arch/loongarch/kernel/mcount_dyn.S

Source file repositories/reference/linux-study-clean/arch/loongarch/kernel/mcount_dyn.S

File Facts

System
Linux kernel
Corpus path
arch/loongarch/kernel/mcount_dyn.S
Extension
.S
Size
4315 bytes
Lines
173
Domain
Architecture Layer
Bucket
arch/loongarch
Inferred role
Architecture Layer: arch/loongarch
Status
atlas-only

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

#include <asm/ftrace.h>
#include <asm/regdef.h>
#include <asm/stackframe.h>

	.text
/*
 * Due to -fpatchable-function-entry=2: the compiler inserted 2 NOPs before the
 * regular C function prologue. When PC arrived here, the last 2 instructions
 * are as follows:
 * 	move		t0, ra
 * 	bl		callsite (for modules, callsite is a tramplione)
 *
 * modules trampoline is as follows:
 * 	lu12i.w		t1, callsite[31:12]
 * 	lu32i.d		t1, callsite[51:32]
 * 	lu52i.d		t1, t1, callsite[63:52]
 * 	jirl		zero, t1, callsite[11:0] >> 2
 *
 * See arch/loongarch/kernel/ftrace_dyn.c for details. Here, pay attention to
 * that the T series regs are available and safe because each C functions
 * follows the LoongArch's psABI as well.
 */

	.macro  ftrace_regs_entry allregs=0
	PTR_ADDI	sp, sp, -PT_SIZE
	PTR_S		t0, sp, PT_R1  /* Save parent ra at PT_R1(RA) */
	PTR_S		a0, sp, PT_R4
	PTR_S		a1, sp, PT_R5
	PTR_S		a2, sp, PT_R6
	PTR_S		a3, sp, PT_R7
	PTR_S		a4, sp, PT_R8
	PTR_S		a5, sp, PT_R9
	PTR_S		a6, sp, PT_R10
	PTR_S		a7, sp, PT_R11
	PTR_S		fp, sp, PT_R22
	.if \allregs
	PTR_S		tp, sp, PT_R2
	PTR_S		t0, sp, PT_R12
	PTR_S		t2, sp, PT_R14
	PTR_S		t3, sp, PT_R15
	PTR_S		t4, sp, PT_R16
	PTR_S		t5, sp, PT_R17
	PTR_S		t6, sp, PT_R18
	PTR_S		t7, sp, PT_R19
	PTR_S		t8, sp, PT_R20
	PTR_S		u0, sp, PT_R21
	PTR_S		s0, sp, PT_R23
	PTR_S		s1, sp, PT_R24
	PTR_S		s2, sp, PT_R25
	PTR_S		s3, sp, PT_R26
	PTR_S		s4, sp, PT_R27
	PTR_S		s5, sp, PT_R28
	PTR_S		s6, sp, PT_R29
	PTR_S		s7, sp, PT_R30
	PTR_S		s8, sp, PT_R31
	/* Clear it for later use as a flag sometimes. */
	PTR_S		zero, sp, PT_R0
	.endif
	PTR_S		ra, sp, PT_ERA /* Save trace function ra at PT_ERA */
	move		t1, zero
	PTR_S		t1, sp, PT_R13
	PTR_ADDI	t8, sp, PT_SIZE
	PTR_S		t8, sp, PT_R3
	.endm

SYM_FUNC_START(ftrace_stub)
	jr		ra
SYM_FUNC_END(ftrace_stub)

SYM_CODE_START(ftrace_common)

Annotation

Implementation Notes