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Commit 5a343b9f authored by Vineet Gupta's avatar Vineet Gupta
Browse files

ARC: entry.S: [arcompact] simplify SWITCH_TO_KERNEL_STK 



Previously this macro was overloaded with stack switching, saving SP at right
slot in pt_regs, saving/setup of r25 and setting SP baseline to where
pt_regs->sp is saved (vs. bottom of pt_regs)

Now it only does SP switch, and leaves SP pointing to bottom of pt_regs.

r25 saving is no longer done here to allow for future reordering of
regfile in pt_regs w/o touching this macro

Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
parent c80417b6

arch/arc/include/asm/entry-compact.h

+35 −36
Original line number Diff line number Diff line
@@ -39,8 +39,8 @@ 
 * Switch to Kernel Mode stack if SP points to User Mode stack

 *

 * Entry   : r9 contains pre-IRQ/exception/trap status32

 * Exit    : SP is set to kernel mode stack pointer

 *           If CURR_IN_REG, r25 set to "current" task pointer

 * Exit    : SP set to K mode stack

 *           SP at the time of entry (K/U) saved @ pt_regs->sp

 * Clobbers: r9

 *-------------------------------------------------------------*/
@@ -80,12 +80,11 @@ 


#endif



	/* Save Pre Intr/Exception KERNEL MODE SP on kernel stack

	 * safe-keeping not really needed, but it keeps the epilogue code

	 * (SP restore) simpler/uniform.

	 */

    /*------Intr/Ecxp happened in kernel mode, SP already setup ------ */

	/* save it nevertheless @ pt_regs->sp for uniformity */



	b.d	66f

	mov	r9, sp

	st	sp, [sp, PT_sp - SZ_PT_REGS]



88: /*------Intr/Ecxp happened in user mode, "switch" stack ------ */
@@ -94,30 +93,12 @@ 
	/* With current tsk in r9, get it's kernel mode stack base */

	GET_TSK_STACK_BASE  r9, r9



66:

#ifdef CONFIG_ARC_CURR_IN_REG

	/*

	 * Treat r25 as scratch reg, save it on stack first

	 * Load it with current task pointer

	 */

	st	r25, [r9, -4]

	GET_CURR_TASK_ON_CPU   r25

#endif



	/* Save Pre Intr/Exception User SP on kernel stack */

	st.a    sp, [r9, -16]	; Make room for orig_r0, ECR, user_r25



	/* CAUTION:

	 * SP should be set at the very end when we are done with everything

	 * In case of 2 levels of interrupt we depend on value of SP to assume

	 * that everything else is done (loading r25 etc)

	 */

	/* save U mode SP @ pt_regs->sp */

	st	sp, [r9, PT_sp - SZ_PT_REGS]



	/* set SP to point to kernel mode stack */

	/* final SP switch */

	mov	sp, r9



	/* ----- Stack Switched to kernel Mode, Now save REG FILE ----- */



66:

.endm



/*------------------------------------------------------------
@@ -181,11 +162,21 @@ 
	/* ARC700 doesn't provide auto-stack switching */

	SWITCH_TO_KERNEL_STK



	st      r0, [sp, 4]    /* orig_r0, needed only for sys calls */

#ifdef CONFIG_ARC_CURR_IN_REG

	/* Treat r25 as scratch reg (save on stack) and load with "current" */

	PUSH    r25

	GET_CURR_TASK_ON_CPU   r25

#else

	sub     sp, sp, 4

#endif



	st.a	r0, [sp, -8]    /* orig_r0 needed for syscall (skip ECR slot) */

	sub	sp, sp, 4	/* skip pt_regs->sp, already saved above */



	/* Restore r9 used to code the early prologue */

	PROLOG_RESTORE_REG  r9, @ex_saved_reg1



	/* now we are ready to save the regfile */

	SAVE_R0_TO_R12

	PUSH	gp

	PUSH	fp
@@ -245,12 +236,20 @@ 


	SWITCH_TO_KERNEL_STK



	/* restore original r9 */

	PROLOG_RESTORE_REG  r9, @int\LVL\()_saved_reg

#ifdef CONFIG_ARC_CURR_IN_REG

	/* Treat r25 as scratch reg (save on stack) and load with "current" */

	PUSH    r25

	GET_CURR_TASK_ON_CPU   r25

#else

	sub     sp, sp, 4

#endif



	/* now we are ready to save the remaining context */

	st	0x003\LVL\()abcd, [sp, 8]    /* Dummy ECR */

	st      0, [sp, 4]    /* orig_r0 , N/A for IRQ */

	PUSH	0x003\LVL\()abcd    /* Dummy ECR */

	sub	sp, sp, 8	    /* skip orig_r0 (not needed)

				       skip pt_regs->sp, already saved above */



	/* Restore r9 used to code the early prologue */

	PROLOG_RESTORE_REG  r9, @int\LVL\()_saved_reg



	SAVE_R0_TO_R12

	PUSH	gp