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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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afc76b8b80
This patch changes the current detour mechanism of dynamic ftrace which has been discussed during LPC 2020 RISCV-MC [1]. Before the patch, we used mcount for detour: <funca>: addi sp,sp,-16 sd ra,8(sp) sd s0,0(sp) addi s0,sp,16 mv a5,ra mv a0,a5 auipc ra,0x0 -> nop jalr -296(ra) <_mcount@plt> ->nop ... After the patch, we use nop call site area for detour: <funca>: nop -> REG_S ra, -SZREG(sp) nop -> auipc ra, 0x? nop -> jalr ?(ra) nop -> REG_L ra, -SZREG(sp) ... The mcount mechanism is mixed with gcc function prologue which is not very clear. The patchable function entry just put 16 bytes nop before the front of the function prologue which could be filled with a separated detour mechanism. [1] https://www.linuxplumbersconf.org/event/7/contributions/807/ Signed-off-by: Guo Ren <guoren@linux.alibaba.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
201 lines
4 KiB
ArmAsm
201 lines
4 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
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/* Copyright (C) 2017 Andes Technology Corporation */
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#include <linux/init.h>
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#include <linux/linkage.h>
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#include <asm/asm.h>
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#include <asm/csr.h>
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#include <asm/unistd.h>
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#include <asm/thread_info.h>
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#include <asm/asm-offsets.h>
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#include <asm-generic/export.h>
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#include <asm/ftrace.h>
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.text
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#define FENTRY_RA_OFFSET 12
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#define ABI_SIZE_ON_STACK 72
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#define ABI_A0 0
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#define ABI_A1 8
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#define ABI_A2 16
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#define ABI_A3 24
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#define ABI_A4 32
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#define ABI_A5 40
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#define ABI_A6 48
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#define ABI_A7 56
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#define ABI_RA 64
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.macro SAVE_ABI
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addi sp, sp, -SZREG
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addi sp, sp, -ABI_SIZE_ON_STACK
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REG_S a0, ABI_A0(sp)
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REG_S a1, ABI_A1(sp)
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REG_S a2, ABI_A2(sp)
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REG_S a3, ABI_A3(sp)
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REG_S a4, ABI_A4(sp)
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REG_S a5, ABI_A5(sp)
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REG_S a6, ABI_A6(sp)
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REG_S a7, ABI_A7(sp)
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REG_S ra, ABI_RA(sp)
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.endm
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.macro RESTORE_ABI
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REG_L a0, ABI_A0(sp)
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REG_L a1, ABI_A1(sp)
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REG_L a2, ABI_A2(sp)
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REG_L a3, ABI_A3(sp)
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REG_L a4, ABI_A4(sp)
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REG_L a5, ABI_A5(sp)
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REG_L a6, ABI_A6(sp)
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REG_L a7, ABI_A7(sp)
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REG_L ra, ABI_RA(sp)
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addi sp, sp, ABI_SIZE_ON_STACK
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addi sp, sp, SZREG
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.endm
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#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
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.macro SAVE_ALL
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addi sp, sp, -SZREG
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addi sp, sp, -PT_SIZE_ON_STACK
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REG_S x1, PT_EPC(sp)
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addi sp, sp, PT_SIZE_ON_STACK
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REG_L x1, (sp)
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addi sp, sp, -PT_SIZE_ON_STACK
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REG_S x1, PT_RA(sp)
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REG_L x1, PT_EPC(sp)
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REG_S x2, PT_SP(sp)
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REG_S x3, PT_GP(sp)
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REG_S x4, PT_TP(sp)
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REG_S x5, PT_T0(sp)
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REG_S x6, PT_T1(sp)
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REG_S x7, PT_T2(sp)
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REG_S x8, PT_S0(sp)
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REG_S x9, PT_S1(sp)
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REG_S x10, PT_A0(sp)
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REG_S x11, PT_A1(sp)
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REG_S x12, PT_A2(sp)
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REG_S x13, PT_A3(sp)
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REG_S x14, PT_A4(sp)
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REG_S x15, PT_A5(sp)
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REG_S x16, PT_A6(sp)
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REG_S x17, PT_A7(sp)
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REG_S x18, PT_S2(sp)
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REG_S x19, PT_S3(sp)
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REG_S x20, PT_S4(sp)
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REG_S x21, PT_S5(sp)
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REG_S x22, PT_S6(sp)
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REG_S x23, PT_S7(sp)
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REG_S x24, PT_S8(sp)
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REG_S x25, PT_S9(sp)
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REG_S x26, PT_S10(sp)
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REG_S x27, PT_S11(sp)
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REG_S x28, PT_T3(sp)
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REG_S x29, PT_T4(sp)
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REG_S x30, PT_T5(sp)
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REG_S x31, PT_T6(sp)
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.endm
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.macro RESTORE_ALL
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REG_L x1, PT_RA(sp)
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addi sp, sp, PT_SIZE_ON_STACK
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REG_S x1, (sp)
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addi sp, sp, -PT_SIZE_ON_STACK
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REG_L x1, PT_EPC(sp)
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REG_L x2, PT_SP(sp)
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REG_L x3, PT_GP(sp)
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REG_L x4, PT_TP(sp)
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REG_L x5, PT_T0(sp)
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REG_L x6, PT_T1(sp)
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REG_L x7, PT_T2(sp)
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REG_L x8, PT_S0(sp)
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REG_L x9, PT_S1(sp)
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REG_L x10, PT_A0(sp)
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REG_L x11, PT_A1(sp)
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REG_L x12, PT_A2(sp)
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REG_L x13, PT_A3(sp)
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REG_L x14, PT_A4(sp)
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REG_L x15, PT_A5(sp)
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REG_L x16, PT_A6(sp)
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REG_L x17, PT_A7(sp)
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REG_L x18, PT_S2(sp)
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REG_L x19, PT_S3(sp)
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REG_L x20, PT_S4(sp)
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REG_L x21, PT_S5(sp)
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REG_L x22, PT_S6(sp)
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REG_L x23, PT_S7(sp)
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REG_L x24, PT_S8(sp)
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REG_L x25, PT_S9(sp)
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REG_L x26, PT_S10(sp)
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REG_L x27, PT_S11(sp)
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REG_L x28, PT_T3(sp)
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REG_L x29, PT_T4(sp)
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REG_L x30, PT_T5(sp)
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REG_L x31, PT_T6(sp)
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addi sp, sp, PT_SIZE_ON_STACK
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addi sp, sp, SZREG
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.endm
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#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
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ENTRY(ftrace_caller)
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SAVE_ABI
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addi a0, ra, -FENTRY_RA_OFFSET
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la a1, function_trace_op
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REG_L a2, 0(a1)
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REG_L a1, ABI_SIZE_ON_STACK(sp)
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mv a3, sp
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ftrace_call:
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.global ftrace_call
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call ftrace_stub
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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addi a0, sp, ABI_SIZE_ON_STACK
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REG_L a1, ABI_RA(sp)
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addi a1, a1, -FENTRY_RA_OFFSET
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#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
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mv a2, s0
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#endif
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ftrace_graph_call:
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.global ftrace_graph_call
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call ftrace_stub
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#endif
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RESTORE_ABI
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ret
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ENDPROC(ftrace_caller)
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#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
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ENTRY(ftrace_regs_caller)
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SAVE_ALL
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addi a0, ra, -FENTRY_RA_OFFSET
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la a1, function_trace_op
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REG_L a2, 0(a1)
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REG_L a1, PT_SIZE_ON_STACK(sp)
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mv a3, sp
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ftrace_regs_call:
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.global ftrace_regs_call
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call ftrace_stub
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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addi a0, sp, PT_RA
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REG_L a1, PT_EPC(sp)
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addi a1, a1, -FENTRY_RA_OFFSET
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#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
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mv a2, s0
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#endif
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ftrace_graph_regs_call:
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.global ftrace_graph_regs_call
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call ftrace_stub
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#endif
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RESTORE_ALL
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ret
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ENDPROC(ftrace_regs_caller)
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#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
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