[PATCH 0/2] MIPS: import exception stuff from linux kernel

[PATCH 0/2] MIPS: import exception stuff from linux kernel

[Antony Pavlov]

This patch series imports registers saving code from linux kernel.
Just now it makes possible to dump registers state on exception;
this dump is very valuable for debugging purposes.

[PATCH 1/2] MIPS: add asm-offsets.h generation
[PATCH 2/2] MIPS: import exception registers saving from linux kernel

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[PATCH 1/2] MIPS: add asm-offsets.h generation

[Antony Pavlov]

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
---
 arch/mips/Makefile                  | 43 ++++++++++++++++++++++++++
 arch/mips/include/asm/asm-offsets.h |  1 +
 arch/mips/include/asm/ptrace.h      | 35 +++++++++++++++++++++
 arch/mips/lib/asm-offsets.c         | 61 +++++++++++++++++++++++++++++++++++++
 include/linux/kbuild.h              | 15 +++++++++
 5 files changed, 155 insertions(+)
 create mode 100644 arch/mips/include/asm/asm-offsets.h
 create mode 100644 arch/mips/include/asm/ptrace.h
 create mode 100644 arch/mips/lib/asm-offsets.c
 create mode 100644 include/linux/kbuild.h

diff --git a/arch/mips/Makefile b/arch/mips/Makefile
index dc0fe56..62e1acf 100644
--- a/arch/mips/Makefile
+++ b/arch/mips/Makefile
@@ -143,3 +143,46 @@ dtbs: scripts
 KBUILD_DTBS := dtbs
 
 KBUILD_IMAGE ?= $(KBUILD_BINARY)
+
+#####
+# Generate asm-offsets.h
+#
+
+offsets-file := include/generated/asm-offsets.h
+
+always  += $(offsets-file)
+targets += $(offsets-file)
+targets += arch/$(SRCARCH)/lib/asm-offsets.s
+
+# Default sed regexp - multiline due to syntax constraints
+define sed-y
+	"/^->/{s:->#\(.*\):/* \1 */:; \
+	s:^->\([^ ]*\) [\$$#]*\([-0-9]*\) \(.*\):#define \1 \2 /* \3 */:; \
+	s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \
+	s:->::; p;}"
+endef
+
+quiet_cmd_offsets = GEN     $@
+define cmd_offsets
+	(set -e; \
+	 echo "#ifndef __ASM_OFFSETS_H__"; \
+	 echo "#define __ASM_OFFSETS_H__"; \
+	 echo "/*"; \
+	 echo " * DO NOT MODIFY."; \
+	 echo " *"; \
+	 echo " * This file was generated by Kbuild"; \
+	 echo " *"; \
+	 echo " */"; \
+	 echo ""; \
+	 sed -ne $(sed-y) $<; \
+	 echo ""; \
+	 echo "#endif" ) > $@
+endef
+
+# We use internal kbuild rules to avoid the "is up to date" message from make
+arch/$(SRCARCH)/lib/asm-offsets.s: arch/$(SRCARCH)/lib/asm-offsets.c FORCE
+	$(Q)mkdir -p $(dir $@)
+	$(call if_changed_dep,cc_s_c)
+
+$(obj)/$(offsets-file): arch/$(SRCARCH)/lib/asm-offsets.s Makefile
+	$(call cmd,offsets)
diff --git a/arch/mips/include/asm/asm-offsets.h b/arch/mips/include/asm/asm-offsets.h
new file mode 100644
index 0000000..d370ee3
--- /dev/null
+++ b/arch/mips/include/asm/asm-offsets.h
@@ -0,0 +1 @@
+#include <generated/asm-offsets.h>
diff --git a/arch/mips/include/asm/ptrace.h b/arch/mips/include/asm/ptrace.h
new file mode 100644
index 0000000..211834d
--- /dev/null
+++ b/arch/mips/include/asm/ptrace.h
@@ -0,0 +1,35 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 1994, 95, 96, 97, 98, 99, 2000 by Ralf Baechle
+ * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
+ */
+
+#ifndef _ASM_PTRACE_H
+#define _ASM_PTRACE_H
+
+/*
+ * This struct defines the way the registers are stored on the stack during an
+ * exception. As usual the registers k0/k1 aren't being saved.
+ */
+struct pt_regs {
+#ifdef CONFIG_32BIT
+	/* Pad bytes for argument save space on the stack. */
+	unsigned long pad0[6];
+#endif
+
+	/* Saved main processor registers. */
+	unsigned long regs[32];
+
+	/* Saved special registers. */
+	unsigned long cp0_status;
+	unsigned long hi;
+	unsigned long lo;
+	unsigned long cp0_badvaddr;
+	unsigned long cp0_cause;
+	unsigned long cp0_epc;
+} __attribute__ ((aligned (8)));
+
+#endif /* _ASM_PTRACE_H */
diff --git a/arch/mips/lib/asm-offsets.c b/arch/mips/lib/asm-offsets.c
new file mode 100644
index 0000000..457bc8a
--- /dev/null
+++ b/arch/mips/lib/asm-offsets.c
@@ -0,0 +1,61 @@
+/*
+ * offset.c: Calculate pt_regs and task_struct offsets.
+ *
+ * Copyright (C) 1996 David S. Miller
+ * Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003 Ralf Baechle
+ * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
+ *
+ * Kevin Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
+ * Copyright (C) 2000 MIPS Technologies, Inc.
+ */
+
+#include <linux/kbuild.h>
+#include <linux/stddef.h>
+#include <asm/ptrace.h>
+
+void output_ptreg_defines(void);
+
+void output_ptreg_defines(void)
+{
+	COMMENT("MIPS pt_regs offsets.");
+	OFFSET(PT_R0, pt_regs, regs[0]);
+	OFFSET(PT_R1, pt_regs, regs[1]);
+	OFFSET(PT_R2, pt_regs, regs[2]);
+	OFFSET(PT_R3, pt_regs, regs[3]);
+	OFFSET(PT_R4, pt_regs, regs[4]);
+	OFFSET(PT_R5, pt_regs, regs[5]);
+	OFFSET(PT_R6, pt_regs, regs[6]);
+	OFFSET(PT_R7, pt_regs, regs[7]);
+	OFFSET(PT_R8, pt_regs, regs[8]);
+	OFFSET(PT_R9, pt_regs, regs[9]);
+	OFFSET(PT_R10, pt_regs, regs[10]);
+	OFFSET(PT_R11, pt_regs, regs[11]);
+	OFFSET(PT_R12, pt_regs, regs[12]);
+	OFFSET(PT_R13, pt_regs, regs[13]);
+	OFFSET(PT_R14, pt_regs, regs[14]);
+	OFFSET(PT_R15, pt_regs, regs[15]);
+	OFFSET(PT_R16, pt_regs, regs[16]);
+	OFFSET(PT_R17, pt_regs, regs[17]);
+	OFFSET(PT_R18, pt_regs, regs[18]);
+	OFFSET(PT_R19, pt_regs, regs[19]);
+	OFFSET(PT_R20, pt_regs, regs[20]);
+	OFFSET(PT_R21, pt_regs, regs[21]);
+	OFFSET(PT_R22, pt_regs, regs[22]);
+	OFFSET(PT_R23, pt_regs, regs[23]);
+	OFFSET(PT_R24, pt_regs, regs[24]);
+	OFFSET(PT_R25, pt_regs, regs[25]);
+	OFFSET(PT_R26, pt_regs, regs[26]);
+	OFFSET(PT_R27, pt_regs, regs[27]);
+	OFFSET(PT_R28, pt_regs, regs[28]);
+	OFFSET(PT_R29, pt_regs, regs[29]);
+	OFFSET(PT_R30, pt_regs, regs[30]);
+	OFFSET(PT_R31, pt_regs, regs[31]);
+	OFFSET(PT_LO, pt_regs, lo);
+	OFFSET(PT_HI, pt_regs, hi);
+	OFFSET(PT_EPC, pt_regs, cp0_epc);
+	OFFSET(PT_BVADDR, pt_regs, cp0_badvaddr);
+	OFFSET(PT_STATUS, pt_regs, cp0_status);
+	OFFSET(PT_CAUSE, pt_regs, cp0_cause);
+	DEFINE(PT_SIZE, sizeof(struct pt_regs));
+	BLANK();
+}
diff --git a/include/linux/kbuild.h b/include/linux/kbuild.h
new file mode 100644
index 0000000..359d4a8
--- /dev/null
+++ b/include/linux/kbuild.h
@@ -0,0 +1,15 @@
+#ifndef __LINUX_KBUILD_H
+#define __LINUX_KBUILD_H
+
+#define DEFINE(sym, val) \
+	asm volatile("\n->" #sym " %0 " #val : : "i" (val))
+
+#define BLANK() asm volatile("\n->" : : )
+
+#define OFFSET(sym, str, mem) \
+	DEFINE(sym, offsetof(struct str, mem))
+
+#define COMMENT(x) \
+	asm volatile("\n->#" x)
+
+#endif
-- 
1.8.4.4


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[PATCH 2/2] MIPS: import exception registers saving from linux kernel

[Antony Pavlov]

Checking registers saving:

    $ make qemu-malta_defconfig
    $ make

    ...

    $ qemu-system-mips -nodefaults -M malta -m 256 \
       -nographic -serial stdio -bios ./barebox-flash-image

    ...

    barebox:/ md -l 0x03

    Ooops, address error on load or ifetch!

    $ 0   : 00000000 00000000 ffffffff 0000003f
    $ 4   : 00000000 ffffffff 00000004 00000004
    $ 8   : 00000003 a0404d50 00000001 00000002
    $12   : a0404d50 0000000a a0840000 00000003
    $16   : 00000100 a0404d50 00000100 00000003
    $20   : 00000000 a0406cd8 00000000 00000000
    $24   : a083b4d8 a083058c
    $28   : 00000000 a03ffca8 a0406ab0 a0830604
    Hi    : 00000000
    Lo    : 00000040
    epc   : a083056c
    ra    : a0830604
    Status: 00000006
    Cause : 00000410
    Config: 80008482

    ### ERROR ### Please RESET the board ###

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
---
 arch/mips/include/asm/stackframe.h | 105 +++++++++++++++++++++++++++++++++++++
 arch/mips/lib/genex.S              |   2 +
 arch/mips/lib/traps.c              |  46 +++++++++++++---
 3 files changed, 146 insertions(+), 7 deletions(-)
 create mode 100644 arch/mips/include/asm/stackframe.h

diff --git a/arch/mips/include/asm/stackframe.h b/arch/mips/include/asm/stackframe.h
new file mode 100644
index 0000000..0266ec6
--- /dev/null
+++ b/arch/mips/include/asm/stackframe.h
@@ -0,0 +1,105 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 1994, 95, 96, 99, 2001 Ralf Baechle
+ * Copyright (C) 1994, 1995, 1996 Paul M. Antoine.
+ * Copyright (C) 1999 Silicon Graphics, Inc.
+ * Copyright (C) 2007  Maciej W. Rozycki
+ */
+#ifndef _ASM_STACKFRAME_H
+#define _ASM_STACKFRAME_H
+
+#include <asm/asm.h>
+#include <asm/mipsregs.h>
+#include <asm/asm-offsets.h>
+
+		.macro	SAVE_AT
+		.set	push
+		.set	noat
+		LONG_S	$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)
+		LONG_S	$12, PT_R12(sp)
+
+		LONG_S	v1, PT_HI(sp)
+		mflo	v1
+
+		LONG_S	$13, PT_R13(sp)
+		LONG_S	$14, PT_R14(sp)
+		LONG_S	$15, PT_R15(sp)
+		LONG_S	$24, PT_R24(sp)
+
+		LONG_S	v1, PT_LO(sp)
+
+		.endm
+
+		.macro	SAVE_STATIC
+		LONG_S	$16, PT_R16(sp)
+		LONG_S	$17, PT_R17(sp)
+		LONG_S	$18, PT_R18(sp)
+		LONG_S	$19, PT_R19(sp)
+		LONG_S	$20, PT_R20(sp)
+		LONG_S	$21, PT_R21(sp)
+		LONG_S	$22, PT_R22(sp)
+		LONG_S	$23, PT_R23(sp)
+		LONG_S	$30, PT_R30(sp)
+		.endm
+
+		.macro	SAVE_SOME
+		.set	push
+		.set	noat
+		.set	reorder
+		.set	at=k0
+		move	k1, sp
+		PTR_SUBU k1, PT_SIZE
+		.set	noat
+		move	k0, sp
+		move	sp, k1
+		LONG_S	k0, PT_R29(sp)
+		LONG_S	$3, PT_R3(sp)
+		/*
+		 * You might think that you don't need to save $0,
+		 * but the FPU emulator and gdb remote debug stub
+		 * need it to operate correctly
+		 */
+		LONG_S	$0, PT_R0(sp)
+		mfc0	v1, CP0_STATUS
+		LONG_S	$2, PT_R2(sp)
+		LONG_S	v1, PT_STATUS(sp)
+		LONG_S	$4, PT_R4(sp)
+		mfc0	v1, CP0_CAUSE
+		LONG_S	$5, PT_R5(sp)
+		LONG_S	v1, PT_CAUSE(sp)
+		LONG_S	$6, PT_R6(sp)
+		MFC0	v1, CP0_EPC
+		LONG_S	$7, PT_R7(sp)
+#ifdef CONFIG_64BIT
+		LONG_S	$8, PT_R8(sp)
+		LONG_S	$9, PT_R9(sp)
+#endif
+		LONG_S	v1, PT_EPC(sp)
+		LONG_S	$25, PT_R25(sp)
+		LONG_S	$28, PT_R28(sp)
+		LONG_S	$31, PT_R31(sp)
+		.set	pop
+		.endm
+
+		.macro	SAVE_ALL
+		SAVE_SOME
+		SAVE_AT
+		SAVE_TEMP
+		SAVE_STATIC
+		.endm
+
+#endif /* _ASM_STACKFRAME_H */
diff --git a/arch/mips/lib/genex.S b/arch/mips/lib/genex.S
index d6f65a2..8941714 100644
--- a/arch/mips/lib/genex.S
+++ b/arch/mips/lib/genex.S
@@ -1,6 +1,7 @@
 #include <asm/asm.h>
 #include <asm/regdef.h>
 #include <asm/mipsregs.h>
+#include <asm/stackframe.h>
 
 	.text
 	.set	macro
@@ -10,6 +11,7 @@
 
 /* Exception vector */
 NESTED(handle_reserved, 0, sp)
+	SAVE_ALL
 	la	k0, barebox_exc_handler
 	jal	k0
 	 move	a0, sp
diff --git a/arch/mips/lib/traps.c b/arch/mips/lib/traps.c
index 4e167cc..0a5914e 100644
--- a/arch/mips/lib/traps.c
+++ b/arch/mips/lib/traps.c
@@ -1,8 +1,9 @@
 #include <common.h>
 
 #include <asm/mipsregs.h>
+#include <asm/ptrace.h>
 
-void barebox_exc_handler(void *regs);
+void barebox_exc_handler(const struct pt_regs *regs);
 
 /*
  * Trap codes from OpenBSD trap.h
@@ -95,13 +96,44 @@ static char *get_exc_name(u32 cause)
 	return "unknown exception";
 }
 
-void barebox_exc_handler(void *regs)
+void barebox_exc_handler(const struct pt_regs *regs)
 {
-	printf("\nOoops, %s!\n", get_exc_name(read_c0_cause()));
-	printf("EPC = 0x%08x\n", read_c0_epc());
-	printf("CP0_STATUS = 0x%08x\n", read_c0_status());
-	printf("CP0_CAUSE = 0x%08x\n", read_c0_cause());
-	printf("CP0_CONFIG = 0x%08x\n\n", read_c0_config());
+	const int field = 2 * sizeof(unsigned long);
+	unsigned int cause = regs->cp0_cause;
+	int i;
+
+	printf("\nOoops, %s!\n\n", get_exc_name(cause));
+
+	/*
+	 * Saved main processor registers
+	 */
+	for (i = 0; i < 32; ) {
+		if ((i % 4) == 0)
+			printf("$%2d   :", i);
+		if (i == 0)
+			printf(" %0*lx", field, 0UL);
+		else if (i == 26 || i == 27)
+			printf(" %*s", field, "");
+		else
+			printf(" %0*lx", field, regs->regs[i]);
+
+		i++;
+		if ((i % 4) == 0)
+			printf("\n");
+	}
+
+	printf("Hi    : %0*lx\n", field, regs->hi);
+	printf("Lo    : %0*lx\n", field, regs->lo);
+
+	/*
+	 * Saved cp0 registers
+	 */
+	printf("epc   : %0*lx\n", field, regs->cp0_epc);
+	printf("ra    : %0*lx\n", field, regs->regs[31]);
+
+	printf("Status: %08x\n", (uint32_t) regs->cp0_status);
+	printf("Cause : %08x\n", cause);
+	printf("Config: %08x\n\n", read_c0_config());
 
 	hang();
 }
-- 
1.8.4.4


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Re: [PATCH 0/2] MIPS: import exception stuff from linux kernel

[Sascha Hauer]

On Wed, Dec 04, 2013 at 12:48:53AM +0400, Antony Pavlov wrote:
> This patch series imports registers saving code from linux kernel.
> Just now it makes possible to dump registers state on exception;
> this dump is very valuable for debugging purposes.
> 
> [PATCH 1/2] MIPS: add asm-offsets.h generation
> [PATCH 2/2] MIPS: import exception registers saving from linux kernel

Applied, thanks

Sascha

> 
> _______________________________________________
> barebox mailing list
> barebox@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/barebox
> 

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