cregit-Linux how code gets into the kernel

Release 4.14 arch/powerpc/kernel/head_booke.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __HEAD_BOOKE_H__

#define __HEAD_BOOKE_H__

#include <asm/ptrace.h>	/* for STACK_FRAME_REGS_MARKER */
#include <asm/kvm_asm.h>
#include <asm/kvm_booke_hv_asm.h>

/*
 * Macros used for common Book-e exception handling
 */


#define SET_IVOR(vector_number, vector_label)		\
		li      r26,vector_label@l;             \
                mtspr   SPRN_IVOR##vector_number,r26;   \
                sync

#if (THREAD_SHIFT < 15)

#define ALLOC_STACK_FRAME(reg, val)			\
	addi reg,reg,val
#else

#define ALLOC_STACK_FRAME(reg, val)			\
	addis   reg,reg,val@ha;                         \
        addi    reg,reg,val@l
#endif

/*
 * Macro used to get to thread save registers.
 * Note that entries 0-3 are used for the prolog code, and the remaining
 * entries are available for specific exception use in the event a handler
 * requires more than 4 scratch registers.
 */

#define THREAD_NORMSAVE(offset)	(THREAD_NORMSAVES + (offset * 4))


#define NORMAL_EXCEPTION_PROLOG(intno)						     \
	mtspr   SPRN_SPRG_WSCRATCH0, r10;	/* save one register */	     \
        mfspr   r10, SPRN_SPRG_THREAD;                                       \
        stw     r11, THREAD_NORMSAVE(0)(r10);                                \
        stw     r13, THREAD_NORMSAVE(2)(r10);                                \
        mfcr    r13;			/* save CR in r13 for now          */\
        mfspr   r11, SPRN_SRR1;                                              \
        DO_KVM  BOOKE_INTERRUPT_##intno SPRN_SRR1;                           \
        andi.   r11, r11, MSR_PR;	/* check whether user or kernel    */\
        mr      r11, r1;                                                     \
        beq     1f;                                                          \
	/* if from user, start at top of this thread's kernel stack */       \
        lwz     r11, THREAD_INFO-THREAD(r10);                                \
        ALLOC_STACK_FRAME(r11, THREAD_SIZE);                                 \
1 :     subi    r11, r11, INT_FRAME_SIZE; /* Allocate exception frame */     \
        stw     r13, _CCR(r11);		/* save various registers */	     \
        stw     r12,GPR12(r11);                                              \
        stw     r9,GPR9(r11);                                                \
        mfspr   r13, SPRN_SPRG_RSCRATCH0;                                    \
        stw     r13, GPR10(r11);                                             \
        lwz     r12, THREAD_NORMSAVE(0)(r10);                                \
        stw     r12,GPR11(r11);                                              \
        lwz     r13, THREAD_NORMSAVE(2)(r10); /* restore r13 */		     \
        mflr    r10;                                                         \
        stw     r10,_LINK(r11);                                              \
        mfspr   r12,SPRN_SRR0;                                               \
        stw     r1, GPR1(r11);                                               \
        mfspr   r9,SPRN_SRR1;                                                \
        stw     r1, 0(r11);                                                  \
        mr      r1, r11;                                                     \
        rlwinm  r9,r9,0,14,12;		/* clear MSR_WE (necessary?)       */\
        stw     r0,GPR0(r11);                                                \
        lis     r10, STACK_FRAME_REGS_MARKER@ha;/* exception frame marker */ \
        addi    r10, r10, STACK_FRAME_REGS_MARKER@l;                         \
        stw     r10, 8(r11);                                                 \
        SAVE_4GPRS(3, r11);                                                  \
        SAVE_2GPRS(7, r11)

/* To handle the additional exception priority levels on 40x and Book-E
 * processors we allocate a stack per additional priority level.
 *
 * On 40x critical is the only additional level
 * On 44x/e500 we have critical and machine check
 * On e200 we have critical and debug (machine check occurs via critical)
 *
 * Additionally we reserve a SPRG for each priority level so we can free up a
 * GPR to use as the base for indirect access to the exception stacks.  This
 * is necessary since the MMU is always on, for Book-E parts, and the stacks
 * are offset from KERNELBASE.
 *
 * There is some space optimization to be had here if desired.  However
 * to allow for a common kernel with support for debug exceptions either
 * going to critical or their own debug level we aren't currently
 * providing configurations that micro-optimize space usage.
 */


#define MC_STACK_BASE		mcheckirq_ctx

#define CRIT_STACK_BASE		critirq_ctx

/* only on e500mc/e200 */

#define DBG_STACK_BASE		dbgirq_ctx


#define EXC_LVL_FRAME_OVERHEAD	(THREAD_SIZE - INT_FRAME_SIZE - EXC_LVL_SIZE)

#ifdef CONFIG_SMP

#define BOOKE_LOAD_EXC_LEVEL_STACK(level)		\
	mfspr   r8,SPRN_PIR;                            \
        slwi    r8,r8,2;                                \
        addis   r8,r8,level##_STACK_BASE@ha;            \
        lwz     r8,level##_STACK_BASE@l(r8);            \
        addi    r8,r8,EXC_LVL_FRAME_OVERHEAD;
#else

#define BOOKE_LOAD_EXC_LEVEL_STACK(level)		\
	lis     r8,level##_STACK_BASE@ha;               \
        lwz     r8,level##_STACK_BASE@l(r8);            \
        addi    r8,r8,EXC_LVL_FRAME_OVERHEAD;
#endif

/*
 * Exception prolog for critical/machine check exceptions.  This is a
 * little different from the normal exception prolog above since a
 * critical/machine check exception can potentially occur at any point
 * during normal exception processing. Thus we cannot use the same SPRG
 * registers as the normal prolog above. Instead we use a portion of the
 * critical/machine check exception stack at low physical addresses.
 */

#define EXC_LEVEL_EXCEPTION_PROLOG(exc_level, intno, exc_level_srr0, exc_level_srr1) \
	mtspr   SPRN_SPRG_WSCRATCH_##exc_level,r8;                           \
        BOOKE_LOAD_EXC_LEVEL_STACK(exc_level);/* r8 points to the exc_level stack*/ \
        stw     r9,GPR9(r8);		/* save various registers          */\
        mfcr    r9;			/* save CR in r9 for now           */\
        stw     r10,GPR10(r8);                                               \
        stw     r11,GPR11(r8);                                               \
        stw     r9,_CCR(r8);		/* save CR on stack                */\
        mfspr   r11,exc_level_srr1;	/* check whether user or kernel    */\
        DO_KVM  BOOKE_INTERRUPT_##intno exc_level_srr1;                      \
        andi.   r11,r11,MSR_PR;                                              \
        mfspr   r11,SPRN_SPRG_THREAD;	/* if from user, start at top of   */\
        lwz     r11,THREAD_INFO-THREAD(r11); /* this thread's kernel stack */\
        addi    r11,r11,EXC_LVL_FRAME_OVERHEAD;	/* allocate stack frame    */\
        beq     1f;                                                          \
	/* COMING FROM USER MODE */					     \
        stw     r9,_CCR(r11);		/* save CR                         */\
        lwz     r10,GPR10(r8);		/* copy regs from exception stack  */\
        lwz     r9,GPR9(r8);                                                 \
        stw     r10,GPR10(r11);                                              \
        lwz     r10,GPR11(r8);                                               \
        stw     r9,GPR9(r11);                                                \
        stw     r10,GPR11(r11);                                              \
        b       2f;                                                          \
	/* COMING FROM PRIV MODE */					     \
1:      lwz     r9,TI_FLAGS-EXC_LVL_FRAME_OVERHEAD(r11);                     \
        lwz     r10,TI_PREEMPT-EXC_LVL_FRAME_OVERHEAD(r11);                  \
        stw     r9,TI_FLAGS-EXC_LVL_FRAME_OVERHEAD(r8);                      \
        stw     r10,TI_PREEMPT-EXC_LVL_FRAME_OVERHEAD(r8);                   \
        lwz     r9,TI_TASK-EXC_LVL_FRAME_OVERHEAD(r11);                      \
        stw     r9,TI_TASK-EXC_LVL_FRAME_OVERHEAD(r8);                       \
        mr      r11,r8;                                                      \
2:      mfspr   r8,SPRN_SPRG_RSCRATCH_##exc_level;                           \
        stw     r12,GPR12(r11);		/* save various registers          */\
        mflr    r10;                                                         \
        stw     r10,_LINK(r11);                                              \
        mfspr   r12,SPRN_DEAR;		/* save DEAR and ESR in the frame  */\
        stw     r12,_DEAR(r11);		/* since they may have had stuff   */\
        mfspr   r9,SPRN_ESR;		/* in them at the point where the  */\
        stw     r9,_ESR(r11);		/* exception was taken             */\
        mfspr   r12,exc_level_srr0;                                          \
        stw     r1,GPR1(r11);                                                \
        mfspr   r9,exc_level_srr1;                                           \
        stw     r1,0(r11);                                                   \
        mr      r1,r11;                                                      \
        rlwinm  r9,r9,0,14,12;		/* clear MSR_WE (necessary?)       */\
        stw     r0,GPR0(r11);                                                \
        SAVE_4GPRS(3, r11);                                                  \
        SAVE_2GPRS(7, r11)


#define CRITICAL_EXCEPTION_PROLOG(intno) \
		EXC_LEVEL_EXCEPTION_PROLOG(CRIT, intno, SPRN_CSRR0, SPRN_CSRR1)

#define DEBUG_EXCEPTION_PROLOG \
		EXC_LEVEL_EXCEPTION_PROLOG(DBG, DEBUG, SPRN_DSRR0, SPRN_DSRR1)

#define MCHECK_EXCEPTION_PROLOG \
		EXC_LEVEL_EXCEPTION_PROLOG(MC, MACHINE_CHECK, \
                        SPRN_MCSRR0, SPRN_MCSRR1)

/*
 * Guest Doorbell -- this is a bit odd in that uses GSRR0/1 despite
 * being delivered to the host.  This exception can only happen
 * inside a KVM guest -- so we just handle up to the DO_KVM rather
 * than try to fit this into one of the existing prolog macros.
 */

#define GUEST_DOORBELL_EXCEPTION \
	START_EXCEPTION(GuestDoorbell);                                      \
        mtspr   SPRN_SPRG_WSCRATCH0, r10;	/* save one register */	     \
        mfspr   r10, SPRN_SPRG_THREAD;                                       \
        stw     r11, THREAD_NORMSAVE(0)(r10);                                \
        mfspr   r11, SPRN_SRR1;                                              \
        stw     r13, THREAD_NORMSAVE(2)(r10);                                \
        mfcr    r13;			/* save CR in r13 for now          */\
        DO_KVM  BOOKE_INTERRUPT_GUEST_DBELL SPRN_GSRR1;                      \
        trap

/*
 * Exception vectors.
 */

#define	START_EXCEPTION(label)						     \
        .align 5;                                                            \
label:


#define EXCEPTION(n, intno, label, hdlr, xfer)			\
	START_EXCEPTION(label);                                 \
        NORMAL_EXCEPTION_PROLOG(intno);                         \
        addi    r3,r1,STACK_FRAME_OVERHEAD;                     \
        xfer(n, hdlr)


#define CRITICAL_EXCEPTION(n, intno, label, hdlr)			\
	START_EXCEPTION(label);                                         \
        CRITICAL_EXCEPTION_PROLOG(intno);                               \
        addi    r3,r1,STACK_FRAME_OVERHEAD;                             \
        EXC_XFER_TEMPLATE(hdlr, n+2, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), \
                          NOCOPY, crit_transfer_to_handler, \
                          ret_from_crit_exc)


#define MCHECK_EXCEPTION(n, label, hdlr)			\
	START_EXCEPTION(label);                                 \
        MCHECK_EXCEPTION_PROLOG;                                \
        mfspr   r5,SPRN_ESR;                                    \
        stw     r5,_ESR(r11);                                   \
        addi    r3,r1,STACK_FRAME_OVERHEAD;                     \
        EXC_XFER_TEMPLATE(hdlr, n+4, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), \
                          NOCOPY, mcheck_transfer_to_handler,   \
                          ret_from_mcheck_exc)


#define EXC_XFER_TEMPLATE(hdlr, trap, msr, copyee, tfer, ret)	\
	li      r10,trap;                                       \
        stw     r10,_TRAP(r11);                                 \
        lis     r10,msr@h;                                      \
        ori     r10,r10,msr@l;                                  \
        copyee(r10, r9);                                        \
        bl      tfer;                                           \
        .long   hdlr;                                           \
        .long   ret


#define COPY_EE(d, s)		rlwimi d,s,0,16,16

#define NOCOPY(d, s)


#define EXC_XFER_STD(n, hdlr)		\
	EXC_XFER_TEMPLATE(hdlr, n, MSR_KERNEL, NOCOPY, transfer_to_handler_full, \
                          ret_from_except_full)


#define EXC_XFER_LITE(n, hdlr)		\
	EXC_XFER_TEMPLATE(hdlr, n+1, MSR_KERNEL, NOCOPY, transfer_to_handler, \
                          ret_from_except)


#define EXC_XFER_EE(n, hdlr)		\
	EXC_XFER_TEMPLATE(hdlr, n, MSR_KERNEL, COPY_EE, transfer_to_handler_full, \
                          ret_from_except_full)


#define EXC_XFER_EE_LITE(n, hdlr)	\
	EXC_XFER_TEMPLATE(hdlr, n+1, MSR_KERNEL, COPY_EE, transfer_to_handler, \
                          ret_from_except)

/* Check for a single step debug exception while in an exception
 * handler before state has been saved.  This is to catch the case
 * where an instruction that we are trying to single step causes
 * an exception (eg ITLB/DTLB miss) and thus the first instruction of
 * the exception handler generates a single step debug exception.
 *
 * If we get a debug trap on the first instruction of an exception handler,
 * we reset the MSR_DE in the _exception handler's_ MSR (the debug trap is
 * a critical exception, so we are using SPRN_CSRR1 to manipulate the MSR).
 * The exception handler was handling a non-critical interrupt, so it will
 * save (and later restore) the MSR via SPRN_CSRR1, which will still have
 * the MSR_DE bit set.
 */

#define DEBUG_DEBUG_EXCEPTION						      \
	START_EXCEPTION(DebugDebug);                                          \
        DEBUG_EXCEPTION_PROLOG;                                               \
                                                                              \
	/*                                                                    \
         * If there is a single step or branch-taken exception in an          \
         * exception entry sequence, it was probably meant to apply to        \
         * the code where the exception occurred (since exception entry       \
         * doesn't turn off DE automatically).  We simulate the effect        \
         * of turning off DE on entry to an exception handler by turning      \
         * off DE in the DSRR1 value and clearing the debug status.           \
         */								      \
        mfspr   r10,SPRN_DBSR;		/* check single-step/branch taken */  \
        andis.  r10,r10,(DBSR_IC|DBSR_BT)@h;                                  \
        beq+    2f;                                                           \
                                                                              \
        lis     r10,interrupt_base@h;	/* check if exception in vectors */   \
        ori     r10,r10,interrupt_base@l;                                     \
        cmplw   r12,r10;                                                      \
        blt+    2f;			/* addr below exception vectors */    \
                                                                              \
        lis     r10,interrupt_end@h;                                          \
        ori     r10,r10,interrupt_end@l;                                      \
        cmplw   r12,r10;                                                      \
        bgt+    2f;			/* addr above exception vectors */    \
                                                                              \
	/* here it looks like we got an inappropriate debug exception. */     \
1:      rlwinm  r9,r9,0,~MSR_DE;	/* clear DE in the CDRR1 value */     \
        lis     r10,(DBSR_IC|DBSR_BT)@h;	/* clear the IC event */      \
        mtspr   SPRN_DBSR,r10;                                                \
	/* restore state and get out */					      \
        lwz     r10,_CCR(r11);                                                \
        lwz     r0,GPR0(r11);                                                 \
        lwz     r1,GPR1(r11);                                                 \
        mtcrf   0x80,r10;                                                     \
        mtspr   SPRN_DSRR0,r12;                                               \
        mtspr   SPRN_DSRR1,r9;                                                \
        lwz     r9,GPR9(r11);                                                 \
        lwz     r12,GPR12(r11);                                               \
        mtspr   SPRN_SPRG_WSCRATCH_DBG,r8;                                    \
        BOOKE_LOAD_EXC_LEVEL_STACK(DBG); /* r8 points to the debug stack */ \
        lwz     r10,GPR10(r8);                                                \
        lwz     r11,GPR11(r8);                                                \
        mfspr   r8,SPRN_SPRG_RSCRATCH_DBG;                                    \
                                                                              \
        PPC_RFDI;                                                             \
        b       .;                                                            \
                                                                              \
	/* continue normal handling for a debug exception... */		      \
2:      mfspr   r4,SPRN_DBSR;                                                 \
        addi    r3,r1,STACK_FRAME_OVERHEAD;                                   \
        EXC_XFER_TEMPLATE(DebugException, 0x2008, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), NOCOPY, debug_transfer_to_handler, ret_from_debug_exc)


#define DEBUG_CRIT_EXCEPTION						      \
	START_EXCEPTION(DebugCrit);                                           \
        CRITICAL_EXCEPTION_PROLOG(DEBUG);                                     \
                                                                              \
	/*                                                                    \
         * If there is a single step or branch-taken exception in an          \
         * exception entry sequence, it was probably meant to apply to        \
         * the code where the exception occurred (since exception entry       \
         * doesn't turn off DE automatically).  We simulate the effect        \
         * of turning off DE on entry to an exception handler by turning      \
         * off DE in the CSRR1 value and clearing the debug status.           \
         */								      \
        mfspr   r10,SPRN_DBSR;		/* check single-step/branch taken */  \
        andis.  r10,r10,(DBSR_IC|DBSR_BT)@h;                                  \
        beq+    2f;                                                           \
                                                                              \
        lis     r10,interrupt_base@h;	/* check if exception in vectors */   \
        ori     r10,r10,interrupt_base@l;                                     \
        cmplw   r12,r10;                                                      \
        blt+    2f;			/* addr below exception vectors */    \
                                                                              \
        lis     r10,interrupt_end@h;                                          \
        ori     r10,r10,interrupt_end@l;                                      \
        cmplw   r12,r10;                                                      \
        bgt+    2f;			/* addr above exception vectors */    \
                                                                              \
	/* here it looks like we got an inappropriate debug exception. */     \
1:      rlwinm  r9,r9,0,~MSR_DE;	/* clear DE in the CSRR1 value */     \
        lis     r10,(DBSR_IC|DBSR_BT)@h;	/* clear the IC event */      \
        mtspr   SPRN_DBSR,r10;                                                \
	/* restore state and get out */					      \
        lwz     r10,_CCR(r11);                                                \
        lwz     r0,GPR0(r11);                                                 \
        lwz     r1,GPR1(r11);                                                 \
        mtcrf   0x80,r10;                                                     \
        mtspr   SPRN_CSRR0,r12;                                               \
        mtspr   SPRN_CSRR1,r9;                                                \
        lwz     r9,GPR9(r11);                                                 \
        lwz     r12,GPR12(r11);                                               \
        mtspr   SPRN_SPRG_WSCRATCH_CRIT,r8;                                   \
        BOOKE_LOAD_EXC_LEVEL_STACK(CRIT); /* r8 points to the debug stack */  \
        lwz     r10,GPR10(r8);                                                \
        lwz     r11,GPR11(r8);                                                \
        mfspr   r8,SPRN_SPRG_RSCRATCH_CRIT;                                   \
                                                                              \
        rfci;                                                                 \
        b       .;                                                            \
                                                                              \
	/* continue normal handling for a critical exception... */	      \
2:      mfspr   r4,SPRN_DBSR;                                                 \
        addi    r3,r1,STACK_FRAME_OVERHEAD;                                   \
        EXC_XFER_TEMPLATE(DebugException, 0x2002, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), NOCOPY, crit_transfer_to_handler, ret_from_crit_exc)


#define DATA_STORAGE_EXCEPTION						      \
	START_EXCEPTION(DataStorage)                                          \
        NORMAL_EXCEPTION_PROLOG(DATA_STORAGE);                \
        mfspr   r5,SPRN_ESR;		/* Grab the ESR and save it */	      \
        stw     r5,_ESR(r11);                                                 \
        mfspr   r4,SPRN_DEAR;		/* Grab the DEAR */		      \
        EXC_XFER_LITE(0x0300, handle_page_fault)


#define INSTRUCTION_STORAGE_EXCEPTION					      \
	START_EXCEPTION(InstructionStorage)                                   \
        NORMAL_EXCEPTION_PROLOG(INST_STORAGE);                \
        mfspr   r5,SPRN_ESR;		/* Grab the ESR and save it */	      \
        stw     r5,_ESR(r11);                                                 \
        mr      r4,r12;                 /* Pass SRR0 as arg2 */		      \
        li      r5,0;                   /* Pass zero as arg3 */		      \
        EXC_XFER_LITE(0x0400, handle_page_fault)


#define ALIGNMENT_EXCEPTION						      \
	START_EXCEPTION(Alignment)                                            \
        NORMAL_EXCEPTION_PROLOG(ALIGNMENT);                   \
        mfspr   r4,SPRN_DEAR;           /* Grab the DEAR and save it */	      \
        stw     r4,_DEAR(r11);                                                \
        addi    r3,r1,STACK_FRAME_OVERHEAD;                                   \
        EXC_XFER_EE(0x0600, alignment_exception)


#define PROGRAM_EXCEPTION						      \
	START_EXCEPTION(Program)                                              \
        NORMAL_EXCEPTION_PROLOG(PROGRAM);                     \
        mfspr   r4,SPRN_ESR;		/* Grab the ESR and save it */	      \
        stw     r4,_ESR(r11);                                                 \
        addi    r3,r1,STACK_FRAME_OVERHEAD;                                   \
        EXC_XFER_STD(0x0700, program_check_exception)


#define DECREMENTER_EXCEPTION						      \
	START_EXCEPTION(Decrementer)                                          \
        NORMAL_EXCEPTION_PROLOG(DECREMENTER);                 \
        lis     r0,TSR_DIS@h;           /* Setup the DEC interrupt mask */    \
        mtspr   SPRN_TSR,r0;		/* Clear the DEC interrupt */	      \
        addi    r3,r1,STACK_FRAME_OVERHEAD;                                   \
        EXC_XFER_LITE(0x0900, timer_interrupt)


#define FP_UNAVAILABLE_EXCEPTION					      \
	START_EXCEPTION(FloatingPointUnavailable)                             \
        NORMAL_EXCEPTION_PROLOG(FP_UNAVAIL);                  \
        beq     1f;                                                           \
        bl      load_up_fpu;		/* if from user, just load it up */   \
        b       fast_exception_return;                                        \
1:      addi    r3,r1,STACK_FRAME_OVERHEAD;                                   \
        EXC_XFER_EE_LITE(0x800, kernel_fp_unavailable_exception)

#ifndef __ASSEMBLY__

struct exception_regs {
	
unsigned long mas0;
	
unsigned long mas1;
	
unsigned long mas2;
	
unsigned long mas3;
	
unsigned long mas6;
	
unsigned long mas7;
	
unsigned long srr0;
	
unsigned long srr1;
	
unsigned long csrr0;
	
unsigned long csrr1;
	
unsigned long dsrr0;
	
unsigned long dsrr1;
	
unsigned long saved_ksp_limit;
};

/* ensure this structure is always sized to a multiple of the stack alignment */

#define STACK_EXC_LVL_FRAME_SIZE	_ALIGN_UP(sizeof (struct exception_regs), 16)

#endif /* __ASSEMBLY__ */
#endif /* __HEAD_BOOKE_H__ */

Overall Contributors

PersonTokensPropCommitsCommitProp
Becky Bruce28254.76%14.76%
Kumar Gala10320.00%733.33%
Scott Wood448.54%29.52%
Yuri Tikhonov316.02%14.76%
Ashish Kalra203.88%14.76%
Benjamin Herrenschmidt183.50%419.05%
Torez Smith71.36%14.76%
Bharat Bhushan61.17%14.76%
Roland McGrath20.39%14.76%
Greg Kroah-Hartman10.19%14.76%
Michael Neuling10.19%14.76%
Total515100.00%21100.00%
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