arch/arc/core/userspace.S - third_party/github/zephyrproject-rtos/zephyr - Git at Google

 /*
  * Copyright (c) 2018 Synopsys.
  *
  * SPDX-License-Identifier: Apache-2.0
  */

 #include <offsets_short.h>
 #include <zephyr/toolchain.h>
 #include <zephyr/linker/sections.h>
 #include <zephyr/kernel_structs.h>
 #include <zephyr/arch/cpu.h>
 #include <zephyr/syscall.h>
 #include <swap_macros.h>
 #include <v2/irq.h>

 .macro clear_scratch_regs
 	mov_s r1, 0
 	mov_s r2, 0
 	mov_s r3, 0
 	mov_s r4, 0
 	mov_s r5, 0
 	mov_s r6, 0
 	mov_s r7, 0
 	mov_s r8, 0
 	mov_s r9, 0
 	mov_s r10, 0
 	mov_s r11, 0
 	mov_s r12, 0
 .endm

 .macro clear_callee_regs
 	mov_s r25, 0
 	mov_s r24, 0
 	mov_s r23, 0
 	mov_s r22, 0
 	mov_s r21, 0
 	mov_s r20, 0
 	mov_s r19, 0
 	mov_s r18, 0
 	mov_s r17, 0
 	mov_s r16, 0

 	mov_s r15, 0
 	mov_s r14, 0
 	mov_s r13, 0
 .endm

 GTEXT(z_arc_userspace_enter)
 GTEXT(_arc_do_syscall)
 GTEXT(z_user_thread_entry_wrapper)
 GTEXT(arch_user_string_nlen)
 GTEXT(z_arc_user_string_nlen_fault_start)
 GTEXT(z_arc_user_string_nlen_fault_end)
 GTEXT(z_arc_user_string_nlen_fixup)

 /**
  * @brief Wrapper for z_thread_entry in the case of user thread
  *
  * The init parameters are in privileged stack
  */
 SECTION_FUNC(TEXT, z_user_thread_entry_wrapper)
 	seti _ARC_V2_INIT_IRQ_LOCK_KEY
 	pop_s r3
 	pop_s r2
 	pop_s r1
 	pop_s r0
 /* the start of user sp is in r5 */
 	pop r5
 /* start of privilege stack in blink */
 	mov_s blink, sp

 	st.aw r0, [r5, -4]
 	st.aw r1, [r5, -4]
 	st.aw r2, [r5, -4]
 	st.aw r3, [r5, -4]

 /*
  * when CONFIG_INIT_STACKS is enable, stack will be initialized
  * in z_new_thread_init.
  */
 	j _arc_go_to_user_space

 /**
  *
  * User space entry function
  *
  * This function is the entry point to user mode from privileged execution.
  * The conversion is one way, and threads which transition to user mode do
  * not transition back later, unless they are doing system calls.
  *
  */
 SECTION_FUNC(TEXT, z_arc_userspace_enter)
 	/*
 	 * In ARCv2, the U bit can only be set through exception return
 	 */
 	/* disable stack checking as the stack should be initialized */
 	_disable_stack_checking blink

 	/* the end of user stack in r5 */
 	add r5, r4, r5
 	/* get start of privilege stack, r6 points to current thread */
 	ld blink, [r6, _thread_offset_to_priv_stack_start]
 	add blink, blink, CONFIG_PRIVILEGED_STACK_SIZE

 	mov_s sp, r5

 	push_s r0
 	push_s r1
 	push_s r2
 	push_s r3

 	mov r5, sp /* skip r0, r1, r2, r3 */

 /* to avoid the leakage of kernel info, the thread stack needs to be
  * re-initialized
  */
 #ifdef CONFIG_INIT_STACKS
 	mov_s r0, 0xaaaaaaaa
 #else
 	mov_s r0, 0x0
 #endif
 _clear_user_stack:
 	st.ab r0, [r4, 4]
 	cmp r4, r5
 	jlt _clear_user_stack

 /* reload the stack checking regs as the original kernel stack
  * becomes user stack
  */
 #ifdef CONFIG_ARC_STACK_CHECKING
 /* current thread in r6, SMP case is also considered */
 	mov r2, r6

 	_load_stack_check_regs

 	_enable_stack_checking r0
 #endif

 /* the following codes are used to switch from kernel mode
  * to user mode by fake exception, because U bit can only be set
  * by exception
  */
 _arc_go_to_user_space:
 	lr r0, [_ARC_V2_STATUS32]
 	bset r0, r0, _ARC_V2_STATUS32_U_BIT

 	mov_s r1, z_thread_entry_wrapper1

 	sr r0, [_ARC_V2_ERSTATUS]
 	sr r1, [_ARC_V2_ERET]

 	/* fake exception return */
 	lr r0, [_ARC_V2_STATUS32]
 	bset r0, r0, _ARC_V2_STATUS32_AE_BIT
 	kflag r0

 /* when exception returns from kernel to user, sp and _ARC_V2_USER_SP
  * /_ARC_V2_SECU_SP will be switched
  */
 #if defined(CONFIG_ARC_HAS_SECURE) && defined(CONFIG_ARC_SECURE_FIRMWARE)
 	lr r0, [_ARC_V2_SEC_STAT]
 	/* the mode returns from exception return is secure mode */
 	bset r0, r0, 31
 	sr r0, [_ARC_V2_ERSEC_STAT]
 	sr r5, [_ARC_V2_SEC_U_SP]
 #else
 	sr r5, [_ARC_V2_USER_SP]
 #endif
 	mov_s sp, blink

 	mov_s r0, 0

 	clear_callee_regs

 	clear_scratch_regs

 	mov fp, 0
 	mov r29, 0
 	mov r30, 0
 	mov blink, 0

 	rtie

 /**
  *
  * Userspace system call function
  *
  * This function is used to do system calls from unprivileged code.  This
  * function is responsible for the following:
  * 1) Dispatching the system call
  * 2) Restoring stack and calling back to the caller of the system call
  *
  */
 SECTION_FUNC(TEXT, _arc_do_syscall)
 	/*
 	 * r0-r5: arg1-arg6, r6 is call id which is already checked in
 	 * trap_s handler, r7 is the system call stack frame pointer
 	 * need to recover r0, r1, r2 because they will be modified in
 	 * _create_irq_stack_frame. If a specific syscall frame (different
 	 * with irq stack frame) is defined, the cover of r0, r1, r2 can be
 	 * optimized.
 	 */
 	ld_s r0, [sp, ___isf_t_r0_OFFSET]
 	ld_s r1, [sp, ___isf_t_r1_OFFSET]
 	ld_s r2, [sp, ___isf_t_r2_OFFSET]

 	mov r7, sp

 	mov_s blink, _k_syscall_table
 	ld.as r6, [blink, r6]

 	jl [r6]

 	/* save return value */
 	st_s r0, [sp, ___isf_t_r0_OFFSET]

 	mov r29, 0
 	mov r30, 0

 	/* through fake exception return, go back to the caller */
 	lr r0, [_ARC_V2_STATUS32]
 	bset r0, r0, _ARC_V2_STATUS32_AE_BIT
 	kflag r0


 #ifdef CONFIG_ARC_SECURE_FIRMWARE
 	ld_s r0, [sp, ___isf_t_sec_stat_OFFSET]
 	sr r0,[_ARC_V2_ERSEC_STAT]
 #endif
 	ld_s r0, [sp, ___isf_t_status32_OFFSET]
 	sr r0,[_ARC_V2_ERSTATUS]

 	ld_s r0, [sp, ___isf_t_pc_OFFSET] /* eret into pc */
 	sr r0,[_ARC_V2_ERET]

 	_pop_irq_stack_frame

 	rtie

 /*
  * size_t arch_user_string_nlen(const char *s, size_t maxsize, int *err_arg)
  */
 SECTION_FUNC(TEXT, arch_user_string_nlen)
 	/* int err; */
 	sub_s sp,sp,0x4

 	/* Initial error value (-1 failure), store at [sp,0] */
 	mov_s r3, -1
 	st_s r3, [sp, 0]

 	/* Loop setup.
 	 * r12 (position locator) = s - 1
 	 * r0 (length counter return value)) = 0
 	 * lp_count = maxsize + 1
 	 * */
 	sub r12, r0, 0x1
 	mov_s r0, 0
 	add_s r1, r1, 1
 	mov lp_count, r1

 strlen_loop:
 z_arc_user_string_nlen_fault_start:
 	/* is the byte at ++r12 a NULL? if so, we're done. Might fault! */
 	ldb.aw r1, [r12, 1]

 z_arc_user_string_nlen_fault_end:
 	brne_s r1, 0, not_null

 strlen_done:
 	/* Success, set err to 0 */
 	mov_s r1, 0
 	st_s r1, [sp, 0]

 z_arc_user_string_nlen_fixup:
 	/* *err_arg = err; Pop stack and return */
 	ld_s r1, [sp, 0]
 	add_s sp, sp, 4
 	j_s.d [blink]
 	st_s r1, [r2, 0]

 not_null:
 	/* check if we've hit the maximum, if so we're done. */
 	brne.d.nt lp_count, 0x1, inc_len
 	sub lp_count, lp_count, 0x1
 	b_s strlen_done

 inc_len:
 	/* increment length measurement, loop again */
 	add_s r0, r0, 1
 	b_s strlen_loop
	/*
	* Copyright (c) 2018 Synopsys.
	*
	* SPDX-License-Identifier: Apache-2.0
	*/

	#include <offsets_short.h>
	#include <zephyr/toolchain.h>
	#include <zephyr/linker/sections.h>
	#include <zephyr/kernel_structs.h>
	#include <zephyr/arch/cpu.h>
	#include <zephyr/syscall.h>
	#include <swap_macros.h>
	#include <v2/irq.h>

	.macro clear_scratch_regs
	mov_s r1, 0
	mov_s r2, 0
	mov_s r3, 0
	mov_s r4, 0
	mov_s r5, 0
	mov_s r6, 0
	mov_s r7, 0
	mov_s r8, 0
	mov_s r9, 0
	mov_s r10, 0
	mov_s r11, 0
	mov_s r12, 0
	.endm

	.macro clear_callee_regs
	mov_s r25, 0
	mov_s r24, 0
	mov_s r23, 0
	mov_s r22, 0
	mov_s r21, 0
	mov_s r20, 0
	mov_s r19, 0
	mov_s r18, 0
	mov_s r17, 0
	mov_s r16, 0

	mov_s r15, 0
	mov_s r14, 0
	mov_s r13, 0
	.endm

	GTEXT(z_arc_userspace_enter)
	GTEXT(_arc_do_syscall)
	GTEXT(z_user_thread_entry_wrapper)
	GTEXT(arch_user_string_nlen)
	GTEXT(z_arc_user_string_nlen_fault_start)
	GTEXT(z_arc_user_string_nlen_fault_end)
	GTEXT(z_arc_user_string_nlen_fixup)

	/**
	* @brief Wrapper for z_thread_entry in the case of user thread
	*
	* The init parameters are in privileged stack
	*/
	SECTION_FUNC(TEXT, z_user_thread_entry_wrapper)
	seti _ARC_V2_INIT_IRQ_LOCK_KEY
	pop_s r3
	pop_s r2
	pop_s r1
	pop_s r0
	/* the start of user sp is in r5 */
	pop r5
	/* start of privilege stack in blink */
	mov_s blink, sp

	st.aw r0, [r5, -4]
	st.aw r1, [r5, -4]
	st.aw r2, [r5, -4]
	st.aw r3, [r5, -4]

	/*
	* when CONFIG_INIT_STACKS is enable, stack will be initialized
	* in z_new_thread_init.
	*/
	j _arc_go_to_user_space

	/**
	*
	* User space entry function
	*
	* This function is the entry point to user mode from privileged execution.
	* The conversion is one way, and threads which transition to user mode do
	* not transition back later, unless they are doing system calls.
	*
	*/
	SECTION_FUNC(TEXT, z_arc_userspace_enter)
	/*
	* In ARCv2, the U bit can only be set through exception return
	*/
	/* disable stack checking as the stack should be initialized */
	_disable_stack_checking blink

	/* the end of user stack in r5 */
	add r5, r4, r5
	/* get start of privilege stack, r6 points to current thread */
	ld blink, [r6, _thread_offset_to_priv_stack_start]
	add blink, blink, CONFIG_PRIVILEGED_STACK_SIZE

	mov_s sp, r5

	push_s r0
	push_s r1
	push_s r2
	push_s r3

	mov r5, sp /* skip r0, r1, r2, r3 */

	/* to avoid the leakage of kernel info, the thread stack needs to be
	* re-initialized
	*/
	#ifdef CONFIG_INIT_STACKS
	mov_s r0, 0xaaaaaaaa
	#else
	mov_s r0, 0x0
	#endif
	_clear_user_stack:
	st.ab r0, [r4, 4]
	cmp r4, r5
	jlt _clear_user_stack

	/* reload the stack checking regs as the original kernel stack
	* becomes user stack
	*/
	#ifdef CONFIG_ARC_STACK_CHECKING
	/* current thread in r6, SMP case is also considered */
	mov r2, r6

	_load_stack_check_regs

	_enable_stack_checking r0
	#endif

	/* the following codes are used to switch from kernel mode
	* to user mode by fake exception, because U bit can only be set
	* by exception
	*/
	_arc_go_to_user_space:
	lr r0, [_ARC_V2_STATUS32]
	bset r0, r0, _ARC_V2_STATUS32_U_BIT

	mov_s r1, z_thread_entry_wrapper1

	sr r0, [_ARC_V2_ERSTATUS]
	sr r1, [_ARC_V2_ERET]

	/* fake exception return */
	lr r0, [_ARC_V2_STATUS32]
	bset r0, r0, _ARC_V2_STATUS32_AE_BIT
	kflag r0

	/* when exception returns from kernel to user, sp and _ARC_V2_USER_SP
	* /_ARC_V2_SECU_SP will be switched
	*/
	#if defined(CONFIG_ARC_HAS_SECURE) && defined(CONFIG_ARC_SECURE_FIRMWARE)
	lr r0, [_ARC_V2_SEC_STAT]
	/* the mode returns from exception return is secure mode */
	bset r0, r0, 31
	sr r0, [_ARC_V2_ERSEC_STAT]
	sr r5, [_ARC_V2_SEC_U_SP]
	#else
	sr r5, [_ARC_V2_USER_SP]
	#endif
	mov_s sp, blink

	mov_s r0, 0

	clear_callee_regs

	clear_scratch_regs

	mov fp, 0
	mov r29, 0
	mov r30, 0
	mov blink, 0

	rtie

	/**
	*
	* Userspace system call function
	*
	* This function is used to do system calls from unprivileged code. This
	* function is responsible for the following:
	* 1) Dispatching the system call
	* 2) Restoring stack and calling back to the caller of the system call
	*
	*/
	SECTION_FUNC(TEXT, _arc_do_syscall)
	/*
	* r0-r5: arg1-arg6, r6 is call id which is already checked in
	* trap_s handler, r7 is the system call stack frame pointer
	* need to recover r0, r1, r2 because they will be modified in
	* _create_irq_stack_frame. If a specific syscall frame (different
	* with irq stack frame) is defined, the cover of r0, r1, r2 can be
	* optimized.
	*/
	ld_s r0, [sp, ___isf_t_r0_OFFSET]
	ld_s r1, [sp, ___isf_t_r1_OFFSET]
	ld_s r2, [sp, ___isf_t_r2_OFFSET]

	mov r7, sp

	mov_s blink, _k_syscall_table
	ld.as r6, [blink, r6]

	jl [r6]

	/* save return value */
	st_s r0, [sp, ___isf_t_r0_OFFSET]

	mov r29, 0
	mov r30, 0

	/* through fake exception return, go back to the caller */
	lr r0, [_ARC_V2_STATUS32]
	bset r0, r0, _ARC_V2_STATUS32_AE_BIT
	kflag r0


	#ifdef CONFIG_ARC_SECURE_FIRMWARE
	ld_s r0, [sp, ___isf_t_sec_stat_OFFSET]
	sr r0,[_ARC_V2_ERSEC_STAT]
	#endif
	ld_s r0, [sp, ___isf_t_status32_OFFSET]
	sr r0,[_ARC_V2_ERSTATUS]

	ld_s r0, [sp, ___isf_t_pc_OFFSET] /* eret into pc */
	sr r0,[_ARC_V2_ERET]

	_pop_irq_stack_frame

	rtie

	/*
	* size_t arch_user_string_nlen(const char s, size_t maxsize, int err_arg)
	*/
	SECTION_FUNC(TEXT, arch_user_string_nlen)
	/* int err; */
	sub_s sp,sp,0x4

	/* Initial error value (-1 failure), store at [sp,0] */
	mov_s r3, -1
	st_s r3, [sp, 0]

	/* Loop setup.
	* r12 (position locator) = s - 1
	* r0 (length counter return value)) = 0
	* lp_count = maxsize + 1
	* */
	sub r12, r0, 0x1
	mov_s r0, 0
	add_s r1, r1, 1
	mov lp_count, r1

	strlen_loop:
	z_arc_user_string_nlen_fault_start:
	/* is the byte at ++r12 a NULL? if so, we're done. Might fault! */
	ldb.aw r1, [r12, 1]

	z_arc_user_string_nlen_fault_end:
	brne_s r1, 0, not_null

	strlen_done:
	/* Success, set err to 0 */
	mov_s r1, 0
	st_s r1, [sp, 0]

	z_arc_user_string_nlen_fixup:
	/* err_arg = err; Pop stack and return /
	ld_s r1, [sp, 0]
	add_s sp, sp, 4
	j_s.d [blink]
	st_s r1, [r2, 0]

	not_null:
	/* check if we've hit the maximum, if so we're done. */
	brne.d.nt lp_count, 0x1, inc_len
	sub lp_count, lp_count, 0x1
	b_s strlen_done

	inc_len:
	/* increment length measurement, loop again */
	add_s r0, r0, 1
	b_s strlen_loop