linux kernel使用技巧

本文主要是介绍linux kernel使用技巧，对大家解决编程问题具有一定的参考价值，需要的程序猿们随着小编来一起学习吧！

技巧

• • • • 1、 在linux kernel中读写ARM寄存器示例
      • 2、 在optee中读写ARM寄存器示例
      • 3、自定义log打印函数

1、 在linux kernel中读写ARM寄存器示例

#define FUNCTION_INVARIANT(reg)						\
	static void get_##reg(struct kvm_vcpu *v,			\
			      const struct sys_reg_desc *r)		\
	{								\
		u64 val;						\
									\
		asm volatile("mrs %0, " __stringify(reg) "\n"		\
			     : "=r" (val));				\
		((struct sys_reg_desc *)r)->val = val;			\
	}

FUNCTION_INVARIANT(midr_el1)
FUNCTION_INVARIANT(ctr_el0)
FUNCTION_INVARIANT(revidr_el1)
FUNCTION_INVARIANT(id_pfr0_el1)
FUNCTION_INVARIANT(id_pfr1_el1)
FUNCTION_INVARIANT(id_dfr0_el1)
FUNCTION_INVARIANT(id_afr0_el1)
FUNCTION_INVARIANT(id_mmfr0_el1)
FUNCTION_INVARIANT(id_mmfr1_el1)
FUNCTION_INVARIANT(id_mmfr2_el1)
FUNCTION_INVARIANT(id_mmfr3_el1)
FUNCTION_INVARIANT(id_isar0_el1)
FUNCTION_INVARIANT(id_isar1_el1)
FUNCTION_INVARIANT(id_isar2_el1)
FUNCTION_INVARIANT(id_isar3_el1)
FUNCTION_INVARIANT(id_isar4_el1)
FUNCTION_INVARIANT(id_isar5_el1)
FUNCTION_INVARIANT(clidr_el1)
FUNCTION_INVARIANT(aidr_el1)

2、 在optee中读写ARM寄存器示例

#define DEFINE_REG_READ_FUNC_(reg, type, asmreg)	\
static inline type read_##reg(void)			\
{							\
	type val;					\
							\
	asm volatile("mrs %0, " #asmreg : "=r" (val));	\
	return val;					\
}

#define DEFINE_REG_WRITE_FUNC_(reg, type, asmreg)		\
static inline void write_##reg(type val)			\
{								\
	asm volatile("msr " #asmreg ", %0" : : "r" (val));	\
}

#define DEFINE_U32_REG_READ_FUNC(reg) \
		DEFINE_REG_READ_FUNC_(reg, uint32_t, reg)

#define DEFINE_U32_REG_WRITE_FUNC(reg) \
		DEFINE_REG_WRITE_FUNC_(reg, uint32_t, reg)

#define DEFINE_U32_REG_READWRITE_FUNCS(reg)	\
		DEFINE_U32_REG_READ_FUNC(reg)	\
		DEFINE_U32_REG_WRITE_FUNC(reg)

#define DEFINE_U64_REG_READ_FUNC(reg) \
		DEFINE_REG_READ_FUNC_(reg, uint64_t, reg)

#define DEFINE_U64_REG_WRITE_FUNC(reg) \
		DEFINE_REG_WRITE_FUNC_(reg, uint64_t, reg)

#define DEFINE_U64_REG_READWRITE_FUNCS(reg)	\
		DEFINE_U64_REG_READ_FUNC(reg)	\
		DEFINE_U64_REG_WRITE_FUNC(reg)

DEFINE_U32_REG_READWRITE_FUNCS(cpacr_el1)
DEFINE_U32_REG_READWRITE_FUNCS(daif)
DEFINE_U32_REG_READWRITE_FUNCS(fpcr)
DEFINE_U32_REG_READWRITE_FUNCS(fpsr)

DEFINE_U32_REG_READ_FUNC(contextidr_el1)
DEFINE_U32_REG_READ_FUNC(sctlr_el1)

/* ARM Generic timer functions */
DEFINE_REG_READ_FUNC_(cntfrq, uint32_t, cntfrq_el0)
DEFINE_REG_READ_FUNC_(cntpct, uint64_t, cntpct_el0)
DEFINE_REG_READ_FUNC_(cntkctl, uint32_t, cntkctl_el1)
DEFINE_REG_WRITE_FUNC_(cntkctl, uint32_t, cntkctl_el1)

DEFINE_U64_REG_READWRITE_FUNCS(ttbr0_el1)
DEFINE_U64_REG_READWRITE_FUNCS(ttbr1_el1)
DEFINE_U64_REG_READWRITE_FUNCS(tcr_el1)

DEFINE_U64_REG_READ_FUNC(esr_el1)
DEFINE_U64_REG_READ_FUNC(far_el1)
DEFINE_U64_REG_READ_FUNC(mpidr_el1)
DEFINE_U64_REG_READ_FUNC(midr_el1)
/* Alias for reading this register to avoid ifdefs in code */
#define read_midr() read_midr_el1()
DEFINE_U64_REG_READ_FUNC(par_el1)

DEFINE_U64_REG_WRITE_FUNC(mair_el1)

/* Register read/write functions for GICC registers by using system interface */
DEFINE_REG_READ_FUNC_(icc_ctlr, uint32_t, S3_0_C12_C12_4)
DEFINE_REG_WRITE_FUNC_(icc_ctlr, uint32_t, S3_0_C12_C12_4)
DEFINE_REG_WRITE_FUNC_(icc_pmr, uint32_t, S3_0_C4_C6_0)
DEFINE_REG_READ_FUNC_(icc_iar0, uint32_t, S3_0_c12_c8_0)
DEFINE_REG_READ_FUNC_(icc_iar1, uint32_t, S3_0_c12_c12_0)
DEFINE_REG_WRITE_FUNC_(icc_eoir0, uint32_t, S3_0_c12_c8_1)
DEFINE_REG_WRITE_FUNC_(icc_eoir1, uint32_t, S3_0_c12_c12_1)

3、自定义log打印函数

#define XXXX_PRINTK(fmt, ...)           ALOGI(fmt, ##__VA_ARGS__)
#define XXXX_ENTER()           XXXX_PRINTK("%d : %s :enter",__LINE__, __func__)
#define XXXX_EXIT()           XXXX_PRINTK("%d : %s :exit",__LINE__, __func__)

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