文章目录
1、save/restore函数的定义
（1）、el1_sysregs_context_save //保存系统寄存器
/* -----------------------------------------------------
* The following function strictly follows the AArch64
* PCS to use x9-x17 (temporary caller-saved registers)
* to save EL1 system register context. It assumes that
* 'x0' is pointing to a 'el1_sys_regs' structure where
* the register context will be saved.
* -----------------------------------------------------
*/
func el1_sysregs_context_save
mrs x9, spsr_el1
mrs x10, elr_el1
stp x9, x10, [x0, #CTX_SPSR_EL1]
mrs x11, spsr_abt
mrs x12, spsr_und
stp x11, x12, [x0, #CTX_SPSR_ABT]
mrs x13, spsr_irq
mrs x14, spsr_fiq
stp x13, x14, [x0, #CTX_SPSR_IRQ]
mrs x15, sctlr_el1
mrs x16, actlr_el1
stp x15, x16, [x0, #CTX_SCTLR_EL1]
mrs x17, cpacr_el1
mrs x9, csselr_el1
stp x17, x9, [x0, #CTX_CPACR_EL1]
mrs x10, sp_el1
mrs x11, esr_el1
stp x10, x11, [x0, #CTX_SP_EL1]
mrs x12, ttbr0_el1
mrs x13, ttbr1_el1
stp x12, x13, [x0, #CTX_TTBR0_EL1]
mrs x14, mair_el1
mrs x15, amair_el1
stp x14, x15, [x0, #CTX_MAIR_EL1]
mrs x16, tcr_el1
mrs x17, tpidr_el1
stp x16, x17, [x0, #CTX_TCR_EL1]
mrs x9, tpidr_el0
mrs x10, tpidrro_el0
stp x9, x10, [x0, #CTX_TPIDR_EL0]
#if !STPU
mrs x11, dacr32_el2
mrs x12, ifsr32_el2
stp x11, x12, [x0, #CTX_DACR32_EL2]
#endif
mrs x13, par_el1
mrs x14, far_el1
stp x13, x14, [x0, #CTX_PAR_EL1]
mrs x15, afsr0_el1
mrs x16, afsr1_el1
stp x15, x16, [x0, #CTX_AFSR0_EL1]
mrs x17, contextidr_el1
mrs x9, vbar_el1
stp x17, x9, [x0, #CTX_CONTEXTIDR_EL1]
/* Save NS timer registers if the build has instructed so */
#if NS_TIMER_SWITCH
mrs x10, cntp_ctl_el0
mrs x11, cntp_cval_el0
stp x10, x11, [x0, #CTX_CNTP_CTL_EL0]
mrs x12, cntv_ctl_el0
mrs x13, cntv_cval_el0
stp x12, x13, [x0, #CTX_CNTV_CTL_EL0]
mrs x14, cntkctl_el1
str x14, [x0, #CTX_CNTKCTL_EL1]
#endif
#if !STPU
mrs x15, fpexc32_el2
str x15, [x0, #CTX_FP_FPEXC32_EL2]
#endif
ret
endfunc el1_sysregs_context_save
（2）、el1_sysregs_context_restore //恢复系统寄存器
/* -----------------------------------------------------
* The following function strictly follows the AArch64
* PCS to use x9-x17 (temporary caller-saved registers)
* to restore EL1 system register context. It assumes
* that 'x0' is pointing to a 'el1_sys_regs' structure
* from where the register context will be restored
* -----------------------------------------------------
*/
func el1_sysregs_context_restore
ldp x9, x10, [x0, #CTX_SPSR_EL1]
msr spsr_el1, x9
msr elr_el1, x10
ldp x11, x12, [x0, #CTX_SPSR_ABT]
msr spsr_abt, x11
msr spsr_und, x12
ldp x13, x14, [x0, #CTX_SPSR_IRQ]
msr spsr_irq, x13
msr spsr_fiq, x14
ldp x15, x16, [x0, #CTX_SCTLR_EL1]
msr sctlr_el1, x15
msr actlr_el1, x16
ldp x17, x9, [x0, #CTX_CPACR_EL1]
msr cpacr_el1, x17
msr csselr_el1, x9
ldp x10, x11, [x0, #CTX_SP_EL1]
msr sp_el1, x10
msr esr_el1, x11
ldp x12, x13, [x0, #CTX_TTBR0_EL1]
msr ttbr0_el1, x12
msr ttbr1_el1, x13
ldp x14, x15, [x0, #CTX_MAIR_EL1]
msr mair_el1, x14
msr amair_el1, x15
ldp x16, x17, [x0, #CTX_TCR_EL1]
msr tcr_el1, x16
msr tpidr_el1, x17
ldp x9, x10, [x0, #CTX_TPIDR_EL0]
msr tpidr_el0, x9
msr tpidrro_el0, x10
#if !STPU
ldp x11, x12, [x0, #CTX_DACR32_EL2]
msr dacr32_el2, x11
msr ifsr32_el2, x12
#endif
ldp x13, x14, [x0, #CTX_PAR_EL1]
msr par_el1, x13
msr far_el1, x14
ldp x15, x16, [x0, #CTX_AFSR0_EL1]
msr afsr0_el1, x15
msr afsr1_el1, x16
ldp x17, x9, [x0, #CTX_CONTEXTIDR_EL1]
msr contextidr_el1, x17
msr vbar_el1, x9
/* Restore NS timer registers if the build has instructed so */
#if NS_TIMER_SWITCH
ldp x10, x11, [x0, #CTX_CNTP_CTL_EL0]
msr cntp_ctl_el0, x10
msr cntp_cval_el0, x11
ldp x12, x13, [x0, #CTX_CNTV_CTL_EL0]
msr cntv_ctl_el0, x12
msr cntv_cval_el0, x13
ldr x14, [x0, #CTX_CNTKCTL_EL1]
msr cntkctl_el1, x14
#endif
/* No explict ISB required here as ERET covers it */
ret
endfunc el1_sysregs_context_restore
（3）、restore_gp_registers_eret //保存通用寄存器
func restore_gp_registers_eret
ldp x0, x1, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X0]
ldp x2, x3, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X2]
b restore_gp_registers_callee_eret
endfunc restore_gp_registers_eret
func restore_gp_registers_callee_eret
ldp x4, x5, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X4]
ldp x6, x7, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X6]
ldp x8, x9, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X8]
ldp x10, x11, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X10]
ldp x12, x13, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X12]
ldp x14, x15, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X14]
ldp x18, x19, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X18]
ldp x20, x21, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X20]
ldp x22, x23, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X22]
ldp x24, x25, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X24]
ldp x26, x27, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X26]
ldp x28, x29, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X28]
ldp x30, x17, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR]
msr sp_el0, x17
ldp x16, x17, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X16]
eret
endfunc restore_gp_registers_callee_eret
（4）、save_gp_registers //恢复通用寄存器
/* -----------------------------------------------------
* The following functions are used to save and restore
* all the general purpose registers. Ideally we would
* only save and restore the callee saved registers when
* a world switch occurs but that type of implementation
* is more complex. So currently we will always save and
* restore these registers on entry and exit of EL3.
* These are not macros to ensure their invocation fits
* within the 32 instructions per exception vector.
* clobbers: x18
* -----------------------------------------------------
*/
func save_gp_registers
stp x0, x1, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X0]
stp x2, x3, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X2]
stp x4, x5, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X4]
stp x6, x7, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X6]
stp x8, x9, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X8]
stp x10, x11, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X10]
stp x12, x13, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X12]
stp x14, x15, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X14]
stp x16, x17, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X16]
stp x18, x19, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X18]
stp x20, x21, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X20]
stp x22, x23, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X22]
stp x24, x25, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X24]
stp x26, x27, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X26]
stp x28, x29, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X28]
mrs x18, sp_el0
str x18, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_SP_EL0]
ret
endfunc save_gp_registers
（5）、fpregs_context_save //保存浮点型寄存器
注意：搜索整个ATF代码，fpregs_context_save/fpregs_context_restore 并没有使用到
/* -----------------------------------------------------
* The following function follows the aapcs_64 strictly
* to use x9-x17 (temporary caller-saved registers
* according to AArch64 PCS) to save floating point
* register context. It assumes that 'x0' is pointing to
* a 'fp_regs' structure where the register context will
* be saved.
*
* Access to VFP registers will trap if CPTR_EL3.TFP is
* set. However currently we don't use VFP registers
* nor set traps in Trusted Firmware, and assume it's
* cleared
*
* TODO: Revisit when VFP is used in secure world
* -----------------------------------------------------
*/
#if CTX_INCLUDE_FPREGS
func fpregs_context_save
stp q0, q1, [x0, #CTX_FP_Q0]
stp q2, q3, [x0, #CTX_FP_Q2]
stp q4, q5, [x0, #CTX_FP_Q4]
stp q6, q7, [x0, #CTX_FP_Q6]
stp q8, q9, [x0, #CTX_FP_Q8]
stp q10, q11, [x0, #CTX_FP_Q10]
stp q12, q13, [x0, #CTX_FP_Q12]
stp q14, q15, [x0, #CTX_FP_Q14]
stp q16, q17, [x0, #CTX_FP_Q16]
stp q18, q19, [x0, #CTX_FP_Q18]
stp q20, q21, [x0, #CTX_FP_Q20]
stp q22, q23, [x0, #CTX_FP_Q22]
stp q24, q25, [x0, #CTX_FP_Q24]
stp q26, q27, [x0, #CTX_FP_Q26]
stp q28, q29, [x0, #CTX_FP_Q28]
stp q30, q31, [x0, #CTX_FP_Q30]
mrs x9, fpsr
str x9, [x0, #CTX_FP_FPSR]
mrs x10, fpcr
str x10, [x0, #CTX_FP_FPCR]
ret
endfunc fpregs_context_save
（6）、fpregs_context_restore //恢复浮点型寄存器
注意：搜索整个ATF代码，fpregs_context_save/fpregs_context_restore 并没有使用到
/* -----------------------------------------------------
* The following function follows the aapcs_64 strictly
* to use x9-x17 (temporary caller-saved registers
* according to AArch64 PCS) to restore floating point
* register context. It assumes that 'x0' is pointing to
* a 'fp_regs' structure from where the register context
* will be restored.
*
* Access to VFP registers will trap if CPTR_EL3.TFP is
* set. However currently we don't use VFP registers
* nor set traps in Trusted Firmware, and assume it's
* cleared
*
* TODO: Revisit when VFP is used in secure world
* -----------------------------------------------------
*/
func fpregs_context_restore
ldp q0, q1, [x0, #CTX_FP_Q0]
ldp q2, q3, [x0, #CTX_FP_Q2]
ldp q4, q5, [x0, #CTX_FP_Q4]
ldp q6, q7, [x0, #CTX_FP_Q6]
ldp q8, q9, [x0, #CTX_FP_Q8]
ldp q10, q11, [x0, #CTX_FP_Q10]
ldp q12, q13, [x0, #CTX_FP_Q12]
ldp q14, q15, [x0, #CTX_FP_Q14]
ldp q16, q17, [x0, #CTX_FP_Q16]
ldp q18, q19, [x0, #CTX_FP_Q18]
ldp q20, q21, [x0, #CTX_FP_Q20]
ldp q22, q23, [x0, #CTX_FP_Q22]
ldp q24, q25, [x0, #CTX_FP_Q24]
ldp q26, q27, [x0, #CTX_FP_Q26]
ldp q28, q29, [x0, #CTX_FP_Q28]
ldp q30, q31, [x0, #CTX_FP_Q30]
ldr x9, [x0, #CTX_FP_FPSR]
msr fpsr, x9
ldr x10, [x0, #CTX_FP_FPCR]
msr fpcr, x10
/*
* No explict ISB required here as ERET to
* switch to secure EL1 or non-secure world
* covers it
*/
ret
endfunc fpregs_context_restore
#endif /* CTX_INCLUDE_FPREGS */
2、sava/restore函数的应用场景
（1）、sync_exception_aarch64 //同步异常，调用smc指令后将进入这里
sync_exception_aarch64—>handle_sync_exception—>smc_handler64—>opteed_smc_handler
a . 先(仅仅)保存了x4-x7, x18, sp_el0
stp x4, x5, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X4]
stp x6, x7, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X6]
/* Save rest of the gpregs and sp_el0*/
save_x18_to_x29_sp_el0
b. 保存一个os的系统寄存器，恢复另外一个os的系统寄存器
在opteed_smc_handler中：
如果是ATF----->TEE：
cm_el1_sysregs_context_save(NON_SECURE);
cm_el1_sysregs_context_restore(SECURE);
如果是ATF----->REE：
cm_el1_sysregs_context_save(SECURE);
cm_el1_sysregs_context_restore(NON_SECURE);
c. 恢复通用寄存器
在opteed_smc_handler处理完毕后，再回到smc_handler64，调用el3_exit
在el3_exit中，先恢复gp寄存器，再eret恢复pc/pstate，返回到执行smc触发同步异常的地方
restore_gp_registers_eret
（2）、irq_aarch64 //atf中的同步异常
irq_aarch64 —>handle_interrupt_exception----->中断函数处理—>el3_exit
先调用save_gp_registers保存通用寄存器，然后进行中断函数处理
再在el3_exit中调用restore_gp_registers_eret恢复通用寄存器