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Subject[PATCH 1/3] reliable stack trace support
These are the generic bits needed to enable reliable stack traces based
on Dwarf2-like (.eh_frame) unwind information. Subsequent patches will
enable x86-64 and i386 to make use of this.

Signed-off-by: Jan Beulich <jbeulich@novell.com>

--- linux-2.6.17-rc4/include/asm-generic/unwind.h 1970-01-01 01:00:00.000000000 +0100
+++ 2.6.17-rc4-unwind-generic/include/asm-generic/unwind.h 2006-05-16 14:36:21.000000000 +0200
@@ -0,0 +1,119 @@
+#ifndef _ASM_GENERIC_UNWIND_H
+#define _ASM_GENERIC_UNWIND_H
+
+/*
+ * Copyright (C) 2002-2006 Novell, Inc.
+ * Jan Beulich <jbeulich@novell.com>
+ *
+ * A simple API for unwinding kernel stacks. This is used for
+ * debugging and error reporting purposes. The kernel doesn't need
+ * full-blown stack unwinding with all the bells and whistles, so there
+ * is not much point in implementing the full Dwarf2 unwind API.
+ */
+
+struct module;
+
+#ifdef CONFIG_STACK_UNWIND
+
+#define ARCH_UNWIND_SECTION_NAME ".eh_frame"
+
+/*
+ * Initialize unwind support.
+ */
+extern void unwind_init(void);
+
+extern void *
+unwind_add_table(struct module *,
+ const void *table_start,
+ unsigned long table_size);
+
+extern void
+unwind_remove_table(void *handle, int init_only);
+
+extern int
+unwind_init_frame_info(struct unwind_frame_info *,
+ struct task_struct *,
+ /*const*/ struct pt_regs *);
+
+/*
+ * Prepare to unwind a blocked task.
+ */
+extern int
+unwind_init_blocked(struct unwind_frame_info *, struct task_struct *);
+
+/*
+ * Prepare to unwind the currently running thread.
+ */
+extern int
+unwind_init_running(struct unwind_frame_info *,
+ asmlinkage void (*callback)(struct unwind_frame_info *, void *arg),
+ void *arg);
+
+/*
+ * Unwind to previous to frame. Returns 0 if successful, negative
+ * number in case of an error.
+ */
+extern int
+unwind(struct unwind_frame_info *);
+
+/*
+ * Unwind until the return pointer is in user-land (or until an error
+ * occurs). Returns 0 if successful, negative number in case of
+ * error.
+ */
+extern int
+unwind_to_user(struct unwind_frame_info *);
+
+#else
+
+struct unwind_frame_info {};
+
+static inline void unwind_init(void) {}
+
+static inline void *
+unwind_add_table(struct module *mod,
+ const void *table_start,
+ unsigned long table_size)
+{
+ return NULL;
+}
+
+static inline void
+unwind_remove_table(void *handle, int init_only)
+{}
+
+static inline int
+unwind_init_frame_info(struct unwind_frame_info *info,
+ struct task_struct *tsk,
+ const struct pt_regs *regs)
+{
+ return -ENOSYS;
+}
+
+static inline int
+unwind_init_blocked(struct unwind_frame_info *info, struct task_struct *tsk)
+{
+ return -ENOSYS;
+}
+
+static inline int
+unwind_init_running(struct unwind_frame_info *info,
+ asmlinkage void (*callback)(struct unwind_frame_info *, void *arg),
+ void *arg)
+{
+ return -ENOSYS;
+}
+
+static inline int unwind(struct unwind_frame_info *info)
+{
+ return -ENOSYS;
+}
+
+static inline int unwind_to_user(struct unwind_frame_info *info)
+{
+ return -ENOSYS;
+}
+
+#endif
+
+#endif /* _ASM_GENERIC_UNWIND_H */
--- linux-2.6.17-rc4/include/linux/module.h 2006-05-16 15:15:48.000000000 +0200
+++ 2.6.17-rc4-unwind-generic/include/linux/module.h 2006-05-15 17:59:46.000000000 +0200
@@ -284,6 +284,12 @@ struct module
/* The size of the executable code in each section. */
unsigned long init_text_size, core_text_size;

+#if defined(CONFIG_STACK_UNWIND) /* || defined(CONFIG_IA64) || defined(CONFIG_PARISC) */
+# define MODULE_UNWIND_INFO
+ /* The handle returned from unwind_add_table. */
+ void *unwind_info;
+#endif
+
/* Arch-specific module values */
struct mod_arch_specific arch;

--- linux-2.6.17-rc4/init/main.c 2006-05-16 15:15:49.000000000 +0200
+++ 2.6.17-rc4-unwind-generic/init/main.c 2006-05-15 17:26:14.000000000 +0200
@@ -54,6 +54,12 @@
#include <asm/sections.h>
#include <asm/cacheflush.h>

+#ifdef CONFIG_STACK_UNWIND
+#include <asm/unwind.h>
+#else
+#include <asm-generic/unwind.h>
+#endif
+
#ifdef CONFIG_X86_LOCAL_APIC
#include <asm/smp.h>
#endif
@@ -482,6 +488,7 @@ asmlinkage void __init start_kernel(void
__stop___param - __start___param,
&unknown_bootoption);
sort_main_extable();
+ unwind_init();
trap_init();
rcu_init();
init_IRQ();
--- linux-2.6.17-rc4/kernel/Makefile 2006-05-16 15:15:49.000000000 +0200
+++ 2.6.17-rc4-unwind-generic/kernel/Makefile 2006-05-15 08:52:50.000000000 +0200
@@ -22,6 +22,7 @@ obj-$(CONFIG_UID16) += uid16.o
obj-$(CONFIG_MODULES) += module.o
obj-$(CONFIG_OBSOLETE_INTERMODULE) += intermodule.o
obj-$(CONFIG_KALLSYMS) += kallsyms.o
+obj-$(CONFIG_STACK_UNWIND) += unwind.o
obj-$(CONFIG_PM) += power/
obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
obj-$(CONFIG_KEXEC) += kexec.o
--- linux-2.6.17-rc4/kernel/module.c 2006-05-16 15:15:49.000000000 +0200
+++ 2.6.17-rc4-unwind-generic/kernel/module.c 2006-05-16 08:46:46.000000000 +0200
@@ -43,6 +43,9 @@
#include <asm/uaccess.h>
#include <asm/semaphore.h>
#include <asm/cacheflush.h>
+#ifdef MODULE_UNWIND_INFO
+#include <asm/unwind.h>
+#endif

#if 0
#define DEBUGP printk
@@ -1051,6 +1054,10 @@ static void free_module(struct module *m
remove_sect_attrs(mod);
mod_kobject_remove(mod);

+#ifdef MODULE_UNWIND_INFO
+ unwind_remove_table(mod->unwind_info, 0);
+#endif
+
/* Arch-specific cleanup. */
module_arch_cleanup(mod);

@@ -1412,7 +1419,7 @@ static struct module *load_module(void _
unsigned int i, symindex = 0, strindex = 0, setupindex, exindex,
exportindex, modindex, obsparmindex, infoindex, gplindex,
crcindex, gplcrcindex, versindex, pcpuindex, gplfutureindex,
- gplfuturecrcindex;
+ gplfuturecrcindex, unwindex = 0;
struct module *mod;
long err = 0;
void *percpu = NULL, *ptr = NULL; /* Stops spurious gcc warning */
@@ -1502,6 +1509,9 @@ static struct module *load_module(void _
versindex = find_sec(hdr, sechdrs, secstrings, "__versions");
infoindex = find_sec(hdr, sechdrs, secstrings, ".modinfo");
pcpuindex = find_pcpusec(hdr, sechdrs, secstrings);
+#ifdef ARCH_UNWIND_SECTION_NAME
+ unwindex = find_sec(hdr, sechdrs, secstrings, ARCH_UNWIND_SECTION_NAME);
+#endif

/* Don't keep modinfo section */
sechdrs[infoindex].sh_flags &= ~(unsigned long)SHF_ALLOC;
@@ -1510,6 +1520,8 @@ static struct module *load_module(void _
sechdrs[symindex].sh_flags |= SHF_ALLOC;
sechdrs[strindex].sh_flags |= SHF_ALLOC;
#endif
+ if (unwindex)
+ sechdrs[unwindex].sh_flags |= SHF_ALLOC;

/* Check module struct version now, before we try to use module. */
if (!check_modstruct_version(sechdrs, versindex, mod)) {
@@ -1738,6 +1750,13 @@ static struct module *load_module(void _
goto arch_cleanup;
add_sect_attrs(mod, hdr->e_shnum, secstrings, sechdrs);

+#ifdef MODULE_UNWIND_INFO
+ /* Size of section 0 is 0, so this works well if no unwind info. */
+ mod->unwind_info = unwind_add_table(mod,
+ (void *)sechdrs[unwindex].sh_addr,
+ sechdrs[unwindex].sh_size);
+#endif
+
/* Get rid of temporary copy */
vfree(hdr);

@@ -1836,6 +1855,9 @@ sys_init_module(void __user *umod,
mod->state = MODULE_STATE_LIVE;
/* Drop initial reference. */
module_put(mod);
+#ifdef MODULE_UNWIND_INFO
+ unwind_remove_table(mod->unwind_info, 1);
+#endif
module_free(mod, mod->module_init);
mod->module_init = NULL;
mod->init_size = 0;
--- linux-2.6.17-rc4/kernel/unwind.c 1970-01-01 01:00:00.000000000 +0100
+++ 2.6.17-rc4-unwind-generic/kernel/unwind.c 2006-05-16 14:36:08.000000000 +0200
@@ -0,0 +1,876 @@
+/*
+ * Copyright (C) 2002-2006 Novell, Inc.
+ * Jan Beulich <jbeulich@novell.com>
+ *
+ * A simple API for unwinding kernel stacks. This is used for
+ * debugging and error reporting purposes. The kernel doesn't need
+ * full-blown stack unwinding with all the bells and whistles, so there
+ * is not much point in implementing the full Dwarf2 unwind API.
+ */
+
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/delay.h>
+#include <asm/sections.h>
+#include <asm/uaccess.h>
+#include <asm/unaligned.h>
+#include <asm/unwind.h>
+
+extern char __start_unwind[], __end_unwind[];
+
+#define MAX_STACK_DEPTH 8
+
+#define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f))
+#define VALUE_BUILD_BUG_ON(e) (sizeof(char[1 - 2 * !!(e)]))
+
+#define EXTRA_INFO(f) { \
+ VALUE_BUILD_BUG_ON(offsetof(struct unwind_frame_info, f) \
+ % FIELD_SIZEOF(struct unwind_frame_info, f)) \
+ * offsetof(struct unwind_frame_info, f) / FIELD_SIZEOF(struct unwind_frame_info, f), \
+ FIELD_SIZEOF(struct unwind_frame_info, f) \
+ }
+#define PTREGS_INFO(f) EXTRA_INFO(regs.f)
+
+static const struct {
+ unsigned offs:BITS_PER_LONG / 2;
+ unsigned width:BITS_PER_LONG / 2;
+} reg_info[] = {
+ UNW_REGISTER_INFO
+};
+
+#undef PTREGS_INFO
+#undef EXTRA_INFO
+
+#ifndef REG_INVALID
+#define REG_INVALID(r) (reg_info[r].width == 0)
+#endif
+
+#define DW_CFA_nop 0x00
+#define DW_CFA_set_loc 0x01
+#define DW_CFA_advance_loc1 0x02
+#define DW_CFA_advance_loc2 0x03
+#define DW_CFA_advance_loc4 0x04
+#define DW_CFA_offset_extended 0x05
+#define DW_CFA_restore_extended 0x06
+#define DW_CFA_undefined 0x07
+#define DW_CFA_same_value 0x08
+#define DW_CFA_register 0x09
+#define DW_CFA_remember_state 0x0a
+#define DW_CFA_restore_state 0x0b
+#define DW_CFA_def_cfa 0x0c
+#define DW_CFA_def_cfa_register 0x0d
+#define DW_CFA_def_cfa_offset 0x0e
+#define DW_CFA_def_cfa_expression 0x0f
+#define DW_CFA_expression 0x10
+#define DW_CFA_offset_extended_sf 0x11
+#define DW_CFA_def_cfa_sf 0x12
+#define DW_CFA_def_cfa_offset_sf 0x13
+#define DW_CFA_val_offset 0x14
+#define DW_CFA_val_offset_sf 0x15
+#define DW_CFA_val_expression 0x16
+#define DW_CFA_lo_user 0x1c
+#define DW_CFA_GNU_window_save 0x2d
+#define DW_CFA_GNU_args_size 0x2e
+#define DW_CFA_GNU_negative_offset_extended 0x2f
+#define DW_CFA_hi_user 0x3f
+
+#define DW_EH_PE_FORM 0x07
+#define DW_EH_PE_native 0x00
+#define DW_EH_PE_leb128 0x01
+#define DW_EH_PE_data2 0x02
+#define DW_EH_PE_data4 0x03
+#define DW_EH_PE_data8 0x04
+#define DW_EH_PE_signed 0x08
+#define DW_EH_PE_ADJUST 0x70
+#define DW_EH_PE_abs 0x00
+#define DW_EH_PE_pcrel 0x10
+#define DW_EH_PE_textrel 0x20
+#define DW_EH_PE_datarel 0x30
+#define DW_EH_PE_funcrel 0x40
+#define DW_EH_PE_aligned 0x50
+#define DW_EH_PE_indirect 0x80
+#define DW_EH_PE_omit 0xff
+
+typedef unsigned long uleb128_t;
+typedef signed long sleb128_t;
+
+DEFINE_SPINLOCK(table_lock);
+static atomic_t lookups, removals;
+
+static struct unwind_table {
+ struct {
+ unsigned long pc;
+ unsigned long range;
+ } core, init;
+ const void *address;
+ unsigned long size;
+ struct unwind_table *link;
+ atomic_t users;
+ const char *name;
+} root_table, *last_table;
+
+struct unwind_item {
+ enum item_location {
+ Nowhere,
+ Memory,
+ Register,
+ Value
+ } where;
+ uleb128_t value;
+};
+
+struct unwind_state {
+ uleb128_t loc, org;
+ const uint8_t *cieStart, *cieEnd;
+ uleb128_t codeAlign;
+ sleb128_t dataAlign;
+ struct cfa {
+ uleb128_t reg, offs;
+ } cfa;
+ struct unwind_item regs[ARRAY_SIZE(reg_info)];
+ unsigned stackDepth:8;
+ unsigned version:8;
+ const uint8_t *label;
+ const uint8_t *stack[MAX_STACK_DEPTH];
+};
+
+static const struct cfa badCFA = {ARRAY_SIZE(reg_info), 1};
+
+static struct unwind_table *
+find_table(unsigned long pc)
+{
+ int old_removals;
+ struct unwind_table *table = NULL;
+
+ do {
+ if (table)
+ atomic_dec(&table->users);
+ old_removals = atomic_read(&removals);
+ atomic_inc(&lookups);
+ for (table = &root_table; table; table = table->link)
+ if ((pc >= table->core.pc && pc < table->core.pc + table->core.range)
+ || (pc >= table->init.pc && pc < table->init.pc + table->init.range)) {
+ atomic_inc(&table->users);
+ break;
+ }
+ atomic_dec(&lookups);
+ } while (atomic_read(&removals) != old_removals);
+ return table;
+}
+
+static void
+drop_table(struct unwind_table *table)
+{
+ if (table)
+ atomic_dec(&table->users);
+}
+
+static void
+init_unwind_table (struct unwind_table *table, const char *name,
+ const void *core_start, unsigned long core_size,
+ const void *init_start, unsigned long init_size,
+ const void *table_start, unsigned long table_size)
+{
+ table->core.pc = (unsigned long)core_start;
+ table->core.range = core_size;
+ table->init.pc = (unsigned long)init_start;
+ table->init.range = init_size;
+ table->address = table_start;
+ table->size = table_size;
+ table->link = NULL;
+ atomic_set(&table->users, 0);
+ table->name = name;
+}
+
+/*
+ * Initialize unwind support.
+ */
+void __init
+unwind_init(void)
+{
+ init_unwind_table(&root_table, "kernel",
+ _text, _end - _text,
+ NULL, 0,
+ __start_unwind, __end_unwind - __start_unwind);
+}
+
+void *
+unwind_add_table(struct module *module,
+ const void *table_start,
+ unsigned long table_size)
+{
+ struct unwind_table *table;
+
+ if (table_size <= 0)
+ return NULL;
+
+ table = kmalloc(sizeof(*table), GFP_USER);
+ if (!table)
+ return NULL;
+
+ init_unwind_table(table, module->name,
+ module->module_core, module->core_size,
+ module->module_init, module->init_size,
+ table_start, table_size);
+
+ spin_lock(&table_lock);
+ if (last_table)
+ last_table->link = table;
+ else
+ root_table.link = table;
+ last_table = table;
+ spin_unlock(&table_lock);
+
+ return table;
+}
+
+void
+unwind_remove_table(void *handle, int init_only)
+{
+ struct unwind_table *table = handle, *prev;
+
+ if (!table || table == &root_table)
+ return;
+
+ if (init_only && table == last_table) {
+ table->init.pc = 0;
+ table->init.range = 0;
+ return;
+ }
+
+ spin_lock(&table_lock);
+ for (prev = &root_table; prev->link && prev->link != table; prev = prev->link)
+ ;
+ if (prev->link) {
+ if (init_only) {
+ table->init.pc = 0;
+ table->init.range = 0;
+ table = NULL;
+ } else {
+ prev->link = table->link;
+ if (!prev->link)
+ last_table = prev;
+ atomic_inc(&removals);
+ }
+ } else
+ table = NULL;
+ spin_unlock(&table_lock);
+
+ if (table) {
+ while (atomic_read(&table->users) || atomic_read(&lookups))
+ msleep(1);
+ kfree(table);
+ }
+}
+
+static uleb128_t
+get_uleb128(const uint8_t **pcur, const uint8_t *end)
+{
+ const uint8_t *cur = *pcur;
+ uleb128_t value;
+ unsigned shift;
+
+ for (shift = 0, value = 0; cur < end; shift += 7) {
+ if (shift + 7 > 8 * sizeof(value) && (*cur & 0x7fU) >= (1U << (8 * sizeof(value) - shift))) {
+ cur = end + 1;
+ break;
+ }
+ value |= (uleb128_t)(*cur & 0x7f) << shift;
+ if (!(*cur++ & 0x80))
+ break;
+ }
+ *pcur = cur;
+ return value;
+}
+
+static sleb128_t
+get_sleb128(const uint8_t **pcur, const uint8_t *end)
+{
+ const uint8_t *cur = *pcur;
+ sleb128_t value;
+ unsigned shift;
+
+ for (shift = 0, value = 0; cur < end; shift += 7) {
+ if (shift + 7 > 8 * sizeof(value) && (*cur & 0x7fU) >= (1U << (8 * sizeof(value) - shift))) {
+ cur = end + 1;
+ break;
+ }
+ value |= (sleb128_t)(*cur & 0x7f) << shift;
+ if (!(*cur & 0x80)) {
+ value |= -(*cur++ & 0x40) << shift;
+ break;
+ }
+ }
+ *pcur = cur;
+ return value;
+}
+
+static unsigned long
+read_pointer(const uint8_t **pLoc, const void *end, signed ptrType)
+{
+ unsigned long value = 0;
+ union {
+ const uint8_t *p8;
+ const uint16_t *p16;
+ const uint32_t *p32;
+ const unsigned long *pul;
+ } ptr;
+
+ if (ptrType < 0 || ptrType == DW_EH_PE_omit)
+ return 0;
+ ptr.p8 = *pLoc;
+ switch(ptrType & DW_EH_PE_FORM) {
+ case DW_EH_PE_data2:
+ if (end < (const void *)(ptr.p16 + 1))
+ return 0;
+ BUILD_BUG_ON(sizeof(uint16_t) > sizeof(unsigned long));
+ value = get_unaligned(ptr.p16++);
+ break;
+ case DW_EH_PE_data4:
+#ifdef CONFIG_64BIT
+ if (end < (const void *)(ptr.p32 + 1))
+ return 0;
+ BUILD_BUG_ON(sizeof(uint32_t) > sizeof(unsigned long));
+ value = get_unaligned(ptr.p32++);
+ break;
+ case DW_EH_PE_data8:
+ BUILD_BUG_ON(sizeof(uint64_t) != sizeof(unsigned long));
+#else
+ BUILD_BUG_ON(sizeof(uint32_t) != sizeof(unsigned long));
+#endif
+ case DW_EH_PE_native:
+ if (end < (const void *)(ptr.pul + 1))
+ return 0;
+ value = get_unaligned(ptr.pul++);
+ break;
+ case DW_EH_PE_leb128:
+ BUILD_BUG_ON(sizeof(uleb128_t) > sizeof(unsigned long));
+ value = ptrType & DW_EH_PE_signed ? get_sleb128(&ptr.p8, end) : get_uleb128(&ptr.p8, end);
+ if ((const void *)ptr.p8 > end)
+ return 0;
+ break;
+ default:
+ return 0;
+ }
+ switch(ptrType & DW_EH_PE_ADJUST) {
+ case DW_EH_PE_abs:
+ break;
+ case DW_EH_PE_pcrel:
+ value += (unsigned long)*pLoc;
+ break;
+ default:
+ return 0;
+ }
+ if ((ptrType & DW_EH_PE_indirect) && __get_user(value, (unsigned long *)value))
+ return 0;
+ *pLoc = ptr.p8;
+ return value;
+}
+
+static signed
+fde_pointer_type(const uint32_t *cie)
+{
+ const uint8_t *ptr = (const uint8_t *)(cie + 2);
+ unsigned version = *ptr;
+
+ if (version != 1)
+ return -1; // unsupported
+ if (*++ptr) {
+ const char *aug;
+ const uint8_t *end = (const uint8_t *)(cie + 1) + *cie;
+ uleb128_t len;
+
+ // check if augmentation size is first (and thus present)
+ if (*ptr != 'z')
+ return -1;
+ // check if augmentation string is nul-terminated
+ if ((ptr = memchr(aug = (const void *)ptr, 0, end - ptr)) == NULL)
+ return -1;
+ ++ptr; // skip terminator
+ get_uleb128(&ptr, end); // skip code alignment
+ get_sleb128(&ptr, end); // skip data alignment
+ version <= 1 ? (void)++ptr : (void)get_uleb128(&ptr, end); // skip return address column
+ len = get_uleb128(&ptr, end); // augmentation length
+ if (ptr + len < ptr || ptr + len > end)
+ return -1;
+ end = ptr + len;
+ while (*++aug) {
+ if (ptr >= end)
+ return -1;
+ switch(*aug) {
+ case 'L':
+ ++ptr;
+ break;
+ case 'P': {
+ signed ptrType = *ptr++;
+
+ if (!read_pointer(&ptr, end, ptrType) || ptr > end)
+ return -1;
+ }
+ break;
+ case 'R':
+ return *ptr;
+ default:
+ return -1;
+ }
+ }
+ }
+ return DW_EH_PE_native|DW_EH_PE_abs;
+}
+
+static int
+advance_loc(unsigned long delta, struct unwind_state *state)
+{
+ state->loc += delta * state->codeAlign;
+ return delta > 0;
+}
+
+static void
+set_rule(uleb128_t reg, enum item_location where, uleb128_t value, struct unwind_state *state)
+{
+ if (reg < ARRAY_SIZE(state->regs)) {
+ state->regs[reg].where = where;
+ state->regs[reg].value = value;
+ }
+}
+
+static int
+processCFI(const uint8_t *start,
+ const uint8_t *end,
+ unsigned long targetLoc,
+ signed ptrType,
+ struct unwind_state *state)
+{
+ union {
+ const uint8_t *p8;
+ const uint16_t *p16;
+ const uint32_t *p32;
+ } ptr;
+ int result = 1;
+
+ if (start != state->cieStart) {
+ state->loc = state->org;
+ result = processCFI(state->cieStart, state->cieEnd, 0, ptrType, state);
+ if (targetLoc == 0 && state->label == NULL)
+ return result;
+ }
+ for (ptr.p8 = start; result && ptr.p8 < end; ) {
+ switch(*ptr.p8 >> 6) {
+ uleb128_t value;
+
+ case 0:
+ switch(*ptr.p8++) {
+ case DW_CFA_nop:
+ break;
+ case DW_CFA_set_loc:
+ if ((state->loc = read_pointer(&ptr.p8, end, ptrType)) == 0)
+ result = 0;
+ break;
+ case DW_CFA_advance_loc1:
+ result = ptr.p8 < end && advance_loc(*ptr.p8++, state);
+ break;
+ case DW_CFA_advance_loc2:
+ result = ptr.p8 <= end + 2 && advance_loc(*ptr.p16++, state);
+ break;
+ case DW_CFA_advance_loc4:
+ result = ptr.p8 <= end + 4 && advance_loc(*ptr.p32++, state);
+ break;
+ case DW_CFA_offset_extended:
+ value = get_uleb128(&ptr.p8, end);
+ set_rule(value, Memory, get_uleb128(&ptr.p8, end), state);
+ break;
+ case DW_CFA_val_offset:
+ value = get_uleb128(&ptr.p8, end);
+ set_rule(value, Value, get_uleb128(&ptr.p8, end), state);
+ break;
+ case DW_CFA_offset_extended_sf:
+ value = get_uleb128(&ptr.p8, end);
+ set_rule(value, Memory, get_sleb128(&ptr.p8, end), state);
+ break;
+ case DW_CFA_val_offset_sf:
+ value = get_uleb128(&ptr.p8, end);
+ set_rule(value, Value, get_sleb128(&ptr.p8, end), state);
+ break;
+ case DW_CFA_restore_extended:
+ case DW_CFA_undefined:
+ case DW_CFA_same_value:
+ set_rule(get_uleb128(&ptr.p8, end), Nowhere, 0, state);
+ break;
+ case DW_CFA_register:
+ value = get_uleb128(&ptr.p8, end);
+ set_rule(value, Register, get_uleb128(&ptr.p8, end), state);
+ break;
+ case DW_CFA_remember_state:
+ if (ptr.p8 == state->label) {
+ state->label = NULL;
+ return 1;
+ }
+ if (state->stackDepth >= MAX_STACK_DEPTH)
+ return 0;
+ state->stack[state->stackDepth++] = ptr.p8;
+ break;
+ case DW_CFA_restore_state:
+ if (state->stackDepth) {
+ const uleb128_t loc = state->loc;
+ const uint8_t *label = state->label;
+
+ state->label = state->stack[state->stackDepth - 1];
+ memcpy(&state->cfa, &badCFA, sizeof(state->cfa));
+ memset(state->regs, 0, sizeof(state->regs));
+ state->stackDepth = 0;
+ result = processCFI(start, end, 0, ptrType, state);
+ state->loc = loc;
+ state->label = label;
+ } else
+ return 0;
+ break;
+ case DW_CFA_def_cfa:
+ state->cfa.reg = get_uleb128(&ptr.p8, end);
+ //nobreak
+ case DW_CFA_def_cfa_offset:
+ state->cfa.offs = get_uleb128(&ptr.p8, end);
+ break;
+ case DW_CFA_def_cfa_sf:
+ state->cfa.reg = get_uleb128(&ptr.p8, end);
+ //nobreak
+ case DW_CFA_def_cfa_offset_sf:
+ state->cfa.offs = get_sleb128(&ptr.p8, end) * state->dataAlign;
+ break;
+ case DW_CFA_def_cfa_register:
+ state->cfa.reg = get_uleb128(&ptr.p8, end);
+ break;
+//todo case DW_CFA_def_cfa_expression:
+//todo case DW_CFA_expression:
+//todo case DW_CFA_val_expression:
+ case DW_CFA_GNU_args_size:
+ get_uleb128(&ptr.p8, end);
+ break;
+ case DW_CFA_GNU_negative_offset_extended:
+ value = get_uleb128(&ptr.p8, end);
+ set_rule(value, Memory, (uleb128_t)0 - get_uleb128(&ptr.p8, end), state);
+ break;
+ case DW_CFA_GNU_window_save:
+ default:
+ result = 0;
+ break;
+ }
+ break;
+ case 1:
+ result = advance_loc(*ptr.p8++ & 0x3f, state);
+ break;
+ case 2:
+ value = *ptr.p8++ & 0x3f;
+ set_rule(value, Memory, get_uleb128(&ptr.p8, end), state);
+ break;
+ case 3:
+ set_rule(*ptr.p8++ & 0x3f, Nowhere, 0, state);
+ break;
+ }
+ if (ptr.p8 > end)
+ result = 0;
+ if (result && targetLoc != 0 && targetLoc < state->loc)
+ return 1;
+ }
+ return result
+ && ptr.p8 == end
+ && (targetLoc == 0
+ || (/*todo While in theory this should apply, gcc in practice omits everything
+ past the function prolog, and hence the location never reaches the
+ end of the function.
+ targetLoc < state->loc &&*/ state->label == NULL));
+}
+
+/*
+ * Unwind to previous to frame. Returns 0 if successful, negative
+ * number in case of an error.
+ */
+int
+unwind(struct unwind_frame_info *frame)
+{
+#define FRAME_REG(r, t) (((t *)frame)[reg_info[r].offs])
+ const uint32_t *fde = NULL, *cie = NULL;
+ const uint8_t *ptr = NULL, *end = NULL;
+ unsigned long startLoc = 0, endLoc = 0, cfa;
+ unsigned i;
+ signed ptrType = -1;
+ uleb128_t retAddrReg = 0;
+ struct unwind_table *table;
+ struct unwind_state state;
+
+ if (UNW_PC(frame) == 0)
+ return -EINVAL;
+ if ((table = find_table(UNW_PC(frame))) != NULL && !(table->size & (sizeof(*fde) - 1))) {
+ unsigned long tableSize = table->size;
+
+ for (fde = (uint32_t *)table->address;
+ tableSize > sizeof(*fde) && tableSize - sizeof(*fde) >= *fde;
+ tableSize -= sizeof(*fde) + *fde, fde += 1 + *fde / sizeof(*fde)) {
+ if (!*fde || (*fde & (sizeof(*fde) - 1)))
+ break;
+ if (!fde[1])
+ continue; // this is a CIE
+ if ((fde[1] & (sizeof(*fde) - 1))
+ || fde[1] > (unsigned long)(fde + 1) - (unsigned long)table->address)
+ continue; // this is not a valid FDE
+ cie = fde + 1 - fde[1] / sizeof(*fde);
+ if (*cie <= sizeof(*cie) + 4
+ || *cie >= fde[1] - sizeof(*fde)
+ || (*cie & (sizeof(*cie) - 1))
+ || cie[1]
+ || (ptrType = fde_pointer_type(cie)) < 0) {
+ cie = NULL; // this is not a (valid) CIE
+ continue;
+ }
+ ptr = (const uint8_t *)(fde + 2);
+ startLoc = read_pointer(&ptr, (const uint8_t *)(fde + 1) + *fde, ptrType);
+ endLoc = startLoc + read_pointer(&ptr,
+ (const uint8_t *)(fde + 1) + *fde,
+ ptrType & DW_EH_PE_indirect
+ ? ptrType
+ : ptrType & (DW_EH_PE_FORM|DW_EH_PE_signed));
+ if (UNW_PC(frame) >= startLoc && UNW_PC(frame) < endLoc)
+ break;
+ cie = NULL;
+ }
+ }
+ if (cie != NULL) {
+ memset(&state, 0, sizeof(state));
+ state.cieEnd = ptr; // keep here temporarily
+ ptr = (const uint8_t *)(cie + 2);
+ end = (const uint8_t *)(cie + 1) + *cie;
+ if ((state.version = *ptr) != 1)
+ cie = NULL; // unsupported version
+ else if (*++ptr) {
+ // check if augmentation size is first (and thus present)
+ if (*ptr == 'z') {
+ // check for ignorable (or already handled) nul-terminated augmentation string
+ while (++ptr < end && *ptr)
+ if (strchr("LPR", *ptr) == NULL)
+ break;
+ }
+ if (ptr >= end || *ptr)
+ cie = NULL;
+ }
+ ++ptr;
+ }
+ if (cie != NULL) {
+ // get code aligment factor
+ state.codeAlign = get_uleb128(&ptr, end);
+ // get data aligment factor
+ state.dataAlign = get_sleb128(&ptr, end);
+ if (state.codeAlign == 0 || state.dataAlign == 0 || ptr >= end)
+ cie = NULL;
+ else {
+ retAddrReg = state.version <= 1 ? *ptr++ : get_uleb128(&ptr, end);
+ // skip augmentation
+ if (((const char *)(cie + 2))[1] == 'z')
+ ptr += get_uleb128(&ptr, end);
+ if (ptr > end
+ || retAddrReg >= ARRAY_SIZE(reg_info)
+ || REG_INVALID(retAddrReg)
+ || reg_info[retAddrReg].width != sizeof(unsigned long))
+ cie = NULL;
+ }
+ }
+ if (cie != NULL) {
+ state.cieStart = ptr;
+ ptr = state.cieEnd;
+ state.cieEnd = end;
+ end = (const uint8_t *)(fde + 1) + *fde;
+ // skip augmentation
+ if (((const char *)(cie + 2))[1] == 'z') {
+ uleb128_t augSize = get_uleb128(&ptr, end);
+
+ if ((ptr += augSize) > end)
+ fde = NULL;
+ }
+ }
+ if (cie == NULL || fde == NULL) {
+#ifdef UNW_FP
+ unsigned long top, bottom;
+#endif
+
+ drop_table(table);
+#ifdef UNW_FP
+ top = STACK_TOP(frame->task);
+ bottom = STACK_BOTTOM(frame->task);
+# if FRAME_RETADDR_OFFSET < 0
+ if (UNW_SP(frame) < top && UNW_FP(frame) <= UNW_SP(frame) && bottom < UNW_FP(frame)
+# else
+ if (UNW_SP(frame) > top && UNW_FP(frame) >= UNW_SP(frame) && bottom > UNW_FP(frame)
+# endif
+ && !((UNW_SP(frame) | UNW_FP(frame)) & (sizeof(unsigned long) - 1))) {
+ unsigned long link;
+
+ if (!__get_user(link, (unsigned long *)(UNW_FP(frame) + FRAME_LINK_OFFSET))
+# if FRAME_RETADDR_OFFSET < 0
+ && link > bottom && link < UNW_FP(frame)
+# else
+ && link > UNW_FP(frame) && link < bottom
+# endif
+ && !(link & (sizeof(link) - 1))
+ && !__get_user(UNW_PC(frame), (unsigned long *)(UNW_FP(frame) + FRAME_RETADDR_OFFSET))) {
+ UNW_SP(frame) = UNW_FP(frame) + FRAME_RETADDR_OFFSET
+# if FRAME_RETADDR_OFFSET < 0
+ -
+# else
+ +
+# endif
+ sizeof(UNW_PC(frame));
+ UNW_FP(frame) = link;
+ return 0;
+ }
+ }
+#endif
+ return -ENXIO;
+ }
+ state.org = startLoc;
+ memcpy(&state.cfa, &badCFA, sizeof(state.cfa));
+ // process instructions
+ if (!processCFI(ptr, end, UNW_PC(frame), ptrType, &state)
+ || state.loc > endLoc
+ || state.regs[retAddrReg].where == Nowhere
+ || state.cfa.reg >= ARRAY_SIZE(reg_info)
+ || reg_info[state.cfa.reg].width != sizeof(unsigned long)
+ || state.cfa.offs % sizeof(unsigned long)) {
+ drop_table(table);
+ return -EIO;
+ }
+ drop_table(table);
+ // update frame
+ cfa = FRAME_REG(state.cfa.reg, unsigned long) + state.cfa.offs;
+ startLoc = min((unsigned long)UNW_SP(frame), cfa);
+ endLoc = max((unsigned long)UNW_SP(frame), cfa);
+#ifndef CONFIG_64BIT
+# define CASES CASE(8); CASE(16); CASE(32)
+#else
+# define CASES CASE(8); CASE(16); CASE(32); CASE(64)
+#endif
+ for (i = 0; i < ARRAY_SIZE(state.regs); ++i) {
+ if (REG_INVALID(i)) {
+ if (state.regs[i].where == Nowhere)
+ continue;
+ return -EIO;
+ }
+ switch(state.regs[i].where) {
+ default:
+ break;
+ case Register:
+ if (state.regs[i].value >= ARRAY_SIZE(reg_info)
+ || REG_INVALID(state.regs[i].value)
+ || reg_info[i].width > reg_info[state.regs[i].value].width)
+ return -EIO;
+ switch(reg_info[state.regs[i].value].width) {
+#define CASE(n) \
+ case sizeof(uint##n##_t): \
+ state.regs[i].value = FRAME_REG(state.regs[i].value, const uint##n##_t); \
+ break
+ CASES;
+#undef CASE
+ default:
+ return -EIO;
+ }
+ break;
+ }
+ }
+ for (i = 0; i < ARRAY_SIZE(state.regs); ++i) {
+ if (REG_INVALID(i))
+ continue;
+ switch(state.regs[i].where) {
+ case Nowhere:
+ if (reg_info[i].width != sizeof(UNW_SP(frame))
+ || &FRAME_REG(i, __typeof__(UNW_SP(frame))) != &UNW_SP(frame))
+ continue;
+ UNW_SP(frame) = cfa;
+ break;
+ case Register:
+ switch(reg_info[i].width) {
+#define CASE(n) case sizeof(uint##n##_t): \
+ FRAME_REG(i, uint##n##_t) = state.regs[i].value; \
+ break
+ CASES;
+#undef CASE
+ default:
+ return -EIO;
+ }
+ break;
+ case Value:
+ if (reg_info[i].width != sizeof(unsigned long))
+ return -EIO;
+ FRAME_REG(i, unsigned long) = cfa + state.regs[i].value * state.dataAlign;
+ break;
+ case Memory: {
+ unsigned long addr = cfa + state.regs[i].value * state.dataAlign;
+
+ if ((state.regs[i].value * state.dataAlign) % sizeof(unsigned long)
+ || addr < startLoc
+ || addr + sizeof(unsigned long) < addr
+ || addr + sizeof(unsigned long) > endLoc)
+ return -EIO;
+ switch(reg_info[i].width) {
+#define CASE(n) case sizeof(uint##n##_t): \
+ __get_user(FRAME_REG(i, uint##n##_t), (uint##n##_t *)addr); \
+ break
+ CASES;
+#undef CASE
+ default:
+ return -EIO;
+ }
+ }
+ break;
+ }
+ }
+ return 0;
+#undef CASES
+#undef FRAME_REG
+}
+EXPORT_SYMBOL_GPL(unwind);
+
+int unwind_init_frame_info(struct unwind_frame_info *info, struct task_struct *tsk, /*const*/ struct pt_regs *regs)
+{
+ info->task = tsk;
+ arch_unw_init_frame_info(info, regs);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(unwind_init_frame_info);
+
+/*
+ * Prepare to unwind a blocked task.
+ */
+int unwind_init_blocked(struct unwind_frame_info *info, struct task_struct *tsk)
+{
+ info->task = tsk;
+ arch_unw_init_blocked(info);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(unwind_init_blocked);
+
+/*
+ * Prepare to unwind the currently running thread.
+ */
+int unwind_init_running(struct unwind_frame_info *info,
+ asmlinkage void (*callback)(struct unwind_frame_info *, void *arg),
+ void *arg)
+{
+ info->task = current;
+ arch_unwind_init_running(info, callback, arg);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(unwind_init_running);
+
+/*
+ * Unwind until the return pointer is in user-land (or until an error
+ * occurs). Returns 0 if successful, negative number in case of
+ * error.
+ */
+int unwind_to_user(struct unwind_frame_info *info)
+{
+ while (!arch_unw_user_mode(info)) {
+ int err = unwind(info);
+
+ if (err < 0)
+ return err;
+ }
+ return 0;
+}
+EXPORT_SYMBOL_GPL(unwind_to_user);
--- linux-2.6.17-rc4/lib/Kconfig.debug 2006-05-16 15:15:49.000000000 +0200
+++ 2.6.17-rc4-unwind-generic/lib/Kconfig.debug 2006-05-16 15:16:46.000000000 +0200
@@ -188,7 +188,7 @@ config FRAME_POINTER

config UNWIND_INFO
bool "Compile the kernel with frame unwind information"
- depends on !IA64
+ depends on !IA64 && !PARISC
depends on !MODULES || !(MIPS || PARISC || PPC || SUPERH || SPARC64 || V850)
help
If you say Y here the resulting kernel image will be slightly larger
@@ -196,6 +196,14 @@ config UNWIND_INFO
If you don't debug the kernel, you can say N, but we may not be able
to solve problems without frame unwind information or frame pointers.

+config STACK_UNWIND
+ bool "Stack unwind support"
+ depends on UNWIND_INFO
+ depends on n
+ help
+ This enables more precise stack traces, omitting all unrelated
+ occurrences of pointers into kernel code from the dump.
+
config FORCED_INLINING
bool "Force gcc to inline functions marked 'inline'"
depends on DEBUG_KERNEL

-
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