Signed-off-by: Jason Wessel <[email protected]>
x86_64-lite.patch
From: Jason Wessel <[email protected]>
CC: [email protected]
Subject: [PATCH] This adds support for the x86_64 architecture.
An extra annotation is added to the switch_to in order to aid in stack
tracing from gdb or other external hardware debuggers.
Signed-off-by: Milind Dumbare <[email protected]>
Signed-off-by: Tom Rini <[email protected]>
Signed-off-by: Jason Wessel <[email protected]>
---
arch/x86/kernel/Makefile_64 | 1
arch/x86/kernel/kgdb-jmp_64.S | 65 +++++++
arch/x86/kernel/kgdb_64.c | 384 ++++++++++++++++++++++++++++++++++++++++++
arch/x86/kernel/traps_64.c | 7
arch/x86_64/Kconfig.debug | 3
include/asm-x86/kgdb_64.h | 52 +++++
include/asm-x86/system_64.h | 6
lib/Kconfig.kgdb | 1
8 files changed, 514 insertions(+), 5 deletions(-)
create mode 100644 arch/x86/kernel/kgdb-jmp.S
create mode 100644 arch/x86/kernel/kgdb.c
create mode 100644 include/asm-x86/kgdb.h
--- a/arch/x86_64/Kconfig.debug
+++ b/arch/x86_64/Kconfig.debug
@@ -55,7 +55,4 @@ config DEBUG_STACK_USAGE
This option will slow down process creation somewhat.
-#config X86_REMOTE_DEBUG
-# bool "kgdb debugging stub"
-
endmenu
--- a/arch/x86/kernel/Makefile_64
+++ b/arch/x86/kernel/Makefile_64
@@ -33,6 +33,7 @@ obj-$(CONFIG_IOMMU) += pci-gart_64.o ap
obj-$(CONFIG_CALGARY_IOMMU) += pci-calgary_64.o tce_64.o
obj-$(CONFIG_SWIOTLB) += pci-swiotlb_64.o
obj-$(CONFIG_KPROBES) += kprobes_64.o
+obj-$(CONFIG_KGDB) += kgdb_64.o kgdb-jmp_64.o
obj-$(CONFIG_X86_PM_TIMER) += pmtimer_64.o
obj-$(CONFIG_X86_VSMP) += vsmp_64.o
obj-$(CONFIG_K8_NB) += k8.o
--- /dev/null
+++ b/arch/x86/kernel/kgdb-jmp_64.S
@@ -0,0 +1,65 @@
+/*
+ * arch/x86/kernel/kgdb-jmp.S
+ *
+ * Save and restore system registers so that within a limited frame we
+ * may have a fault and "jump back" to a known safe location.
+ *
+ * Author: Tom Rini <[email protected]>
+ *
+ * Cribbed from glibc, which carries the following:
+ * Copyright (C) 2001, 2003, 2004 Free Software Foundation, Inc.
+ * Copyright (C) 2005 by MontaVista Software.
+ *
+ * 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/linkage.h>
+
+#define JB_RBX 0
+#define JB_RBP 1
+#define JB_R12 2
+#define JB_R13 3
+#define JB_R14 4
+#define JB_R15 5
+#define JB_RSP 6
+#define JB_PC 7
+
+ .code64
+
+/* This must be called prior to kgdb_fault_longjmp and
+ * kgdb_fault_longjmp must not be called outside of the context of the
+ * last call to kgdb_fault_setjmp.
+ */
+ENTRY(kgdb_fault_setjmp)
+ /* Save registers. */
+ movq %rbx, (JB_RBX*8)(%rdi)
+ movq %rbp, (JB_RBP*8)(%rdi)
+ movq %r12, (JB_R12*8)(%rdi)
+ movq %r13, (JB_R13*8)(%rdi)
+ movq %r14, (JB_R14*8)(%rdi)
+ movq %r15, (JB_R15*8)(%rdi)
+ leaq 8(%rsp), %rdx /* Save SP as it will be after we return. */
+ movq %rdx, (JB_RSP*8)(%rdi)
+ movq (%rsp), %rax /* Save PC we are returning to now. */
+ movq %rax, (JB_PC*8)(%rdi)
+ /* Set return value for setjmp. */
+ mov $0,%eax
+ movq (JB_PC*8)(%rdi),%rdx
+ movq (JB_RSP*8)(%rdi),%rsp
+ jmpq *%rdx
+
+ENTRY(kgdb_fault_longjmp)
+ /* Restore registers. */
+ movq (JB_RBX*8)(%rdi),%rbx
+ movq (JB_RBP*8)(%rdi),%rbp
+ movq (JB_R12*8)(%rdi),%r12
+ movq (JB_R13*8)(%rdi),%r13
+ movq (JB_R14*8)(%rdi),%r14
+ movq (JB_R15*8)(%rdi),%r15
+ /* Set return value for setjmp. */
+ movq (JB_PC*8)(%rdi),%rdx
+ movq (JB_RSP*8)(%rdi),%rsp
+ mov $1,%eax
+ jmpq *%rdx
--- /dev/null
+++ b/arch/x86/kernel/kgdb_64.c
@@ -0,0 +1,384 @@
+/*
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2, or (at your option) any
+ * later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ */
+
+/*
+ * Copyright (C) 2004 Amit S. Kale <[email protected]>
+ * Copyright (C) 2000-2001 VERITAS Software Corporation.
+ * Copyright (C) 2002 Andi Kleen, SuSE Labs
+ * Copyright (C) 2004 LinSysSoft Technologies Pvt. Ltd.
+ */
+/****************************************************************************
+ * Contributor: Lake Stevens Instrument Division$
+ * Written by: Glenn Engel $
+ * Updated by: Amit Kale<[email protected]>
+ * Modified for 386 by Jim Kingdon, Cygnus Support.
+ * Origianl kgdb, compatibility with 2.1.xx kernel by
+ * David Grothe <[email protected]>
+ * Integrated into 2.2.5 kernel by Tigran Aivazian <[email protected]>
+ * X86_64 changes from Andi Kleen's patch merged by Jim Houston
+ */
+
+#include <linux/string.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/smp.h>
+#include <linux/spinlock.h>
+#include <linux/delay.h>
+#include <asm/system.h>
+#include <linux/ptrace.h> /* for linux pt_regs struct */
+#include <linux/kgdb.h>
+#include <linux/init.h>
+#include <linux/kdebug.h>
+#include <asm/apicdef.h>
+#include <asm/mach_apic.h>
+#include <asm/debugreg.h>
+
+/* Put the error code here just in case the user cares. */
+int gdb_x86_64errcode;
+/* Likewise, the vector number here (since GDB only gets the signal
+ number through the usual means, and that's not very specific). */
+int gdb_x86_64vector = -1;
+
+void regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
+{
+ gdb_regs[_RAX] = regs->rax;
+ gdb_regs[_RBX] = regs->rbx;
+ gdb_regs[_RCX] = regs->rcx;
+ gdb_regs[_RDX] = regs->rdx;
+ gdb_regs[_RSI] = regs->rsi;
+ gdb_regs[_RDI] = regs->rdi;
+ gdb_regs[_RBP] = regs->rbp;
+ gdb_regs[_PS] = regs->eflags;
+ gdb_regs[_PC] = regs->rip;
+ gdb_regs[_R8] = regs->r8;
+ gdb_regs[_R9] = regs->r9;
+ gdb_regs[_R10] = regs->r10;
+ gdb_regs[_R11] = regs->r11;
+ gdb_regs[_R12] = regs->r12;
+ gdb_regs[_R13] = regs->r13;
+ gdb_regs[_R14] = regs->r14;
+ gdb_regs[_R15] = regs->r15;
+ gdb_regs[_RSP] = regs->rsp;
+}
+
+extern void thread_return(void);
+void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
+{
+ gdb_regs[_RAX] = 0;
+ gdb_regs[_RBX] = 0;
+ gdb_regs[_RCX] = 0;
+ gdb_regs[_RDX] = 0;
+ gdb_regs[_RSI] = 0;
+ gdb_regs[_RDI] = 0;
+ gdb_regs[_RBP] = *(unsigned long *)p->thread.rsp;
+ gdb_regs[_PS] = *(unsigned long *)(p->thread.rsp + 8);
+ gdb_regs[_PC] = (unsigned long)&thread_return;
+ gdb_regs[_R8] = 0;
+ gdb_regs[_R9] = 0;
+ gdb_regs[_R10] = 0;
+ gdb_regs[_R11] = 0;
+ gdb_regs[_R12] = 0;
+ gdb_regs[_R13] = 0;
+ gdb_regs[_R14] = 0;
+ gdb_regs[_R15] = 0;
+ gdb_regs[_RSP] = p->thread.rsp;
+}
+
+void gdb_regs_to_regs(unsigned long *gdb_regs, struct pt_regs *regs)
+{
+ regs->rax = gdb_regs[_RAX];
+ regs->rbx = gdb_regs[_RBX];
+ regs->rcx = gdb_regs[_RCX];
+ regs->rdx = gdb_regs[_RDX];
+ regs->rsi = gdb_regs[_RSI];
+ regs->rdi = gdb_regs[_RDI];
+ regs->rbp = gdb_regs[_RBP];
+ regs->eflags = gdb_regs[_PS];
+ regs->rip = gdb_regs[_PC];
+ regs->r8 = gdb_regs[_R8];
+ regs->r9 = gdb_regs[_R9];
+ regs->r10 = gdb_regs[_R10];
+ regs->r11 = gdb_regs[_R11];
+ regs->r12 = gdb_regs[_R12];
+ regs->r13 = gdb_regs[_R13];
+ regs->r14 = gdb_regs[_R14];
+ regs->r15 = gdb_regs[_R15];
+} /* gdb_regs_to_regs */
+
+struct hw_breakpoint {
+ unsigned enabled;
+ unsigned type;
+ unsigned len;
+ unsigned long addr;
+} breakinfo[4] = {
+ {enabled:0},
+ {enabled:0},
+ {enabled:0},
+ {enabled:0}
+};
+
+void kgdb_disable_hw_debug(struct pt_regs *regs)
+{
+ /* Disable hardware debugging while we are in kgdb */
+ asm volatile ("movq %0,%%db7": /* no output */ :"r" (0UL));
+}
+
+void kgdb_post_master_code(struct pt_regs *regs, int e_vector, int err_code)
+{
+ /* Master processor is completely in the debugger */
+ gdb_x86_64vector = e_vector;
+ gdb_x86_64errcode = err_code;
+}
+
+void kgdb_roundup_cpus(unsigned long flags)
+{
+ send_IPI_allbutself(APIC_DM_NMI);
+}
+
+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;
+ unsigned long breakno;
+ char *ptr;
+ int newPC;
+ unsigned long dr6;
+
+ 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->rip = addr;
+ newPC = linux_regs->rip;
+
+ /* clear the trace bit */
+ linux_regs->eflags &= ~TF_MASK;
+
+ atomic_set(&cpu_doing_single_step, -1);
+ /* set the trace bit if we're stepping */
+ if (remcomInBuffer[0] == 's') {
+ linux_regs->eflags |= TF_MASK;
+ debugger_step = 1;
+ if (kgdb_contthread)
+ atomic_set(&cpu_doing_single_step,
+ raw_smp_processor_id());
+
+ }
+
+ asm volatile ("movq %%db6, %0\n":"=r" (dr6));
+ if (!(dr6 & 0x4000)) {
+ for (breakno = 0; breakno < 4; ++breakno) {
+ if (dr6 & (1 << breakno)) {
+ if (breakinfo[breakno].type == 0) {
+ /* Set restore flag */
+ linux_regs->eflags |=
+ X86_EFLAGS_RF;
+ break;
+ }
+ }
+ }
+ }
+ asm volatile ("movq %0, %%db6\n"::"r" (0UL));
+
+ return 0;
+ }
+ /* this means that we do not want to exit from the handler */
+ return -1;
+}
+
+static struct pt_regs *in_interrupt_stack(unsigned long rsp, int cpu)
+{
+ struct pt_regs *regs = NULL;
+ unsigned long end = (unsigned long)cpu_pda(cpu)->irqstackptr;
+
+ if (rsp <= end && rsp >= end - IRQSTACKSIZE + 8)
+ regs = *(((struct pt_regs **)end) - 1);
+
+ return regs;
+}
+
+static struct pt_regs *in_exception_stack(unsigned long rsp, int cpu)
+{
+ struct tss_struct *init_tss = &__get_cpu_var(init_tss);
+ struct pt_regs *regs;
+ int i;
+
+ for (i = 0; i < N_EXCEPTION_STACKS; i++)
+ if (rsp >= init_tss[cpu].ist[i] &&
+ rsp <= init_tss[cpu].ist[i] + EXCEPTION_STKSZ) {
+ regs = (void *) init_tss[cpu].ist[i] + EXCEPTION_STKSZ;
+ return regs - 1;
+ }
+
+ return NULL;
+}
+
+void kgdb_shadowinfo(struct pt_regs *regs, char *buffer, unsigned threadid)
+{
+ static char intr_desc[] = "Stack at interrupt entrypoint";
+ static char exc_desc[] = "Stack at exception entrypoint";
+ struct pt_regs *stregs;
+ int cpu = raw_smp_processor_id();
+ stregs = in_interrupt_stack(regs->rsp, cpu);
+ if (stregs)
+ kgdb_mem2hex(intr_desc, buffer, strlen(intr_desc));
+ else {
+ stregs = in_exception_stack(regs->rsp, cpu);
+ if (stregs)
+ kgdb_mem2hex(exc_desc, buffer, strlen(exc_desc));
+ }
+}
+
+struct task_struct *kgdb_get_shadow_thread(struct pt_regs *regs, int threadid)
+{
+ struct pt_regs *stregs;
+ int cpu = raw_smp_processor_id();
+
+ stregs = in_interrupt_stack(regs->rsp, cpu);
+ if (stregs)
+ return current;
+ else {
+ stregs = in_exception_stack(regs->rsp, cpu);
+ if (stregs)
+ return current;
+ }
+
+ return NULL;
+}
+
+struct pt_regs *kgdb_shadow_regs(struct pt_regs *regs, int threadid)
+{
+ struct pt_regs *stregs;
+ int cpu = raw_smp_processor_id();
+
+ stregs = in_interrupt_stack(regs->rsp, cpu);
+ if (stregs)
+ return stregs;
+ else {
+ stregs = in_exception_stack(regs->rsp, cpu);
+ if (stregs)
+ return stregs;
+ }
+
+ return NULL;
+}
+
+static inline int single_step_cont(struct pt_regs *regs,
+ struct die_args *args)
+{
+ /* single step exception from kernel space to user space so
+ * eat the exception and continue the process
+ */
+ printk(KERN_ERR "KGDB: trap/step from kernel to user space,"
+ " resuming...\n");
+ kgdb_arch_handle_exception(args->trapnr, args->signr,
+ args->err, "c", "", regs);
+
+ return NOTIFY_STOP;
+}
+
+static int kgdb_notify(struct notifier_block *self, unsigned long cmd,
+ void *ptr)
+{
+ struct die_args *args = ptr;
+ struct pt_regs *regs = args->regs;
+
+ switch (cmd) {
+ case DIE_NMI:
+ if (atomic_read(&debugger_active)) {
+ /* KGDB CPU roundup */
+ kgdb_nmihook(raw_smp_processor_id(), regs);
+ return NOTIFY_STOP;
+ }
+ return NOTIFY_DONE;
+ case DIE_NMI_IPI:
+ if (atomic_read(&debugger_active)) {
+ /* KGDB CPU roundup */
+ if (kgdb_nmihook(raw_smp_processor_id(), regs))
+ return NOTIFY_DONE;
+ return NOTIFY_STOP;
+ }
+ return NOTIFY_DONE;
+ case DIE_NMIWATCHDOG:
+ if (atomic_read(&debugger_active)) {
+ /* KGDB CPU roundup */
+ kgdb_nmihook(raw_smp_processor_id(), regs);
+ return NOTIFY_STOP;
+ }
+ /* Enter debugger */
+ break;
+ case DIE_DEBUG:
+ if (atomic_read(&cpu_doing_single_step) ==
+ raw_smp_processor_id() &&
+ user_mode(regs))
+ return single_step_cont(regs, args);
+ /* fall through */
+ default:
+ if (user_mode(regs))
+ return NOTIFY_DONE;
+ }
+
+ if (kgdb_may_fault) {
+ kgdb_fault_longjmp(kgdb_fault_jmp_regs);
+ return NOTIFY_STOP;
+ }
+
+ if (kgdb_handle_exception(args->trapnr, args->signr,
+ args->err, regs))
+ return NOTIFY_DONE;
+
+ return NOTIFY_STOP;
+}
+
+static struct notifier_block kgdb_notifier = {
+ .notifier_call = kgdb_notify,
+ .priority = 0x7fffffff, /* we need to be notified first */
+};
+
+int kgdb_arch_init(void)
+{
+ register_die_notifier(&kgdb_notifier);
+ return 0;
+}
+
+/*
+ * Skip an int3 exception when it occurs after a breakpoint has been
+ * removed. Backtrack eip by 1 since the int3 would have caused it to
+ * increment by 1.
+ */
+
+int kgdb_skipexception(int exception, struct pt_regs *regs)
+{
+ if (exception == 3 && kgdb_isremovedbreak(regs->rip - 1)) {
+ regs->rip -= 1;
+ return 1;
+ }
+ return 0;
+}
+
+unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs)
+{
+ if (exception == 3)
+ return instruction_pointer(regs) - 1;
+ return instruction_pointer(regs);
+}
+
+struct kgdb_arch arch_kgdb_ops = {
+ .gdb_bpt_instr = {0xcc},
+ .flags = KGDB_HW_BREAKPOINT,
+ .shadowth = 1,
+};
--- /dev/null
+++ b/include/asm-x86/kgdb_64.h
@@ -0,0 +1,52 @@
+#ifdef __KERNEL__
+#ifndef _ASM_KGDB_H_
+#define _ASM_KGDB_H_
+
+/*
+ * Copyright (C) 2001-2004 Amit S. Kale
+ */
+
+#include <asm-generic/kgdb.h>
+
+/*
+ * Note that this register image is in a different order than
+ * the register image that Linux produces at interrupt time.
+ *
+ * Linux's register image is defined by struct pt_regs in ptrace.h.
+ * Just why GDB uses a different order is a historical mystery.
+ */
+#define _RAX 0
+#define _RDX 1
+#define _RCX 2
+#define _RBX 3
+#define _RSI 4
+#define _RDI 5
+#define _RBP 6
+#define _RSP 7
+#define _R8 8
+#define _R9 9
+#define _R10 10
+#define _R11 11
+#define _R12 12
+#define _R13 13
+#define _R14 14
+#define _R15 15
+#define _PC 16
+#define _PS 17
+
+/* Number of bytes of registers. */
+#define NUMREGBYTES ((_PS+1)*8)
+#define NUMCRITREGBYTES (8 * 8) /* 8 registers. */
+
+#ifndef __ASSEMBLY__
+/* BUFMAX defines the maximum number of characters in inbound/outbound
+ * buffers at least NUMREGBYTES*2 are needed for register packets, and
+ * a longer buffer is needed to list all threads. */
+#define BUFMAX 1024
+#define BREAKPOINT() asm(" int $3");
+#define CHECK_EXCEPTION_STACK() ((&__get_cpu_var(init_tss))[0].ist[0])
+#define BREAK_INSTR_SIZE 1
+#define CACHE_FLUSH_IS_SAFE 1
+#endif /* !__ASSEMBLY__ */
+#endif /* _ASM_KGDB_H_ */
+#endif /* __KERNEL__ */
--- a/include/asm-x86/system_64.h
+++ b/include/asm-x86/system_64.h
@@ -22,7 +22,9 @@
/* Save restore flags to clear handle leaking NT */
#define switch_to(prev,next,last) \
- asm volatile(SAVE_CONTEXT \
+ asm volatile(".globl __switch_to_begin\n\t" \
+ "__switch_to_begin:\n\t" \
+ SAVE_CONTEXT \
"movq %%rsp,%P[threadrsp](%[prev])\n\t" /* save RSP */ \
"movq %P[threadrsp](%[next]),%%rsp\n\t" /* restore RSP */ \
"call __switch_to\n\t" \
@@ -34,6 +36,8 @@
"movq %%rax,%%rdi\n\t" \
"jc ret_from_fork\n\t" \
RESTORE_CONTEXT \
+ "\n.globl __switch_to_end\n\t" \
+ "__switch_to_end:\n\t" \
: "=a" (last) \
: [next] "S" (next), [prev] "D" (prev), \
[threadrsp] "i" (offsetof(struct task_struct, thread.rsp)), \
--- a/lib/Kconfig.kgdb
+++ b/lib/Kconfig.kgdb
@@ -13,6 +13,7 @@ config UNWIND_INFO
config KGDB
bool "KGDB: kernel debugging with remote gdb"
select WANT_EXTRA_DEBUG_INFORMATION
+ select KGDB_ARCH_HAS_SHADOW_INFO if X86_64
depends on DEBUG_KERNEL && (X86 || MIPS || IA64 || PPC)
help
If you say Y here, it will be possible to remotely debug the
--- a/arch/x86/kernel/traps_64.c
+++ b/arch/x86/kernel/traps_64.c
@@ -546,8 +546,13 @@ void die(const char * str, struct pt_reg
void __kprobes die_nmi(char *str, struct pt_regs *regs, int do_panic)
{
- unsigned long flags = oops_begin();
+ unsigned long flags;
+ if (notify_die(DIE_NMIWATCHDOG, "nmi", regs, 0, 2, SIGINT)
+ == NOTIFY_STOP)
+ return;
+
+ flags = oops_begin();
/*
* We are in trouble anyway, lets at least try
* to get a message out.
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