kgdb, powerpc: arch specific powerpc kgdb support

This patch removes the old kgdb reminants from ARCH=powerpc and
implements the new style arch specific stub for the common kgdb core
interface.

It is possible to have xmon and kgdb in the same kernel, but you
cannot use both at the same time because there is only one set of
debug hooks.

The arch specific kgdb implementation saves the previous state of the
debug hooks and restores them if you unconfigure the kgdb I/O driver.
Kgdb should have no impact on a kernel that has no kgdb I/O driver
configured.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>

3 files changed, 411 insertions, 16 deletions

diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index bf0b1fd0ec34..1a4094704b1f 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -74,6 +74,7 @@ obj-y				+= time.o prom.o traps.o setup-common.o \
                                    misc_$(CONFIG_WORD_SIZE).o
 obj-$(CONFIG_PPC32)             += entry_32.o setup_32.o
 obj-$(CONFIG_PPC64)             += dma_64.o iommu.o
+obj-$(CONFIG_KGDB)              += kgdb.o
 obj-$(CONFIG_PPC_MULTIPLATFORM) += prom_init.o
 obj-$(CONFIG_MODULES)           += ppc_ksyms.o
 obj-$(CONFIG_BOOTX_TEXT)        += btext.o
diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c
new file mode 100644
index 000000000000..b4fdf2f2743c
--- /dev/null
+++ b/arch/powerpc/kernel/kgdb.c
@@ -0,0 +1,410 @@
+/*
+ * PowerPC backend to the KGDB stub.
+ *
+ * 1998 (c) Michael AK Tesch (tesch@cs.wisc.edu)
+ * Copyright (C) 2003 Timesys Corporation.
+ * Copyright (C) 2004-2006 MontaVista Software, Inc.
+ * PPC64 Mods (C) 2005 Frank Rowand (frowand@mvista.com)
+ * PPC32 support restored by Vitaly Wool <vwool@ru.mvista.com> and
+ * Sergei Shtylyov <sshtylyov@ru.mvista.com>
+ * Copyright (C) 2007-2008 Wind River Systems, Inc.
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2. This program as licensed "as is" without any warranty of any
+ * kind, whether express or implied.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/kgdb.h>
+#include <linux/smp.h>
+#include <linux/signal.h>
+#include <linux/ptrace.h>
+#include <asm/current.h>
+#include <asm/processor.h>
+#include <asm/machdep.h>
+
+/*
+ * This table contains the mapping between PowerPC hardware trap types, and
+ * signals, which are primarily what GDB understands.  GDB and the kernel
+ * don't always agree on values, so we use constants taken from gdb-6.2.
+ */
+static struct hard_trap_info
+{
+        unsigned int tt;                /* Trap type code for powerpc */
+        unsigned char signo;            /* Signal that we map this trap into */
+} hard_trap_info[] = {
+        { 0x0100, 0x02 /* SIGINT */  },         /* system reset */
+        { 0x0200, 0x0b /* SIGSEGV */ },         /* machine check */
+        { 0x0300, 0x0b /* SIGSEGV */ },         /* data access */
+        { 0x0400, 0x0b /* SIGSEGV */ },         /* instruction access */
+        { 0x0500, 0x02 /* SIGINT */  },         /* external interrupt */
+        { 0x0600, 0x0a /* SIGBUS */  },         /* alignment */
+        { 0x0700, 0x05 /* SIGTRAP */ },         /* program check */
+        { 0x0800, 0x08 /* SIGFPE */  },         /* fp unavailable */
+        { 0x0900, 0x0e /* SIGALRM */ },         /* decrementer */
+        { 0x0c00, 0x14 /* SIGCHLD */ },         /* system call */
+#if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
+        { 0x2002, 0x05 /* SIGTRAP */ },         /* debug */
+#if defined(CONFIG_FSL_BOOKE)
+        { 0x2010, 0x08 /* SIGFPE */  },         /* spe unavailable */
+        { 0x2020, 0x08 /* SIGFPE */  },         /* spe unavailable */
+        { 0x2030, 0x08 /* SIGFPE */  },         /* spe fp data */
+        { 0x2040, 0x08 /* SIGFPE */  },         /* spe fp data */
+        { 0x2050, 0x08 /* SIGFPE */  },         /* spe fp round */
+        { 0x2060, 0x0e /* SIGILL */  },         /* performace monitor */
+        { 0x2900, 0x08 /* SIGFPE */  },         /* apu unavailable */
+        { 0x3100, 0x0e /* SIGALRM */ },         /* fixed interval timer */
+        { 0x3200, 0x02 /* SIGINT */  },         /* watchdog */
+#else /* ! CONFIG_FSL_BOOKE */
+        { 0x1000, 0x0e /* SIGALRM */ },         /* prog interval timer */
+        { 0x1010, 0x0e /* SIGALRM */ },         /* fixed interval timer */
+        { 0x1020, 0x02 /* SIGINT */  },         /* watchdog */
+        { 0x2010, 0x08 /* SIGFPE */  },         /* fp unavailable */
+        { 0x2020, 0x08 /* SIGFPE */  },         /* ap unavailable */
+#endif
+#else /* ! (defined(CONFIG_40x) || defined(CONFIG_BOOKE)) */
+        { 0x0d00, 0x05 /* SIGTRAP */ },         /* single-step */
+#if defined(CONFIG_8xx)
+        { 0x1000, 0x04 /* SIGILL */  },         /* software emulation */
+#else /* ! CONFIG_8xx */
+        { 0x0f00, 0x04 /* SIGILL */  },         /* performance monitor */
+        { 0x0f20, 0x08 /* SIGFPE */  },         /* altivec unavailable */
+        { 0x1300, 0x05 /* SIGTRAP */ },         /* instruction address break */
+#if defined(CONFIG_PPC64)
+        { 0x1200, 0x05 /* SIGILL */  },         /* system error */
+        { 0x1500, 0x04 /* SIGILL */  },         /* soft patch */
+        { 0x1600, 0x04 /* SIGILL */  },         /* maintenance */
+        { 0x1700, 0x08 /* SIGFPE */  },         /* altivec assist */
+        { 0x1800, 0x04 /* SIGILL */  },         /* thermal */
+#else /* ! CONFIG_PPC64 */
+        { 0x1400, 0x02 /* SIGINT */  },         /* SMI */
+        { 0x1600, 0x08 /* SIGFPE */  },         /* altivec assist */
+        { 0x1700, 0x04 /* SIGILL */  },         /* TAU */
+        { 0x2000, 0x05 /* SIGTRAP */ },         /* run mode */
+#endif
+#endif
+#endif
+        { 0x0000, 0x00 }                        /* Must be last */
+};
+
+static int computeSignal(unsigned int tt)
+{
+        struct hard_trap_info *ht;
+
+        for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
+                if (ht->tt == tt)
+                        return ht->signo;
+
+        return SIGHUP;          /* default for things we don't know about */
+}
+
+static int kgdb_call_nmi_hook(struct pt_regs *regs)
+{
+        kgdb_nmicallback(raw_smp_processor_id(), regs);
+        return 0;
+}
+
+#ifdef CONFIG_SMP
+void kgdb_roundup_cpus(unsigned long flags)
+{
+        smp_send_debugger_break(MSG_ALL_BUT_SELF);
+}
+#endif
+
+/* KGDB functions to use existing PowerPC64 hooks. */
+static int kgdb_debugger(struct pt_regs *regs)
+{
+        return kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs);
+}
+
+static int kgdb_handle_breakpoint(struct pt_regs *regs)
+{
+        if (user_mode(regs))
+                return 0;
+
+        if (kgdb_handle_exception(0, SIGTRAP, 0, regs) != 0)
+                return 0;
+
+        if (*(u32 *) (regs->nip) == *(u32 *) (&arch_kgdb_ops.gdb_bpt_instr))
+                regs->nip += 4;
+
+        return 1;
+}
+
+static int kgdb_singlestep(struct pt_regs *regs)
+{
+        struct thread_info *thread_info, *exception_thread_info;
+
+        if (user_mode(regs))
+                return 0;
+
+        /*
+         * On Book E and perhaps other processsors, singlestep is handled on
+         * the critical exception stack.  This causes current_thread_info()
+         * to fail, since it it locates the thread_info by masking off
+         * the low bits of the current stack pointer.  We work around
+         * this issue by copying the thread_info from the kernel stack
+         * before calling kgdb_handle_exception, and copying it back
+         * afterwards.  On most processors the copy is avoided since
+         * exception_thread_info == thread_info.
+         */
+        thread_info = (struct thread_info *)(regs->gpr[1] & ~(THREAD_SIZE-1));
+        exception_thread_info = current_thread_info();
+
+        if (thread_info != exception_thread_info)
+                memcpy(exception_thread_info, thread_info, sizeof *thread_info);
+
+        kgdb_handle_exception(0, SIGTRAP, 0, regs);
+
+        if (thread_info != exception_thread_info)
+                memcpy(thread_info, exception_thread_info, sizeof *thread_info);
+
+        return 1;
+}
+
+static int kgdb_iabr_match(struct pt_regs *regs)
+{
+        if (user_mode(regs))
+                return 0;
+
+        if (kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs) != 0)
+                return 0;
+        return 1;
+}
+
+static int kgdb_dabr_match(struct pt_regs *regs)
+{
+        if (user_mode(regs))
+                return 0;
+
+        if (kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs) != 0)
+                return 0;
+        return 1;
+}
+
+#define PACK64(ptr, src) do { *(ptr++) = (src); } while (0)
+
+#define PACK32(ptr, src) do {          \
+        u32 *ptr32;                   \
+        ptr32 = (u32 *)ptr;           \
+        *(ptr32++) = (src);           \
+        ptr = (unsigned long *)ptr32; \
+        } while (0)
+
+
+void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
+{
+        unsigned long *ptr = gdb_regs;
+        int reg;
+
+        memset(gdb_regs, 0, NUMREGBYTES);
+
+        for (reg = 0; reg < 32; reg++)
+                PACK64(ptr, regs->gpr[reg]);
+
+#ifdef CONFIG_FSL_BOOKE
+#ifdef CONFIG_SPE
+        for (reg = 0; reg < 32; reg++)
+                PACK64(ptr, current->thread.evr[reg]);
+#else
+        ptr += 32;
+#endif
+#else
+        /* fp registers not used by kernel, leave zero */
+        ptr += 32 * 8 / sizeof(long);
+#endif
+
+        PACK64(ptr, regs->nip);
+        PACK64(ptr, regs->msr);
+        PACK32(ptr, regs->ccr);
+        PACK64(ptr, regs->link);
+        PACK64(ptr, regs->ctr);
+        PACK32(ptr, regs->xer);
+
+        BUG_ON((unsigned long)ptr >
+               (unsigned long)(((void *)gdb_regs) + NUMREGBYTES));
+}
+
+void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
+{
+        struct pt_regs *regs = (struct pt_regs *)(p->thread.ksp +
+                                                  STACK_FRAME_OVERHEAD);
+        unsigned long *ptr = gdb_regs;
+        int reg;
+
+        memset(gdb_regs, 0, NUMREGBYTES);
+
+        /* Regs GPR0-2 */
+        for (reg = 0; reg < 3; reg++)
+                PACK64(ptr, regs->gpr[reg]);
+
+        /* Regs GPR3-13 are caller saved, not in regs->gpr[] */
+        ptr += 11;
+
+        /* Regs GPR14-31 */
+        for (reg = 14; reg < 32; reg++)
+                PACK64(ptr, regs->gpr[reg]);
+
+#ifdef CONFIG_FSL_BOOKE
+#ifdef CONFIG_SPE
+        for (reg = 0; reg < 32; reg++)
+                PACK64(ptr, p->thread.evr[reg]);
+#else
+        ptr += 32;
+#endif
+#else
+        /* fp registers not used by kernel, leave zero */
+        ptr += 32 * 8 / sizeof(long);
+#endif
+
+        PACK64(ptr, regs->nip);
+        PACK64(ptr, regs->msr);
+        PACK32(ptr, regs->ccr);
+        PACK64(ptr, regs->link);
+        PACK64(ptr, regs->ctr);
+        PACK32(ptr, regs->xer);
+
+        BUG_ON((unsigned long)ptr >
+               (unsigned long)(((void *)gdb_regs) + NUMREGBYTES));
+}
+
+#define UNPACK64(dest, ptr) do { dest = *(ptr++); } while (0)
+
+#define UNPACK32(dest, ptr) do {       \
+        u32 *ptr32;                   \
+        ptr32 = (u32 *)ptr;           \
+        dest = *(ptr32++);            \
+        ptr = (unsigned long *)ptr32; \
+        } while (0)
+
+void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
+{
+        unsigned long *ptr = gdb_regs;
+        int reg;
+#ifdef CONFIG_SPE
+        union {
+                u32 v32[2];
+                u64 v64;
+        } acc;
+#endif
+
+        for (reg = 0; reg < 32; reg++)
+                UNPACK64(regs->gpr[reg], ptr);
+
+#ifdef CONFIG_FSL_BOOKE
+#ifdef CONFIG_SPE
+        for (reg = 0; reg < 32; reg++)
+                UNPACK64(current->thread.evr[reg], ptr);
+#else
+        ptr += 32;
+#endif
+#else
+        /* fp registers not used by kernel, leave zero */
+        ptr += 32 * 8 / sizeof(int);
+#endif
+
+        UNPACK64(regs->nip, ptr);
+        UNPACK64(regs->msr, ptr);
+        UNPACK32(regs->ccr, ptr);
+        UNPACK64(regs->link, ptr);
+        UNPACK64(regs->ctr, ptr);
+        UNPACK32(regs->xer, ptr);
+
+        BUG_ON((unsigned long)ptr >
+               (unsigned long)(((void *)gdb_regs) + NUMREGBYTES));
+}
+
+/*
+ * This function does PowerPC specific procesing for interfacing to gdb.
+ */
+int kgdb_arch_handle_exception(int vector, int signo, int err_code,
+                               char *remcom_in_buffer, char *remcom_out_buffer,
+                               struct pt_regs *linux_regs)
+{
+        char *ptr = &remcom_in_buffer[1];
+        unsigned long addr;
+
+        switch (remcom_in_buffer[0]) {
+                /*
+                 * sAA..AA   Step one instruction from AA..AA
+                 * This will return an error to gdb ..
+                 */
+        case 's':
+        case 'c':
+                /* handle the optional parameter */
+                if (kgdb_hex2long(&ptr, &addr))
+                        linux_regs->nip = addr;
+
+                atomic_set(&kgdb_cpu_doing_single_step, -1);
+                /* set the trace bit if we're stepping */
+                if (remcom_in_buffer[0] == 's') {
+#if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
+                        mtspr(SPRN_DBCR0,
+                              mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM);
+                        linux_regs->msr |= MSR_DE;
+#else
+                        linux_regs->msr |= MSR_SE;
+#endif
+                        kgdb_single_step = 1;
+                        if (kgdb_contthread)
+                                atomic_set(&kgdb_cpu_doing_single_step,
+                                           raw_smp_processor_id());
+                }
+                return 0;
+        }
+
+        return -1;
+}
+
+/*
+ * Global data
+ */
+struct kgdb_arch arch_kgdb_ops = {
+        .gdb_bpt_instr = {0x7d, 0x82, 0x10, 0x08},
+};
+
+static int kgdb_not_implemented(struct pt_regs *regs)
+{
+        return 0;
+}
+
+static void *old__debugger_ipi;
+static void *old__debugger;
+static void *old__debugger_bpt;
+static void *old__debugger_sstep;
+static void *old__debugger_iabr_match;
+static void *old__debugger_dabr_match;
+static void *old__debugger_fault_handler;
+
+int kgdb_arch_init(void)
+{
+        old__debugger_ipi = __debugger_ipi;
+        old__debugger = __debugger;
+        old__debugger_bpt = __debugger_bpt;
+        old__debugger_sstep = __debugger_sstep;
+        old__debugger_iabr_match = __debugger_iabr_match;
+        old__debugger_dabr_match = __debugger_dabr_match;
+        old__debugger_fault_handler = __debugger_fault_handler;
+
+        __debugger_ipi = kgdb_call_nmi_hook;
+        __debugger = kgdb_debugger;
+        __debugger_bpt = kgdb_handle_breakpoint;
+        __debugger_sstep = kgdb_singlestep;
+        __debugger_iabr_match = kgdb_iabr_match;
+        __debugger_dabr_match = kgdb_dabr_match;
+        __debugger_fault_handler = kgdb_not_implemented;
+
+        return 0;
+}
+
+void kgdb_arch_exit(void)
+{
+        __debugger_ipi = old__debugger_ipi;
+        __debugger = old__debugger;
+        __debugger_bpt = old__debugger_bpt;
+        __debugger_sstep = old__debugger_sstep;
+        __debugger_iabr_match = old__debugger_iabr_match;
+        __debugger_dabr_match = old__debugger_dabr_match;
+        __debugger_fault_handler = old__debugger_fault_handler;
+}
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index 4efebe88e64a..066e65c59b58 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -43,10 +43,6 @@
 
 #define DBG(fmt...)
 
-#if defined CONFIG_KGDB
-#include <asm/kgdb.h>
-#endif
-
 extern void bootx_init(unsigned long r4, unsigned long phys);
 
 int boot_cpuid;
@@ -302,18 +298,6 @@ void __init setup_arch(char **cmdline_p)
 
         xmon_setup();
 
-#if defined(CONFIG_KGDB)
-        if (ppc_md.kgdb_map_scc)
-                ppc_md.kgdb_map_scc();
-        set_debug_traps();
-        if (strstr(cmd_line, "gdb")) {
-                if (ppc_md.progress)
-                        ppc_md.progress("setup_arch: kgdb breakpoint", 0x4000);
-                printk("kgdb breakpoint activated\n");
-                breakpoint();
-        }
-#endif
-
         /*
          * Set cache line size based on type of cpu as a default.
          * Systems with OF can look in the properties on the cpu node(s)