On Sunday, 25 September 2016 20:05:31 BST Daniel Schwierzeck wrote:
Add exception handlers for generic and EJTAG exceptions. Most of the assembly code is imported from Linux kernel and adapted to U-Boot. The exception vector table will be reserved above the stack before U-Boot is relocated. The exception handlers will be installed and activated after relocation in the initr_traps hook function.
Hi Daniel,
This series looks good :) Just a couple of comments below.
Generic exceptions are handled by showing a CPU register dump similar to Linux kernel. For example:
malta # md 1 00000001: Ooops: $ 0 : 00000000 00000000 00000009 00000004 $ 4 : 8ff7e108 00000000 0000003a 00000000 $ 8 : 00000008 00000001 8ff7cd18 00000004 $12 : 00000002 00000000 00000005 0000003a $16 : 00000004 00000040 00000001 00000001 $20 : 00000000 8fff53c0 00000008 00000004 $24 : ffffffff 8ffdea44 $28 : 90001650 8ff7cd00 00000004 8ffe6818 Hi : 00000000 Lo : 00000004 epc : 8ffe6848 (text bfc28848) ra : 8ffe6818 (text bfc28818) Status: 00000006 Cause : 00000410 (ExcCode 04) BadVA : 8ff9e928 PrId : 00019300 ### ERROR ### Please RESET the board ###
Something I've had in the U-Boot source we use on Boston, Malta & SEAD-3 boards internally for a while is the ability to longjmp back to the shell after an exception. It seems to work pretty well & generally means exceptions are non-fatal. I'll submit that once this goes in.
EJTAG exceptions are checked for SDBBP and delegated to the SDBBP handler if necessary. Otherwise the debug mode will simply be exited. The SDBBP handler currently prints the contents of registers c0_depc and c0_debug. This could be extended in the future to handle semi-hosting according to the MIPS UHI specification.
Signed-off-by: Daniel Schwierzeck daniel.schwierzeck@gmail.com
arch/mips/include/asm/u-boot-mips.h | 4 + arch/mips/lib/Makefile | 2 + arch/mips/lib/genex.S | 214 ++++++++++++++++++++++++++++++++++++ arch/mips/lib/traps.c | 104 ++++++++++++++++++ 4 files changed, 324 insertions(+) create mode 100644 arch/mips/lib/genex.S create mode 100644 arch/mips/lib/traps.c
diff --git a/arch/mips/include/asm/u-boot-mips.h b/arch/mips/include/asm/u-boot-mips.h index 1f527bb..71ff41d 100644 --- a/arch/mips/include/asm/u-boot-mips.h +++ b/arch/mips/include/asm/u-boot-mips.h @@ -5,4 +5,8 @@ #ifndef _U_BOOT_MIPS_H_ #define _U_BOOT_MIPS_H_
+void exc_handler(void); +void except_vec3_generic(void); +void except_vec_ejtag_debug(void);
#endif /* _U_BOOT_MIPS_H_ */ diff --git a/arch/mips/lib/Makefile b/arch/mips/lib/Makefile index 02607f7..659c6ad 100644 --- a/arch/mips/lib/Makefile +++ b/arch/mips/lib/Makefile @@ -7,7 +7,9 @@
obj-y += cache.o obj-y += cache_init.o +obj-y += genex.o obj-y += stack.o +obj-y += traps.o
obj-$(CONFIG_CMD_BOOTM) += bootm.o
diff --git a/arch/mips/lib/genex.S b/arch/mips/lib/genex.S new file mode 100644 index 0000000..f72545d --- /dev/null +++ b/arch/mips/lib/genex.S @@ -0,0 +1,214 @@ +/*
- Copyright (C) 1994 - 2000, 2001, 2003 Ralf Baechle
- Copyright (C) 1999, 2000 Silicon Graphics, Inc.
- Copyright (C) 2002, 2007 Maciej W. Rozycki
- Copyright (C) 2001, 2012 MIPS Technologies, Inc. All rights reserved.
- SPDX-License-Identifier: GPL-2.0+
- */
+#include <asm/asm.h> +#include <asm/regdef.h> +#include <asm/mipsregs.h> +#include <asm/asm-offsets.h>
- .set noreorder
- /*
* Macros copied and adapted from Linux MIPS*/- .macro SAVE_AT
- .set push
- .set noat
- LONG_S $1, PT_R1(sp)
- .set pop
- .endm
- .macro RESTORE_AT
- .set push
- .set noat
- LONG_L $1, PT_R1(sp)
- .set pop
- .endm
- .macro SAVE_TEMP
- mfhi v1
+#ifdef CONFIG_32BIT
- LONG_S $8, PT_R8(sp)
- LONG_S $9, PT_R9(sp)
+#endif
- LONG_S $10, PT_R10(sp)
- LONG_S $11, PT_R11(sp)