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/* SPDX-License-Identifier: GPL-2.0 */
/* Copyright (C) 2017 Andes Technology Corporation */
#include <linux/init.h>
#include <linux/linkage.h>
#include <linux/export.h>
#include <asm/asm.h>
#include <asm/csr.h>
#include <asm/unistd.h>
#include <asm/thread_info.h>
#include <asm/asm-offsets.h>
#include <asm/ftrace.h>
.text
#define ABI_SIZE_ON_STACK 80
#define ABI_A0 0
#define ABI_A1 8
#define ABI_A2 16
#define ABI_A3 24
#define ABI_A4 32
#define ABI_A5 40
#define ABI_A6 48
#define ABI_A7 56
#define ABI_T0 64
#define ABI_RA 72
.macro SAVE_ABI
addi sp, sp, -ABI_SIZE_ON_STACK
REG_S a0, ABI_A0(sp)
REG_S a1, ABI_A1(sp)
REG_S a2, ABI_A2(sp)
REG_S a3, ABI_A3(sp)
REG_S a4, ABI_A4(sp)
REG_S a5, ABI_A5(sp)
REG_S a6, ABI_A6(sp)
REG_S a7, ABI_A7(sp)
REG_S t0, ABI_T0(sp)
REG_S ra, ABI_RA(sp)
.endm
.macro RESTORE_ABI
REG_L a0, ABI_A0(sp)
REG_L a1, ABI_A1(sp)
REG_L a2, ABI_A2(sp)
REG_L a3, ABI_A3(sp)
REG_L a4, ABI_A4(sp)
REG_L a5, ABI_A5(sp)
REG_L a6, ABI_A6(sp)
REG_L a7, ABI_A7(sp)
REG_L t0, ABI_T0(sp)
REG_L ra, ABI_RA(sp)
addi sp, sp, ABI_SIZE_ON_STACK
.endm
/**
* SAVE_ABI_REGS - save regs against the ftrace_regs struct
*
* After the stack is established,
*
* 0(sp) stores the PC of the traced function which can be accessed
* by &(fregs)->epc in tracing function.
*
* 8(sp) stores the function return address (i.e. parent IP) that
* can be accessed by &(fregs)->ra in tracing function.
*
* The other regs are saved at the respective localtion and accessed
* by the respective ftrace_regs member.
*
* Here is the layout of stack for your reference.
*
* PT_SIZE_ON_STACK -> +++++++++
* + ..... +
* + a0-a7 + --++++-> ftrace_caller saved
* + t1 + --++++-> direct tramp address
* + s0 + --+ // frame pointer
* + sp + +
* + ra + --+ // parent IP
* sp -> + epc + --+ // PC
* +++++++++
**/
.macro SAVE_ABI_REGS
addi sp, sp, -FREGS_SIZE_ON_STACK
REG_S t0, FREGS_EPC(sp)
REG_S x1, FREGS_RA(sp)
#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
REG_S x8, FREGS_S0(sp)
#endif
REG_S x6, FREGS_T1(sp)
#ifdef CONFIG_CC_IS_CLANG
REG_S x7, FREGS_T2(sp)
REG_S x28, FREGS_T3(sp)
REG_S x29, FREGS_T4(sp)
REG_S x30, FREGS_T5(sp)
REG_S x31, FREGS_T6(sp)
#endif
// save the arguments
REG_S x10, FREGS_A0(sp)
REG_S x11, FREGS_A1(sp)
REG_S x12, FREGS_A2(sp)
REG_S x13, FREGS_A3(sp)
REG_S x14, FREGS_A4(sp)
REG_S x15, FREGS_A5(sp)
REG_S x16, FREGS_A6(sp)
REG_S x17, FREGS_A7(sp)
mv a0, sp
addi a0, a0, FREGS_SIZE_ON_STACK
REG_S a0, FREGS_SP(sp) // Put original SP on stack
.endm
.macro RESTORE_ABI_REGS
REG_L t0, FREGS_EPC(sp)
REG_L x1, FREGS_RA(sp)
#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
REG_L x8, FREGS_S0(sp)
#endif
REG_L x6, FREGS_T1(sp)
#ifdef CONFIG_CC_IS_CLANG
REG_L x7, FREGS_T2(sp)
REG_L x28, FREGS_T3(sp)
REG_L x29, FREGS_T4(sp)
REG_L x30, FREGS_T5(sp)
REG_L x31, FREGS_T6(sp)
#endif
// restore the arguments
REG_L x10, FREGS_A0(sp)
REG_L x11, FREGS_A1(sp)
REG_L x12, FREGS_A2(sp)
REG_L x13, FREGS_A3(sp)
REG_L x14, FREGS_A4(sp)
REG_L x15, FREGS_A5(sp)
REG_L x16, FREGS_A6(sp)
REG_L x17, FREGS_A7(sp)
addi sp, sp, FREGS_SIZE_ON_STACK
.endm
.macro PREPARE_ARGS
addi a0, t0, -MCOUNT_JALR_SIZE // ip (callsite's jalr insn)
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS
mv a1, ra // parent_ip
REG_L a2, -16(t0) // op
REG_L ra, FTRACE_OPS_FUNC(a2) // op->func
#else
la a1, function_trace_op
REG_L a2, 0(a1) // op
mv a1, ra // parent_ip
#endif
mv a3, sp // regs
.endm
SYM_FUNC_START(ftrace_caller)
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS
/*
* When CALL_OPS is enabled (2 or 4) nops [8B] are placed before the
* function entry, these are later overwritten with the pointer to the
* associated struct ftrace_ops.
*
* -8: &ftrace_ops of the associated tracer function.
*<ftrace enable>:
* 0: auipc t0/ra, 0x?
* 4: jalr t0/ra, ?(t0/ra)
*
* -8: &ftrace_nop_ops
*<ftrace disable>:
* 0: nop
* 4: nop
*
* t0 is set to ip+8 after the jalr is executed at the callsite,
* so we find the associated op at t0-16.
*/
REG_L t1, -16(t0) // op Should be SZ_REG instead of 16
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
/*
* If the op has a direct call, handle it immediately without
* saving/restoring registers.
*/
REG_L t1, FTRACE_OPS_DIRECT_CALL(t1)
bnez t1, ftrace_caller_direct
#endif
#endif
SAVE_ABI_REGS
PREPARE_ARGS
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS
jalr ra
#else
SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL)
REG_L ra, ftrace_call_dest
jalr ra, 0(ra)
#endif
RESTORE_ABI_REGS
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
bnez t1, ftrace_caller_direct
#endif
jr t0
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
SYM_INNER_LABEL(ftrace_caller_direct, SYM_L_LOCAL)
jr t1
#endif
SYM_FUNC_END(ftrace_caller)
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
SYM_CODE_START(ftrace_stub_direct_tramp)
jr t0
SYM_CODE_END(ftrace_stub_direct_tramp)
#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
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