Commit 16f9afe6 authored by Vineet Gupta's avatar Vineet Gupta
Browse files

ARC: pt_regs update #3: Remove unused gutter at start of callee_regs 



This is trickier than prev two:

* context switching code saves kernel mode callee regs in the format of
  struct callee_regs thus needs adjustment. This also reduces the height
  of topmost kernel stack frame by 1 word.

* Since kernel stack unwinder is sensitive to height of topmost kernel
  stack frame, that needs a word of adjustment too.

ptrace needs a bit of updating since pt_regs now diverges from
user_regs_struct.

Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
parent 2fa91904

arch/arc/include/asm/entry.h

+3 −11
Original line number Diff line number Diff line
@@ -124,8 +124,6 @@ 
	st.a    r25, [sp, -4]

#endif



	/* move up by 1 word to "create" callee_regs->"stack_place_holder" */

	sub sp, sp, 4

.endm



/*--------------------------------------------------------------
@@ -148,10 +146,9 @@ 
	st.a    r23, [sp, -4]

	st.a    r24, [sp, -4]

#ifdef CONFIG_ARC_CURR_IN_REG

	sub     sp, sp, 8

	sub     sp, sp, 4

#else

	st.a    r25, [sp, -4]

	sub     sp, sp, 4

#endif

.endm
@@ -168,14 +165,11 @@ 
 *-------------------------------------------------------------*/

.macro RESTORE_CALLEE_SAVED_KERNEL





#ifdef CONFIG_ARC_CURR_IN_REG

	add     sp, sp, 8  /* skip callee_reg gutter and user r25 placeholder */

	add     sp, sp, 4  /* skip usual r25 placeholder */

#else

	add     sp, sp, 4   /* skip "callee_regs->stack_place_holder" */

	ld.ab   r25, [sp, 4]

#endif



	ld.ab   r24, [sp, 4]

	ld.ab   r23, [sp, 4]

	ld.ab   r22, [sp, 4]
@@ -203,8 +197,6 @@ 
 *-------------------------------------------------------------*/

.macro RESTORE_CALLEE_SAVED_USER



	add     sp, sp, 4   /* skip "callee_regs->stack_place_holder" */



#ifdef CONFIG_ARC_CURR_IN_REG

	ld.ab   r12, [sp, 4]

	st      r12, [r25, TASK_THREAD + THREAD_USER_R25]
@@ -230,7 +222,7 @@ 
 * Super FAST Restore callee saved regs by simply re-adjusting SP

 *-------------------------------------------------------------*/

.macro DISCARD_CALLEE_SAVED_USER

	add     sp, sp, 14 * 4

	add     sp, sp, SZ_CALLEE_REGS

.endm



/*--------------------------------------------------------------

arch/arc/include/asm/processor.h

+8 −3
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 
#ifndef __ASSEMBLY__



#include <asm/arcregs.h>	/* for STATUS_E1_MASK et all */

#include <asm/ptrace.h>



/* Arch specific stuff which needs to be saved per task.

 * However these items are not so important so as to earn a place in
@@ -75,11 +76,15 @@ unsigned long thread_saved_pc(struct task_struct *t); 


/*

 * Where abouts of Task's sp, fp, blink when it was last seen in kernel mode.

 * These can't be derived from pt_regs as that would give correp user-mode val

 * Look in process.c for details of kernel stack layout

 */

#define KSTK_ESP(tsk)   (tsk->thread.ksp)

#define KSTK_BLINK(tsk) (*((unsigned int *)((KSTK_ESP(tsk)) + (13+1+1)*4)))

#define KSTK_FP(tsk)    (*((unsigned int *)((KSTK_ESP(tsk)) + (13+1)*4)))



#define KSTK_REG(tsk, off)	(*((unsigned int *)(KSTK_ESP(tsk) + \

					sizeof(struct callee_regs) + off)))



#define KSTK_BLINK(tsk) KSTK_REG(tsk, 4)

#define KSTK_FP(tsk)    KSTK_REG(tsk, 0)



/*

 * Do necessary setup to start up a newly executed thread.

arch/arc/include/asm/ptrace.h

+0 −1
Original line number Diff line number Diff line
@@ -59,7 +59,6 @@ struct pt_regs { 
/* Callee saved registers - need to be saved only when you are scheduled out */



struct callee_regs {

	long res;	/* Again this is not needed */

	long r25;

	long r24;

	long r23;

arch/arc/include/uapi/asm/ptrace.h

+1 −1
Original line number Diff line number Diff line
@@ -38,8 +38,8 @@ struct user_regs_struct { 
		long r12, r11, r10, r9, r8, r7, r6, r5, r4, r3, r2, r1, r0;

		long sp;

	} scratch;

	long pad2;

	struct {

		long pad;

		long r25, r24, r23, r22, r21, r20;

		long r19, r18, r17, r16, r15, r14, r13;

	} callee;

arch/arc/kernel/asm-offsets.c

+1 −0
Original line number Diff line number Diff line
@@ -60,5 +60,6 @@ int main(void) 
	DEFINE(PT_r6, offsetof(struct pt_regs, r6));

	DEFINE(PT_r7, offsetof(struct pt_regs, r7));



	DEFINE(SZ_CALLEE_REGS, sizeof(struct callee_regs));

	return 0;

}

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