONFIG_DYNAMIC_FTRACE SYM_FUNC_START(__fentry__) + ANNOTATE_NOENDBR + CALL_DEPTH_ACCOUNT RET SYM_FUNC_END(__fentry__) EXPORT_SYMBOL(__fentry__) SYM_FUNC_START(ftrace_caller) + ANNOTATE_NOENDBR /* save_mcount_regs fills in first two parameters */ save_mcount_regs + CALL_DEPTH_ACCOUNT + /* Stack - skipping return address of ftrace_caller */ leaq MCOUNT_REG_SIZE+8(%rsp), %rcx movq %rcx, RSP(%rsp) SYM_INNER_LABEL(ftrace_caller_op_ptr, SYM_L_GLOBAL) + ANNOTATE_NOENDBR /* Load the ftrace_ops into the 3rd parameter */ movq function_trace_op(%rip), %rdx @@ -154,7 +174,11 @@ SYM_INNER_LABEL(ftrace_caller_op_ptr, SYM_L_GLOBAL) /* Only ops with REGS flag set should have CS register set */ movq $0, CS(%rsp) + /* Account for the function call below */ + CALL_DEPTH_ACCOUNT + SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL) + ANNOTATE_NOENDBR call ftrace_stub /* Handlers can change the RIP */ @@ -169,21 +193,13 @@ SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL) * layout here. */ SYM_INNER_LABEL(ftrace_caller_end, SYM_L_GLOBAL) - - jmp ftrace_epilogue -SYM_FUNC_END(ftrace_caller); - -SYM_FUNC_START(ftrace_epilogue) -/* - * This is weak to keep gas from relaxing the jumps. - * It is also used to copy the RET for trampolines. - */ -SYM_INNER_LABEL_ALIGN(ftrace_stub, SYM_L_WEAK) - UNWIND_HINT_FUNC + ANNOTATE_NOENDBR RET -SYM_FUNC_END(ftrace_epilogue) +SYM_FUNC_END(ftrace_caller); +STACK_FRAME_NON_STANDARD_FP(ftrace_caller) SYM_FUNC_START(ftrace_regs_caller) + ANNOTATE_NOENDBR /* Save the current flags before any operations that can change them */ pushfq @@ -191,7 +207,10 @@ SYM_FUNC_START(ftrace_regs_caller) save_mcount_regs 8 /* save_mcount_regs fills in first two parameters */ + CALL_DEPTH_ACCOUNT + SYM_INNER_LABEL(ftrace_regs_caller_op_ptr, SYM_L_GLOBAL) + ANNOTATE_NOENDBR /* Load the ftrace_ops into the 3rd parameter */ movq function_trace_op(%rip), %rdx @@ -220,7 +239,11 @@ SYM_INNER_LABEL(ftrace_regs_caller_op_ptr, SYM_L_GLOBAL) /* regs go into 4th parameter */ leaq (%rsp), %rcx + /* Account for the function call below */ + CALL_DEPTH_ACCOUNT + SYM_INNER_LABEL(ftrace_regs_call, SYM_L_GLOBAL) + ANNOTATE_NOENDBR call ftrace_stub /* Copy flags back to SS, to restore them */ @@ -248,6 +271,7 @@ SYM_INNER_LABEL(ftrace_regs_call, SYM_L_GLOBAL) */ testq %rax, %rax SYM_INNER_LABEL(ftrace_regs_caller_jmp, SYM_L_GLOBAL) + ANNOTATE_NOENDBR jnz 1f restore_mcount_regs @@ -255,16 +279,24 @@ SYM_INNER_LABEL(ftrace_regs_caller_jmp, SYM_L_GLOBAL) popfq /* - * As this jmp to ftrace_epilogue can be a short jump - * it must not be copied into the trampoline. - * The trampoline will add the code to jump - * to the return. + * The trampoline will add the return. */ SYM_INNER_LABEL(ftrace_regs_caller_end, SYM_L_GLOBAL) - jmp ftrace_epilogue + ANNOTATE_NOENDBR + RET + +1: + testb $1, %al + jz 2f + andq $0xfffffffffffffffe, %rax + movq %rax, MCOUNT_REG_SIZE+8(%rsp) + restore_mcount_regs + /* Restore flags */ + popfq + RET /* Swap the flags with orig_rax */ -1: movq MCOUNT_REG_SIZE(%rsp), %rdi +2: movq MCOUNT_REG_SIZE(%rsp), %rdi movq %rdi, MCOUNT_REG_SIZE-8(%rsp) movq %rax, MCOUNT_REG_SIZE(%rsp) @@ -272,18 +304,38 @@ SYM_INNER_LABEL(ftrace_regs_caller_end, SYM_L_GLOBAL) /* Restore flags */ popfq UNWIND_HINT_FUNC - jmp ftrace_epilogue + + /* + * The above left an extra return value on the stack; effectively + * doing a tail-call without using a register. This PUSH;RET + * pattern unbalances the RSB, inject a pointless CALL to rebalance. + */ + ANNOTATE_INTRA_FUNCTION_CALL + CALL .Ldo_rebalance + int3 +.Ldo_rebalance: + add $8, %rsp + ALTERNATIVE __stringify(RET), \ + __stringify(ANNOTATE_UNRET_SAFE; ret; int3), \ + X86_FEATURE_CALL_DEPTH SYM_FUNC_END(ftrace_regs_caller) +STACK_FRAME_NON_STANDARD_FP(ftrace_regs_caller) +SYM_FUNC_START(ftrace_stub_direct_tramp) + ANNOTATE_NOENDBR + CALL_DEPTH_ACCOUNT + RET +SYM_FUNC_END(ftrace_stub_direct_tramp) #else /* ! CONFIG_DYNAMIC_FTRACE */ SYM_FUNC_START(__fentry__) + ANNOTATE_NOENDBR + CALL_DEPTH_ACCOUNT + cmpq $ftrace_stub, ftrace_trace_function jnz trace - -SYM_INNER_LABEL(ftrace_stub, SYM_L_GLOBAL) RET trace: @@ -303,23 +355,48 @@ trace: jmp ftrace_stub SYM_FUNC_END(__fentry__) EXPORT_SYMBOL(__fentry__) +STACK_FRAME_NON_STANDARD_FP(__fentry__) + #endif /* CONFIG_DYNAMIC_FTRACE */ #ifdef CONFIG_FUNCTION_GRAPH_TRACER -SYM_FUNC_START(return_to_handler) - subq $24, %rsp +SYM_CODE_START(return_to_handler) + UNWIND_HINT_UNDEFINED + ANNOTATE_NOENDBR - /* Save the return values */ - movq %rax, (%rsp) - movq %rdx, 8(%rsp) - movq %rbp, %rdi + /* Restore return_to_handler value that got eaten by previous ret instruction. */ + subq $8, %rsp + UNWIND_HINT_FUNC + + /* Save ftrace_regs for function exit context */ + subq $(FRAME_SIZE), %rsp + + movq %rax, RAX(%rsp) + movq %rdx, RDX(%rsp) + movq %rbp, RBP(%rsp) + movq %rsp, RSP(%rsp) + movq %rsp, %rdi call ftrace_return_to_handler movq %rax, %rdi - movq 8(%rsp), %rdx - movq (%rsp), %rax - addq $24, %rsp - JMP_NOSPEC rdi -SYM_FUNC_END(return_to_handler) + movq RDX(%rsp), %rdx + movq RAX(%rsp), %rax + + addq $(FRAME_SIZE) + 8, %rsp + + /* + * Jump back to the old return address. This cannot be JMP_NOSPEC rdi + * since IBT would demand that contain ENDBR, which simply isn't so for + * return addresses. Use a retpoline here to keep the RSB balanced. + */ + ANNOTATE_INTRA_FUNCTION_CALL + call .Ldo_rop + int3 +.Ldo_rop: + mov %rdi, (%rsp) + ALTERNATIVE __stringify(RET), \ + __stringify(ANNOTATE_UNRET_SAFE; ret; int3), \ + X86_FEATURE_CALL_DEPTH +SYM_CODE_END(return_to_handler) #endif |