From ab6e570ba33dbee18c2520d386e0f367a9b573c3 Mon Sep 17 00:00:00 2001
From: Paul Mundt <lethal@linux-sh.org>
Date: Thu, 11 Dec 2008 18:46:46 +0900
Subject: sh: Generic kgdb stub support.
This migrates from the old bitrotted kgdb stub implementation and moves
to the generic stub. In the process support for SH-2/SH-2A is also added,
which the old stub never provided.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
---
arch/sh/kernel/kgdb.c | 285 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 285 insertions(+)
create mode 100644 arch/sh/kernel/kgdb.c
(limited to 'arch/sh/kernel/kgdb.c')
diff --git a/arch/sh/kernel/kgdb.c b/arch/sh/kernel/kgdb.c
new file mode 100644
index 000000000000..7c747e7d71b8
--- /dev/null
+++ b/arch/sh/kernel/kgdb.c
@@ -0,0 +1,285 @@
+/*
+ * SuperH KGDB support
+ *
+ * Copyright (C) 2008 Paul Mundt
+ *
+ * Single stepping taken from the old stub by Henry Bell and Jeremy Siegel.
+ *
+ * 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.
+ */
+#include <linux/kgdb.h>
+#include <linux/kdebug.h>
+#include <linux/irq.h>
+#include <linux/io.h>
+#include <asm/cacheflush.h>
+
+char in_nmi = 0; /* Set during NMI to prevent re-entry */
+
+/* Macros for single step instruction identification */
+#define OPCODE_BT(op) (((op) & 0xff00) == 0x8900)
+#define OPCODE_BF(op) (((op) & 0xff00) == 0x8b00)
+#define OPCODE_BTF_DISP(op) (((op) & 0x80) ? (((op) | 0xffffff80) << 1) : \
+ (((op) & 0x7f ) << 1))
+#define OPCODE_BFS(op) (((op) & 0xff00) == 0x8f00)
+#define OPCODE_BTS(op) (((op) & 0xff00) == 0x8d00)
+#define OPCODE_BRA(op) (((op) & 0xf000) == 0xa000)
+#define OPCODE_BRA_DISP(op) (((op) & 0x800) ? (((op) | 0xfffff800) << 1) : \
+ (((op) & 0x7ff) << 1))
+#define OPCODE_BRAF(op) (((op) & 0xf0ff) == 0x0023)
+#define OPCODE_BRAF_REG(op) (((op) & 0x0f00) >> 8)
+#define OPCODE_BSR(op) (((op) & 0xf000) == 0xb000)
+#define OPCODE_BSR_DISP(op) (((op) & 0x800) ? (((op) | 0xfffff800) << 1) : \
+ (((op) & 0x7ff) << 1))
+#define OPCODE_BSRF(op) (((op) & 0xf0ff) == 0x0003)
+#define OPCODE_BSRF_REG(op) (((op) >> 8) & 0xf)
+#define OPCODE_JMP(op) (((op) & 0xf0ff) == 0x402b)
+#define OPCODE_JMP_REG(op) (((op) >> 8) & 0xf)
+#define OPCODE_JSR(op) (((op) & 0xf0ff) == 0x400b)
+#define OPCODE_JSR_REG(op) (((op) >> 8) & 0xf)
+#define OPCODE_RTS(op) ((op) == 0xb)
+#define OPCODE_RTE(op) ((op) == 0x2b)
+
+#define SR_T_BIT_MASK 0x1
+#define STEP_OPCODE 0xc33d
+
+/* Calculate the new address for after a step */
+static short *get_step_address(struct pt_regs *linux_regs)
+{
+ opcode_t op = __raw_readw(linux_regs->pc);
+ long addr;
+
+ /* BT */
+ if (OPCODE_BT(op)) {
+ if (linux_regs->sr & SR_T_BIT_MASK)
+ addr = linux_regs->pc + 4 + OPCODE_BTF_DISP(op);
+ else
+ addr = linux_regs->pc + 2;
+ }
+
+ /* BTS */
+ else if (OPCODE_BTS(op)) {
+ if (linux_regs->sr & SR_T_BIT_MASK)
+ addr = linux_regs->pc + 4 + OPCODE_BTF_DISP(op);
+ else
+ addr = linux_regs->pc + 4; /* Not in delay slot */
+ }
+
+ /* BF */
+ else if (OPCODE_BF(op)) {
+ if (!(linux_regs->sr & SR_T_BIT_MASK))
+ addr = linux_regs->pc + 4 + OPCODE_BTF_DISP(op);
+ else
+ addr = linux_regs->pc + 2;
+ }
+
+ /* BFS */
+ else if (OPCODE_BFS(op)) {
+ if (!(linux_regs->sr & SR_T_BIT_MASK))
+ addr = linux_regs->pc + 4 + OPCODE_BTF_DISP(op);
+ else
+ addr = linux_regs->pc + 4; /* Not in delay slot */
+ }
+
+ /* BRA */
+ else if (OPCODE_BRA(op))
+ addr = linux_regs->pc + 4 + OPCODE_BRA_DISP(op);
+
+ /* BRAF */
+ else if (OPCODE_BRAF(op))
+ addr = linux_regs->pc + 4
+ + linux_regs->regs[OPCODE_BRAF_REG(op)];
+
+ /* BSR */
+ else if (OPCODE_BSR(op))
+ addr = linux_regs->pc + 4 + OPCODE_BSR_DISP(op);
+
+ /* BSRF */
+ else if (OPCODE_BSRF(op))
+ addr = linux_regs->pc + 4
+ + linux_regs->regs[OPCODE_BSRF_REG(op)];
+
+ /* JMP */
+ else if (OPCODE_JMP(op))
+ addr = linux_regs->regs[OPCODE_JMP_REG(op)];
+
+ /* JSR */
+ else if (OPCODE_JSR(op))
+ addr = linux_regs->regs[OPCODE_JSR_REG(op)];
+
+ /* RTS */
+ else if (OPCODE_RTS(op))
+ addr = linux_regs->pr;
+
+ /* RTE */
+ else if (OPCODE_RTE(op))
+ addr = linux_regs->regs[15];
+
+ /* Other */
+ else
+ addr = linux_regs->pc + instruction_size(op);
+
+ flush_icache_range(addr, addr + instruction_size(op));
+ return (short *)addr;
+}
+
+/*
+ * Replace the instruction immediately after the current instruction
+ * (i.e. next in the expected flow of control) with a trap instruction,
+ * so that returning will cause only a single instruction to be executed.
+ * Note that this model is slightly broken for instructions with delay
+ * slots (e.g. B[TF]S, BSR, BRA etc), where both the branch and the
+ * instruction in the delay slot will be executed.
+ */
+
+static unsigned long stepped_address;
+static opcode_t stepped_opcode;
+
+static void do_single_step(struct pt_regs *linux_regs)
+{
+ /* Determine where the target instruction will send us to */
+ unsigned short *addr = get_step_address(linux_regs);
+
+ stepped_address = (int)addr;
+
+ /* Replace it */
+ stepped_opcode = __raw_readw((long)addr);
+ *addr = STEP_OPCODE;
+
+ /* Flush and return */
+ flush_icache_range((long)addr, (long)addr +
+ instruction_size(stepped_opcode));
+}
+
+/* Undo a single step */
+static void undo_single_step(struct pt_regs *linux_regs)
+{
+ /* If we have stepped, put back the old instruction */
+ /* Use stepped_address in case we stopped elsewhere */
+ if (stepped_opcode != 0) {
+ __raw_writew(stepped_opcode, stepped_address);
+ flush_icache_range(stepped_address, stepped_address + 2);
+ }
+
+ stepped_opcode = 0;
+}
+
+void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
+{
+ int i;
+
+ for (i = 0; i < 16; i++)
+ gdb_regs[GDB_R0 + i] = regs->regs[i];
+
+ gdb_regs[GDB_PC] = regs->pc;
+ gdb_regs[GDB_PR] = regs->pr;
+ gdb_regs[GDB_SR] = regs->sr;
+ gdb_regs[GDB_GBR] = regs->gbr;
+ gdb_regs[GDB_MACH] = regs->mach;
+ gdb_regs[GDB_MACL] = regs->macl;
+
+ __asm__ __volatile__ ("stc vbr, %0" : "=r" (gdb_regs[GDB_VBR]));
+}
+
+void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
+{
+ int i;
+
+ for (i = 0; i < 16; i++)
+ regs->regs[GDB_R0 + i] = gdb_regs[GDB_R0 + i];
+
+ regs->pc = gdb_regs[GDB_PC];
+ regs->pr = gdb_regs[GDB_PR];
+ regs->sr = gdb_regs[GDB_SR];
+ regs->gbr = gdb_regs[GDB_GBR];
+ regs->mach = gdb_regs[GDB_MACH];
+ regs->macl = gdb_regs[GDB_MACL];
+
+ __asm__ __volatile__ ("ldc %0, vbr" : : "r" (gdb_regs[GDB_VBR]));
+}
+
+void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
+{
+ gdb_regs[GDB_R15] = p->thread.sp;
+ gdb_regs[GDB_PC] = p->thread.pc;
+}
+
+int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
+ char *remcomInBuffer, char *remcomOutBuffer,
+ struct pt_regs *linux_regs)
+{
+ unsigned long addr;
+ char *ptr;
+
+ /* Undo any stepping we may have done */
+ undo_single_step(linux_regs);
+
+ switch (remcomInBuffer[0]) {
+ case 'c':
+ case 's':
+ /* try to read optional parameter, pc unchanged if no parm */
+ ptr = &remcomInBuffer[1];
+ if (kgdb_hex2long(&ptr, &addr))
+ linux_regs->pc = addr;
+ case 'D':
+ case 'k':
+ atomic_set(&kgdb_cpu_doing_single_step, -1);
+
+ if (remcomInBuffer[0] == 's') {
+ do_single_step(linux_regs);
+ kgdb_single_step = 1;
+
+ atomic_set(&kgdb_cpu_doing_single_step,
+ raw_smp_processor_id());
+ }
+
+ return 0;
+ }
+
+ /* this means that we do not want to exit from the handler: */
+ return -1;
+}
+
+/*
+ * The primary entry points for the kgdb debug trap table entries.
+ */
+BUILD_TRAP_HANDLER(singlestep)
+{
+ unsigned long flags;
+ TRAP_HANDLER_DECL;
+
+ local_irq_save(flags);
+ regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
+ kgdb_handle_exception(vec >> 2, SIGTRAP, 0, regs);
+ local_irq_restore(flags);
+}
+
+
+BUILD_TRAP_HANDLER(breakpoint)
+{
+ unsigned long flags;
+ TRAP_HANDLER_DECL;
+
+ local_irq_save(flags);
+ kgdb_handle_exception(vec >> 2, SIGTRAP, 0, regs);
+ local_irq_restore(flags);
+}
+
+int kgdb_arch_init(void)
+{
+ return 0;
+}
+
+void kgdb_arch_exit(void)
+{
+}
+
+struct kgdb_arch arch_kgdb_ops = {
+ /* Breakpoint instruction: trapa #0x3c */
+#ifdef CONFIG_CPU_LITTLE_ENDIAN
+ .gdb_bpt_instr = { 0x3c, 0xc3 },
+#else
+ .gdb_bpt_instr = { 0xc3, 0x3c },
+#endif
+};
--
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