[U-Boot] [PATCH 1/2] powerpc/mpc85xx: Don't relocate exception vectors
Booke does not require exception vectors to be located at address zero. U-Boot was doing so anyway, simply because that's how it had been done on other PPC. The downside of this is that once the OS is loaded to address zero, the exception vectors have been overwritten -- which makes it difficult to diagnose a crash that happens after that point.
The IVOR setup and trap entry code is simplified somewhat as a result.
Also, there is no longer a need to align individual exceptions on 0x100 byte boundaries.
Signed-off-by: Scott Wood scottwood@freescale.com --- arch/powerpc/cpu/mpc85xx/start.S | 178 +++++++++++++-------------------------- include/mpc85xx.h | 4 - include/ppc_asm.tmpl | 42 +++++++++ 3 files changed, 99 insertions(+), 125 deletions(-)
diff --git a/arch/powerpc/cpu/mpc85xx/start.S b/arch/powerpc/cpu/mpc85xx/start.S index d8c9fb6..61883cb 100644 --- a/arch/powerpc/cpu/mpc85xx/start.S +++ b/arch/powerpc/cpu/mpc85xx/start.S @@ -252,39 +252,36 @@ l2_disabled: lis r1,CONFIG_SYS_MONITOR_BASE@h mtspr IVPR,r1
- lis r3,(CONFIG_SYS_MONITOR_BASE & 0xffff)@h - ori r3,r3,(CONFIG_SYS_MONITOR_BASE & 0xffff)@l - - addi r4,r3,CriticalInput - _start + _START_OFFSET + li r4,CriticalInput@l mtspr IVOR0,r4 /* 0: Critical input */ - addi r4,r3,MachineCheck - _start + _START_OFFSET + li r4,MachineCheck@l mtspr IVOR1,r4 /* 1: Machine check */ - addi r4,r3,DataStorage - _start + _START_OFFSET + li r4,DataStorage@l mtspr IVOR2,r4 /* 2: Data storage */ - addi r4,r3,InstStorage - _start + _START_OFFSET + li r4,InstStorage@l mtspr IVOR3,r4 /* 3: Instruction storage */ - addi r4,r3,ExtInterrupt - _start + _START_OFFSET + li r4,ExtInterrupt@l mtspr IVOR4,r4 /* 4: External interrupt */ - addi r4,r3,Alignment - _start + _START_OFFSET + li r4,Alignment@l mtspr IVOR5,r4 /* 5: Alignment */ - addi r4,r3,ProgramCheck - _start + _START_OFFSET + li r4,ProgramCheck@l mtspr IVOR6,r4 /* 6: Program check */ - addi r4,r3,FPUnavailable - _start + _START_OFFSET + li r4,FPUnavailable@l mtspr IVOR7,r4 /* 7: floating point unavailable */ - addi r4,r3,SystemCall - _start + _START_OFFSET + li r4,SystemCall@l mtspr IVOR8,r4 /* 8: System call */ /* 9: Auxiliary processor unavailable(unsupported) */ - addi r4,r3,Decrementer - _start + _START_OFFSET + li r4,Decrementer@l mtspr IVOR10,r4 /* 10: Decrementer */ - addi r4,r3,IntervalTimer - _start + _START_OFFSET + li r4,IntervalTimer@l mtspr IVOR11,r4 /* 11: Interval timer */ - addi r4,r3,WatchdogTimer - _start + _START_OFFSET + li r4,WatchdogTimer@l mtspr IVOR12,r4 /* 12: Watchdog timer */ - addi r4,r3,DataTLBError - _start + _START_OFFSET + li r4,DataTLBError@l mtspr IVOR13,r4 /* 13: Data TLB error */ - addi r4,r3,InstructionTLBError - _start + _START_OFFSET + li r4,InstructionTLBError@l mtspr IVOR14,r4 /* 14: Instruction TLB error */ - addi r4,r3,DebugBreakpoint - _start + _START_OFFSET + li r4,DebugBreakpoint@l mtspr IVOR15,r4 /* 15: Debug */ #endif
@@ -1121,7 +1118,7 @@ switch_as: /*--------------------------------------------------------------*/ lis r3,CONFIG_SYS_MONITOR_BASE@h ori r3,r3,CONFIG_SYS_MONITOR_BASE@l - addi r3,r3,_start_cont - _start + _START_OFFSET + addi r3,r3,_start_cont - _start mtlr r3 blr #endif @@ -1165,7 +1162,6 @@ _start_cont: /* NOTREACHED - board_init_f() does not return */
#ifndef MINIMAL_SPL - . = EXC_OFF_SYS_RESET .globl _start_of_vectors _start_of_vectors:
@@ -1185,7 +1181,6 @@ _start_of_vectors: STD_EXCEPTION(0x0500, ExtInterrupt, ExtIntException)
/* Alignment exception. */ - . = 0x0600 Alignment: EXCEPTION_PROLOG(SRR0, SRR1) mfspr r4,DAR @@ -1193,21 +1188,20 @@ Alignment: mfspr r5,DSISR stw r5,_DSISR(r21) addi r3,r1,STACK_FRAME_OVERHEAD - EXC_XFER_TEMPLATE(Alignment, AlignmentException, MSR_KERNEL, COPY_EE) + EXC_XFER_TEMPLATE(0x600, Alignment, AlignmentException, + MSR_KERNEL, COPY_EE)
/* Program check exception */ - . = 0x0700 ProgramCheck: EXCEPTION_PROLOG(SRR0, SRR1) addi r3,r1,STACK_FRAME_OVERHEAD - EXC_XFER_TEMPLATE(ProgramCheck, ProgramCheckException, + EXC_XFER_TEMPLATE(0x700, ProgramCheck, ProgramCheckException, MSR_KERNEL, COPY_EE)
/* No FPU on MPC85xx. This exception is not supposed to happen. */ STD_EXCEPTION(0x0800, FPUnavailable, UnknownException)
- . = 0x0900 /* * r0 - SYSCALL number * r3-... arguments @@ -1293,32 +1287,22 @@ _end_of_vectors: * This code finishes saving the registers to the exception frame * and jumps to the appropriate handler for the exception. * Register r21 is pointer into trap frame, r1 has new stack pointer. + * r23 is the address of the handler. */ .globl transfer_to_handler transfer_to_handler: - stw r22,_NIP(r21) - lis r22,MSR_POW@h - andc r23,r23,r22 - stw r23,_MSR(r21) SAVE_GPR(7, r21) SAVE_4GPRS(8, r21) SAVE_8GPRS(12, r21) SAVE_8GPRS(24, r21)
- mflr r23 - andi. r24,r23,0x3f00 /* get vector offset */ - stw r24,TRAP(r21) li r22,0 stw r22,RESULT(r21) mtspr SPRG2,r22 /* r1 is now kernel sp */
- lwz r24,0(r23) /* virtual address of handler */ - lwz r23,4(r23) /* where to go when done */ - mtspr SRR0,r24 - mtspr SRR1,r20 - mtlr r23 - SYNC - rfi /* jump to handler, enable MMU */ + mtctr r23 /* virtual address of handler */ + mtmsr r20 + bctrl
int_return: mfmsr r28 /* Disable interrupts */ @@ -1728,7 +1712,7 @@ relocate_code: * initialization, now running from RAM. */
- addi r0,r10,in_ram - _start + _START_OFFSET + addi r0,r10,in_ram - _start
/* * As IVPR is going to point RAM address, @@ -1816,89 +1800,41 @@ clear_bss: */ .globl trap_init trap_init: - mflr r4 /* save link register */ - GET_GOT - lwz r7,GOT(_start_of_vectors) - lwz r8,GOT(_end_of_vectors) - - li r9,0x100 /* reset vector always at 0x100 */ - - cmplw 0,r7,r8 - bgelr /* return if r7>=r8 - just in case */ -1: - lwz r0,0(r7) - stw r0,0(r9) - addi r7,r7,4 - addi r9,r9,4 - cmplw 0,r7,r8 - bne 1b + /* Update IVORs as per relocation */ + mtspr IVPR,r3
- /* - * relocate `hdlr' and `int_return' entries - */ - li r7,.L_CriticalInput - _start + _START_OFFSET - bl trap_reloc - li r7,.L_MachineCheck - _start + _START_OFFSET - bl trap_reloc - li r7,.L_DataStorage - _start + _START_OFFSET - bl trap_reloc - li r7,.L_InstStorage - _start + _START_OFFSET - bl trap_reloc - li r7,.L_ExtInterrupt - _start + _START_OFFSET - bl trap_reloc - li r7,.L_Alignment - _start + _START_OFFSET - bl trap_reloc - li r7,.L_ProgramCheck - _start + _START_OFFSET - bl trap_reloc - li r7,.L_FPUnavailable - _start + _START_OFFSET - bl trap_reloc - li r7,.L_Decrementer - _start + _START_OFFSET - bl trap_reloc - li r7,.L_IntervalTimer - _start + _START_OFFSET - li r8,_end_of_vectors - _start + _START_OFFSET -2: - bl trap_reloc - addi r7,r7,0x100 /* next exception vector */ - cmplw 0,r7,r8 - blt 2b - - /* Update IVORs as per relocated vector table address */ - li r7,0x0100 - mtspr IVOR0,r7 /* 0: Critical input */ - li r7,0x0200 - mtspr IVOR1,r7 /* 1: Machine check */ - li r7,0x0300 - mtspr IVOR2,r7 /* 2: Data storage */ - li r7,0x0400 - mtspr IVOR3,r7 /* 3: Instruction storage */ - li r7,0x0500 - mtspr IVOR4,r7 /* 4: External interrupt */ - li r7,0x0600 - mtspr IVOR5,r7 /* 5: Alignment */ - li r7,0x0700 - mtspr IVOR6,r7 /* 6: Program check */ - li r7,0x0800 - mtspr IVOR7,r7 /* 7: floating point unavailable */ - li r7,0x0900 - mtspr IVOR8,r7 /* 8: System call */ + li r4,CriticalInput@l + mtspr IVOR0,r4 /* 0: Critical input */ + li r4,MachineCheck@l + mtspr IVOR1,r4 /* 1: Machine check */ + li r4,DataStorage@l + mtspr IVOR2,r4 /* 2: Data storage */ + li r4,InstStorage@l + mtspr IVOR3,r4 /* 3: Instruction storage */ + li r4,ExtInterrupt@l + mtspr IVOR4,r4 /* 4: External interrupt */ + li r4,Alignment@l + mtspr IVOR5,r4 /* 5: Alignment */ + li r4,ProgramCheck@l + mtspr IVOR6,r4 /* 6: Program check */ + li r4,FPUnavailable@l + mtspr IVOR7,r4 /* 7: floating point unavailable */ + li r4,SystemCall@l + mtspr IVOR8,r4 /* 8: System call */ /* 9: Auxiliary processor unavailable(unsupported) */ - li r7,0x0a00 - mtspr IVOR10,r7 /* 10: Decrementer */ - li r7,0x0b00 - mtspr IVOR11,r7 /* 11: Interval timer */ - li r7,0x0c00 - mtspr IVOR12,r7 /* 12: Watchdog timer */ - li r7,0x0d00 - mtspr IVOR13,r7 /* 13: Data TLB error */ - li r7,0x0e00 - mtspr IVOR14,r7 /* 14: Instruction TLB error */ - li r7,0x0f00 - mtspr IVOR15,r7 /* 15: Debug */ - - lis r7,0x0 - mtspr IVPR,r7 - - mtlr r4 /* restore link register */ + li r4,Decrementer@l + mtspr IVOR10,r4 /* 10: Decrementer */ + li r4,IntervalTimer@l + mtspr IVOR11,r4 /* 11: Interval timer */ + li r4,WatchdogTimer@l + mtspr IVOR12,r4 /* 12: Watchdog timer */ + li r4,DataTLBError@l + mtspr IVOR13,r4 /* 13: Data TLB error */ + li r4,InstructionTLBError@l + mtspr IVOR14,r4 /* 14: Instruction TLB error */ + li r4,DebugBreakpoint@l + mtspr IVOR15,r4 /* 15: Debug */ + blr
.globl unlock_ram_in_cache diff --git a/include/mpc85xx.h b/include/mpc85xx.h index 11d8985..3753e47 100644 --- a/include/mpc85xx.h +++ b/include/mpc85xx.h @@ -6,10 +6,6 @@ #ifndef __MPC85xx_H__ #define __MPC85xx_H__
-/* define for common ppc_asm.tmpl */ -#define EXC_OFF_SYS_RESET 0x100 /* System reset */ -#define _START_OFFSET 0 - #if defined(CONFIG_E500) #include <e500.h> #endif diff --git a/include/ppc_asm.tmpl b/include/ppc_asm.tmpl index 36d5975..ba166eb 100644 --- a/include/ppc_asm.tmpl +++ b/include/ppc_asm.tmpl @@ -12,6 +12,8 @@ #ifndef __PPC_ASM_TMPL__ #define __PPC_ASM_TMPL__
+#include <config.h> + /*************************************************************************** * * These definitions simplify the ugly declarations necessary for GOT @@ -243,6 +245,45 @@ */ #define COPY_EE(d, s) rlwimi d,s,0,16,16 #define NOCOPY(d, s) + +#ifdef CONFIG_E500 +#define EXC_XFER_TEMPLATE(n, label, hdlr, msr, copyee) \ + stw r22,_NIP(r21); \ + stw r23,_MSR(r21); \ + li r23,n; \ + stw r23,TRAP(r21); \ + li r20,msr; \ + copyee(r20,r23); \ + rlwimi r20,r23,0,25,25; \ + mtmsr r20; \ + bl 1f; \ +1: mflr r23; \ + addis r23,r23,(hdlr - 1b)@ha; \ + addi r23,r23,(hdlr - 1b)@l; \ + b transfer_to_handler + +#define STD_EXCEPTION(n, label, hdlr) \ +label: \ + EXCEPTION_PROLOG(SRR0, SRR1); \ + addi r3,r1,STACK_FRAME_OVERHEAD; \ + EXC_XFER_TEMPLATE(n, label, hdlr, MSR_KERNEL, NOCOPY) \ + +#define CRIT_EXCEPTION(n, label, hdlr) \ +label: \ + EXCEPTION_PROLOG(CSRR0, CSRR1); \ + addi r3,r1,STACK_FRAME_OVERHEAD; \ + EXC_XFER_TEMPLATE(n, label, hdlr, \ + MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE), NOCOPY) \ + +#define MCK_EXCEPTION(n, label, hdlr) \ +label: \ + EXCEPTION_PROLOG(MCSRR0, MCSRR1); \ + addi r3,r1,STACK_FRAME_OVERHEAD; \ + EXC_XFER_TEMPLATE(n, label, hdlr, \ + MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE), NOCOPY) \ + +#else /* !E500 */ + #define EXC_XFER_TEMPLATE(label, hdlr, msr, copyee) \ bl 1f; \ 1: mflr r20; \ @@ -280,4 +321,5 @@ label: \ EXC_XFER_TEMPLATE(label, hdlr, \ MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE), NOCOPY) \
+#endif /* !E500 */ #endif /* __PPC_ASM_TMPL__ */
U-Boot does not have system calls (the services it exposes to standalone commands use a different mechanism), so the syscall handler is dead code. It's also broken code, as it assumes it is located at 0xc00 -- while even before the patch to stop relocating exception vectors to 0, U-Boot had the syscall at 0x900.
The critical and machine check return paths are never called -- the regular exception return path is used instead, which works because xSRR0/1 have already been saved and can be restored via the regular SRR0/1 (we don't care too much in U-Boot about taking a critical/mcheck inside another exception prolog/epilog).
Also remove a few other small unused functions.
Signed-off-by: Scott Wood scottwood@freescale.com --- arch/powerpc/cpu/mpc85xx/start.S | 138 +-------------------------------------- include/common.h | 1 - 2 files changed, 1 insertion(+), 138 deletions(-)
diff --git a/arch/powerpc/cpu/mpc85xx/start.S b/arch/powerpc/cpu/mpc85xx/start.S index 61883cb..28f04ee 100644 --- a/arch/powerpc/cpu/mpc85xx/start.S +++ b/arch/powerpc/cpu/mpc85xx/start.S @@ -1201,73 +1201,7 @@ ProgramCheck: /* No FPU on MPC85xx. This exception is not supposed to happen. */ STD_EXCEPTION(0x0800, FPUnavailable, UnknownException) - -/* - * r0 - SYSCALL number - * r3-... arguments - */ -SystemCall: - addis r11,r0,0 /* get functions table addr */ - ori r11,r11,0 /* Note: this code is patched in trap_init */ - addis r12,r0,0 /* get number of functions */ - ori r12,r12,0 - - cmplw 0,r0,r12 - bge 1f - - rlwinm r0,r0,2,0,31 /* fn_addr = fn_tbl[r0] */ - add r11,r11,r0 - lwz r11,0(r11) - - li r20,0xd00-4 /* Get stack pointer */ - lwz r12,0(r20) - subi r12,r12,12 /* Adjust stack pointer */ - li r0,0xc00+_end_back-SystemCall - cmplw 0,r0,r12 /* Check stack overflow */ - bgt 1f - stw r12,0(r20) - - mflr r0 - stw r0,0(r12) - mfspr r0,SRR0 - stw r0,4(r12) - mfspr r0,SRR1 - stw r0,8(r12) - - li r12,0xc00+_back-SystemCall - mtlr r12 - mtspr SRR0,r11 - -1: SYNC - rfi -_back: - - mfmsr r11 /* Disable interrupts */ - li r12,0 - ori r12,r12,MSR_EE - andc r11,r11,r12 - SYNC /* Some chip revs need this... */ - mtmsr r11 - SYNC - - li r12,0xd00-4 /* restore regs */ - lwz r12,0(r12) - - lwz r11,0(r12) - mtlr r11 - lwz r11,4(r12) - mtspr SRR0,r11 - lwz r11,8(r12) - mtspr SRR1,r11 - - addi r12,r12,12 /* Adjust stack pointer */ - li r20,0xd00-4 - stw r12,0(r20) - - SYNC - rfi -_end_back: - + STD_EXCEPTION(0x0900, SystemCall, UnknownException) STD_EXCEPTION(0x0a00, Decrementer, timer_interrupt) STD_EXCEPTION(0x0b00, IntervalTimer, UnknownException) STD_EXCEPTION(0x0c00, WatchdogTimer, UnknownException) @@ -1334,66 +1268,6 @@ int_return: SYNC rfi
-crit_return: - mfmsr r28 /* Disable interrupts */ - li r4,0 - ori r4,r4,MSR_EE - andc r28,r28,r4 - SYNC /* Some chip revs need this... */ - mtmsr r28 - SYNC - lwz r2,_CTR(r1) - lwz r0,_LINK(r1) - mtctr r2 - mtlr r0 - lwz r2,_XER(r1) - lwz r0,_CCR(r1) - mtspr XER,r2 - mtcrf 0xFF,r0 - REST_10GPRS(3, r1) - REST_10GPRS(13, r1) - REST_8GPRS(23, r1) - REST_GPR(31, r1) - lwz r2,_NIP(r1) /* Restore environment */ - lwz r0,_MSR(r1) - mtspr SPRN_CSRR0,r2 - mtspr SPRN_CSRR1,r0 - lwz r0,GPR0(r1) - lwz r2,GPR2(r1) - lwz r1,GPR1(r1) - SYNC - rfci - -mck_return: - mfmsr r28 /* Disable interrupts */ - li r4,0 - ori r4,r4,MSR_EE - andc r28,r28,r4 - SYNC /* Some chip revs need this... */ - mtmsr r28 - SYNC - lwz r2,_CTR(r1) - lwz r0,_LINK(r1) - mtctr r2 - mtlr r0 - lwz r2,_XER(r1) - lwz r0,_CCR(r1) - mtspr XER,r2 - mtcrf 0xFF,r0 - REST_10GPRS(3, r1) - REST_10GPRS(13, r1) - REST_8GPRS(23, r1) - REST_GPR(31, r1) - lwz r2,_NIP(r1) /* Restore environment */ - lwz r0,_MSR(r1) - mtspr SPRN_MCSRR0,r2 - mtspr SPRN_MCSRR1,r0 - lwz r0,GPR0(r1) - lwz r2,GPR2(r1) - lwz r1,GPR1(r1) - SYNC - rfmci - /* Cache functions. */ .globl flush_icache @@ -1478,11 +1352,6 @@ dcache_status: andi. r3,r3,L1CSR0_DCE blr
- .globl get_pir -get_pir: - mfspr r3,PIR - blr - .globl get_pvr get_pvr: mfspr r3,PVR @@ -1493,11 +1362,6 @@ get_svr: mfspr r3,SVR blr
- .globl wr_tcr -wr_tcr: - mtspr TCR,r3 - blr - /*------------------------------------------------------------------------------- */ /* Function: in8 */ /* Description: Input 8 bits */ diff --git a/include/common.h b/include/common.h index 6df05b8..f2d0f64 100644 --- a/include/common.h +++ b/include/common.h @@ -471,7 +471,6 @@ int testdram(void); defined(CONFIG_8xx) uint get_immr (uint); #endif -uint get_pir (void); #if defined(CONFIG_MPC5xxx) uint get_svr (void); #endif
On 04/07/2015 06:20 PM, Scott Wood wrote:
U-Boot does not have system calls (the services it exposes to standalone commands use a different mechanism), so the syscall handler is dead code. It's also broken code, as it assumes it is located at 0xc00 -- while even before the patch to stop relocating exception vectors to 0, U-Boot had the syscall at 0x900.
The critical and machine check return paths are never called -- the regular exception return path is used instead, which works because xSRR0/1 have already been saved and can be restored via the regular SRR0/1 (we don't care too much in U-Boot about taking a critical/mcheck inside another exception prolog/epilog).
Also remove a few other small unused functions.
Signed-off-by: Scott Wood scottwood@freescale.com
Applied to mpc85xx master, awaiting upstream.
York
On 04/07/2015 06:20 PM, Scott Wood wrote:
Booke does not require exception vectors to be located at address zero. U-Boot was doing so anyway, simply because that's how it had been done on other PPC. The downside of this is that once the OS is loaded to address zero, the exception vectors have been overwritten -- which makes it difficult to diagnose a crash that happens after that point.
The IVOR setup and trap entry code is simplified somewhat as a result.
Also, there is no longer a need to align individual exceptions on 0x100 byte boundaries.
Signed-off-by: Scott Wood scottwood@freescale.com
Applied to mpc85xx master, awaiting upstream.
York
participants (2)
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Scott Wood -
York Sun