kernel-fxtec-pro1x/arch/sh/kernel/dwarf.c
Matt Fleming b344e24a8e sh: unwinder: Introduce UNWINDER_BUG() and UNWINDER_BUG_ON()
We can't assume that if we execute the unwinder code and the unwinder
was already running that it has faulted. Clearly two kernel threads can
invoke the unwinder at the same time and may be running simultaneously.

The previous approach used BUG() and BUG_ON() in the unwinder code to
detect whether the unwinder was incapable of unwinding the stack, and
that the next available unwinder should be used instead. A better
approach is to explicitly invoke a trap handler to switch unwinders when
the current unwinder cannot continue.

Signed-off-by: Matt Fleming <matt@console-pimps.org>
2009-08-21 13:02:44 +01:00

959 lines
23 KiB
C

/*
* Copyright (C) 2009 Matt Fleming <matt@console-pimps.org>
*
* 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.
*
* This is an implementation of a DWARF unwinder. Its main purpose is
* for generating stacktrace information. Based on the DWARF 3
* specification from http://www.dwarfstd.org.
*
* TODO:
* - DWARF64 doesn't work.
* - Registers with DWARF_VAL_OFFSET rules aren't handled properly.
*/
/* #define DEBUG */
#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/list.h>
#include <linux/mempool.h>
#include <linux/mm.h>
#include <asm/dwarf.h>
#include <asm/unwinder.h>
#include <asm/sections.h>
#include <asm/unaligned.h>
#include <asm/dwarf.h>
#include <asm/stacktrace.h>
/* Reserve enough memory for two stack frames */
#define DWARF_FRAME_MIN_REQ 2
/* ... with 4 registers per frame. */
#define DWARF_REG_MIN_REQ (DWARF_FRAME_MIN_REQ * 4)
static struct kmem_cache *dwarf_frame_cachep;
static mempool_t *dwarf_frame_pool;
static struct kmem_cache *dwarf_reg_cachep;
static mempool_t *dwarf_reg_pool;
static LIST_HEAD(dwarf_cie_list);
static DEFINE_SPINLOCK(dwarf_cie_lock);
static LIST_HEAD(dwarf_fde_list);
static DEFINE_SPINLOCK(dwarf_fde_lock);
static struct dwarf_cie *cached_cie;
/**
* dwarf_frame_alloc_reg - allocate memory for a DWARF register
* @frame: the DWARF frame whose list of registers we insert on
* @reg_num: the register number
*
* Allocate space for, and initialise, a dwarf reg from
* dwarf_reg_pool and insert it onto the (unsorted) linked-list of
* dwarf registers for @frame.
*
* Return the initialised DWARF reg.
*/
static struct dwarf_reg *dwarf_frame_alloc_reg(struct dwarf_frame *frame,
unsigned int reg_num)
{
struct dwarf_reg *reg;
reg = mempool_alloc(dwarf_reg_pool, GFP_ATOMIC);
if (!reg) {
printk(KERN_WARNING "Unable to allocate a DWARF register\n");
/*
* Let's just bomb hard here, we have no way to
* gracefully recover.
*/
UNWINDER_BUG();
}
reg->number = reg_num;
reg->addr = 0;
reg->flags = 0;
list_add(&reg->link, &frame->reg_list);
return reg;
}
static void dwarf_frame_free_regs(struct dwarf_frame *frame)
{
struct dwarf_reg *reg, *n;
list_for_each_entry_safe(reg, n, &frame->reg_list, link) {
list_del(&reg->link);
mempool_free(reg, dwarf_reg_pool);
}
}
/**
* dwarf_frame_reg - return a DWARF register
* @frame: the DWARF frame to search in for @reg_num
* @reg_num: the register number to search for
*
* Lookup and return the dwarf reg @reg_num for this frame. Return
* NULL if @reg_num is an register invalid number.
*/
static struct dwarf_reg *dwarf_frame_reg(struct dwarf_frame *frame,
unsigned int reg_num)
{
struct dwarf_reg *reg;
list_for_each_entry(reg, &frame->reg_list, link) {
if (reg->number == reg_num)
return reg;
}
return NULL;
}
/**
* dwarf_read_addr - read dwarf data
* @src: source address of data
* @dst: destination address to store the data to
*
* Read 'n' bytes from @src, where 'n' is the size of an address on
* the native machine. We return the number of bytes read, which
* should always be 'n'. We also have to be careful when reading
* from @src and writing to @dst, because they can be arbitrarily
* aligned. Return 'n' - the number of bytes read.
*/
static inline int dwarf_read_addr(unsigned long *src, unsigned long *dst)
{
u32 val = get_unaligned(src);
put_unaligned(val, dst);
return sizeof(unsigned long *);
}
/**
* dwarf_read_uleb128 - read unsigned LEB128 data
* @addr: the address where the ULEB128 data is stored
* @ret: address to store the result
*
* Decode an unsigned LEB128 encoded datum. The algorithm is taken
* from Appendix C of the DWARF 3 spec. For information on the
* encodings refer to section "7.6 - Variable Length Data". Return
* the number of bytes read.
*/
static inline unsigned long dwarf_read_uleb128(char *addr, unsigned int *ret)
{
unsigned int result;
unsigned char byte;
int shift, count;
result = 0;
shift = 0;
count = 0;
while (1) {
byte = __raw_readb(addr);
addr++;
count++;
result |= (byte & 0x7f) << shift;
shift += 7;
if (!(byte & 0x80))
break;
}
*ret = result;
return count;
}
/**
* dwarf_read_leb128 - read signed LEB128 data
* @addr: the address of the LEB128 encoded data
* @ret: address to store the result
*
* Decode signed LEB128 data. The algorithm is taken from Appendix
* C of the DWARF 3 spec. Return the number of bytes read.
*/
static inline unsigned long dwarf_read_leb128(char *addr, int *ret)
{
unsigned char byte;
int result, shift;
int num_bits;
int count;
result = 0;
shift = 0;
count = 0;
while (1) {
byte = __raw_readb(addr);
addr++;
result |= (byte & 0x7f) << shift;
shift += 7;
count++;
if (!(byte & 0x80))
break;
}
/* The number of bits in a signed integer. */
num_bits = 8 * sizeof(result);
if ((shift < num_bits) && (byte & 0x40))
result |= (-1 << shift);
*ret = result;
return count;
}
/**
* dwarf_read_encoded_value - return the decoded value at @addr
* @addr: the address of the encoded value
* @val: where to write the decoded value
* @encoding: the encoding with which we can decode @addr
*
* GCC emits encoded address in the .eh_frame FDE entries. Decode
* the value at @addr using @encoding. The decoded value is written
* to @val and the number of bytes read is returned.
*/
static int dwarf_read_encoded_value(char *addr, unsigned long *val,
char encoding)
{
unsigned long decoded_addr = 0;
int count = 0;
switch (encoding & 0x70) {
case DW_EH_PE_absptr:
break;
case DW_EH_PE_pcrel:
decoded_addr = (unsigned long)addr;
break;
default:
pr_debug("encoding=0x%x\n", (encoding & 0x70));
UNWINDER_BUG();
}
if ((encoding & 0x07) == 0x00)
encoding |= DW_EH_PE_udata4;
switch (encoding & 0x0f) {
case DW_EH_PE_sdata4:
case DW_EH_PE_udata4:
count += 4;
decoded_addr += get_unaligned((u32 *)addr);
__raw_writel(decoded_addr, val);
break;
default:
pr_debug("encoding=0x%x\n", encoding);
UNWINDER_BUG();
}
return count;
}
/**
* dwarf_entry_len - return the length of an FDE or CIE
* @addr: the address of the entry
* @len: the length of the entry
*
* Read the initial_length field of the entry and store the size of
* the entry in @len. We return the number of bytes read. Return a
* count of 0 on error.
*/
static inline int dwarf_entry_len(char *addr, unsigned long *len)
{
u32 initial_len;
int count;
initial_len = get_unaligned((u32 *)addr);
count = 4;
/*
* An initial length field value in the range DW_LEN_EXT_LO -
* DW_LEN_EXT_HI indicates an extension, and should not be
* interpreted as a length. The only extension that we currently
* understand is the use of DWARF64 addresses.
*/
if (initial_len >= DW_EXT_LO && initial_len <= DW_EXT_HI) {
/*
* The 64-bit length field immediately follows the
* compulsory 32-bit length field.
*/
if (initial_len == DW_EXT_DWARF64) {
*len = get_unaligned((u64 *)addr + 4);
count = 12;
} else {
printk(KERN_WARNING "Unknown DWARF extension\n");
count = 0;
}
} else
*len = initial_len;
return count;
}
/**
* dwarf_lookup_cie - locate the cie
* @cie_ptr: pointer to help with lookup
*/
static struct dwarf_cie *dwarf_lookup_cie(unsigned long cie_ptr)
{
struct dwarf_cie *cie;
unsigned long flags;
spin_lock_irqsave(&dwarf_cie_lock, flags);
/*
* We've cached the last CIE we looked up because chances are
* that the FDE wants this CIE.
*/
if (cached_cie && cached_cie->cie_pointer == cie_ptr) {
cie = cached_cie;
goto out;
}
list_for_each_entry(cie, &dwarf_cie_list, link) {
if (cie->cie_pointer == cie_ptr) {
cached_cie = cie;
break;
}
}
/* Couldn't find the entry in the list. */
if (&cie->link == &dwarf_cie_list)
cie = NULL;
out:
spin_unlock_irqrestore(&dwarf_cie_lock, flags);
return cie;
}
/**
* dwarf_lookup_fde - locate the FDE that covers pc
* @pc: the program counter
*/
struct dwarf_fde *dwarf_lookup_fde(unsigned long pc)
{
struct dwarf_fde *fde;
unsigned long flags;
spin_lock_irqsave(&dwarf_fde_lock, flags);
list_for_each_entry(fde, &dwarf_fde_list, link) {
unsigned long start, end;
start = fde->initial_location;
end = fde->initial_location + fde->address_range;
if (pc >= start && pc < end)
break;
}
/* Couldn't find the entry in the list. */
if (&fde->link == &dwarf_fde_list)
fde = NULL;
spin_unlock_irqrestore(&dwarf_fde_lock, flags);
return fde;
}
/**
* dwarf_cfa_execute_insns - execute instructions to calculate a CFA
* @insn_start: address of the first instruction
* @insn_end: address of the last instruction
* @cie: the CIE for this function
* @fde: the FDE for this function
* @frame: the instructions calculate the CFA for this frame
* @pc: the program counter of the address we're interested in
*
* Execute the Call Frame instruction sequence starting at
* @insn_start and ending at @insn_end. The instructions describe
* how to calculate the Canonical Frame Address of a stackframe.
* Store the results in @frame.
*/
static int dwarf_cfa_execute_insns(unsigned char *insn_start,
unsigned char *insn_end,
struct dwarf_cie *cie,
struct dwarf_fde *fde,
struct dwarf_frame *frame,
unsigned long pc)
{
unsigned char insn;
unsigned char *current_insn;
unsigned int count, delta, reg, expr_len, offset;
struct dwarf_reg *regp;
current_insn = insn_start;
while (current_insn < insn_end && frame->pc <= pc) {
insn = __raw_readb(current_insn++);
/*
* Firstly, handle the opcodes that embed their operands
* in the instructions.
*/
switch (DW_CFA_opcode(insn)) {
case DW_CFA_advance_loc:
delta = DW_CFA_operand(insn);
delta *= cie->code_alignment_factor;
frame->pc += delta;
continue;
/* NOTREACHED */
case DW_CFA_offset:
reg = DW_CFA_operand(insn);
count = dwarf_read_uleb128(current_insn, &offset);
current_insn += count;
offset *= cie->data_alignment_factor;
regp = dwarf_frame_alloc_reg(frame, reg);
regp->addr = offset;
regp->flags |= DWARF_REG_OFFSET;
continue;
/* NOTREACHED */
case DW_CFA_restore:
reg = DW_CFA_operand(insn);
continue;
/* NOTREACHED */
}
/*
* Secondly, handle the opcodes that don't embed their
* operands in the instruction.
*/
switch (insn) {
case DW_CFA_nop:
continue;
case DW_CFA_advance_loc1:
delta = *current_insn++;
frame->pc += delta * cie->code_alignment_factor;
break;
case DW_CFA_advance_loc2:
delta = get_unaligned((u16 *)current_insn);
current_insn += 2;
frame->pc += delta * cie->code_alignment_factor;
break;
case DW_CFA_advance_loc4:
delta = get_unaligned((u32 *)current_insn);
current_insn += 4;
frame->pc += delta * cie->code_alignment_factor;
break;
case DW_CFA_offset_extended:
count = dwarf_read_uleb128(current_insn, &reg);
current_insn += count;
count = dwarf_read_uleb128(current_insn, &offset);
current_insn += count;
offset *= cie->data_alignment_factor;
break;
case DW_CFA_restore_extended:
count = dwarf_read_uleb128(current_insn, &reg);
current_insn += count;
break;
case DW_CFA_undefined:
count = dwarf_read_uleb128(current_insn, &reg);
current_insn += count;
break;
case DW_CFA_def_cfa:
count = dwarf_read_uleb128(current_insn,
&frame->cfa_register);
current_insn += count;
count = dwarf_read_uleb128(current_insn,
&frame->cfa_offset);
current_insn += count;
frame->flags |= DWARF_FRAME_CFA_REG_OFFSET;
break;
case DW_CFA_def_cfa_register:
count = dwarf_read_uleb128(current_insn,
&frame->cfa_register);
current_insn += count;
frame->flags |= DWARF_FRAME_CFA_REG_OFFSET;
break;
case DW_CFA_def_cfa_offset:
count = dwarf_read_uleb128(current_insn, &offset);
current_insn += count;
frame->cfa_offset = offset;
break;
case DW_CFA_def_cfa_expression:
count = dwarf_read_uleb128(current_insn, &expr_len);
current_insn += count;
frame->cfa_expr = current_insn;
frame->cfa_expr_len = expr_len;
current_insn += expr_len;
frame->flags |= DWARF_FRAME_CFA_REG_EXP;
break;
case DW_CFA_offset_extended_sf:
count = dwarf_read_uleb128(current_insn, &reg);
current_insn += count;
count = dwarf_read_leb128(current_insn, &offset);
current_insn += count;
offset *= cie->data_alignment_factor;
regp = dwarf_frame_alloc_reg(frame, reg);
regp->flags |= DWARF_REG_OFFSET;
regp->addr = offset;
break;
case DW_CFA_val_offset:
count = dwarf_read_uleb128(current_insn, &reg);
current_insn += count;
count = dwarf_read_leb128(current_insn, &offset);
offset *= cie->data_alignment_factor;
regp = dwarf_frame_alloc_reg(frame, reg);
regp->flags |= DWARF_VAL_OFFSET;
regp->addr = offset;
break;
case DW_CFA_GNU_args_size:
count = dwarf_read_uleb128(current_insn, &offset);
current_insn += count;
break;
case DW_CFA_GNU_negative_offset_extended:
count = dwarf_read_uleb128(current_insn, &reg);
current_insn += count;
count = dwarf_read_uleb128(current_insn, &offset);
offset *= cie->data_alignment_factor;
regp = dwarf_frame_alloc_reg(frame, reg);
regp->flags |= DWARF_REG_OFFSET;
regp->addr = -offset;
break;
default:
pr_debug("unhandled DWARF instruction 0x%x\n", insn);
UNWINDER_BUG();
break;
}
}
return 0;
}
/**
* dwarf_unwind_stack - recursively unwind the stack
* @pc: address of the function to unwind
* @prev: struct dwarf_frame of the previous stackframe on the callstack
*
* Return a struct dwarf_frame representing the most recent frame
* on the callstack. Each of the lower (older) stack frames are
* linked via the "prev" member.
*/
struct dwarf_frame * dwarf_unwind_stack(unsigned long pc,
struct dwarf_frame *prev)
{
struct dwarf_frame *frame;
struct dwarf_cie *cie;
struct dwarf_fde *fde;
struct dwarf_reg *reg;
unsigned long addr;
/*
* If this is the first invocation of this recursive function we
* need get the contents of a physical register to get the CFA
* in order to begin the virtual unwinding of the stack.
*
* NOTE: the return address is guaranteed to be setup by the
* time this function makes its first function call.
*/
if (!pc && !prev)
pc = (unsigned long)current_text_addr();
frame = mempool_alloc(dwarf_frame_pool, GFP_ATOMIC);
if (!frame) {
printk(KERN_ERR "Unable to allocate a dwarf frame\n");
UNWINDER_BUG();
}
INIT_LIST_HEAD(&frame->reg_list);
frame->flags = 0;
frame->prev = prev;
frame->return_addr = 0;
fde = dwarf_lookup_fde(pc);
if (!fde) {
/*
* This is our normal exit path - the one that stops the
* recursion. There's two reasons why we might exit
* here,
*
* a) pc has no asscociated DWARF frame info and so
* we don't know how to unwind this frame. This is
* usually the case when we're trying to unwind a
* frame that was called from some assembly code
* that has no DWARF info, e.g. syscalls.
*
* b) the DEBUG info for pc is bogus. There's
* really no way to distinguish this case from the
* case above, which sucks because we could print a
* warning here.
*/
goto bail;
}
cie = dwarf_lookup_cie(fde->cie_pointer);
frame->pc = fde->initial_location;
/* CIE initial instructions */
dwarf_cfa_execute_insns(cie->initial_instructions,
cie->instructions_end, cie, fde,
frame, pc);
/* FDE instructions */
dwarf_cfa_execute_insns(fde->instructions, fde->end, cie,
fde, frame, pc);
/* Calculate the CFA */
switch (frame->flags) {
case DWARF_FRAME_CFA_REG_OFFSET:
if (prev) {
reg = dwarf_frame_reg(prev, frame->cfa_register);
UNWINDER_BUG_ON(!reg);
UNWINDER_BUG_ON(reg->flags != DWARF_REG_OFFSET);
addr = prev->cfa + reg->addr;
frame->cfa = __raw_readl(addr);
} else {
/*
* Again, this is the first invocation of this
* recurisve function. We need to physically
* read the contents of a register in order to
* get the Canonical Frame Address for this
* function.
*/
frame->cfa = dwarf_read_arch_reg(frame->cfa_register);
}
frame->cfa += frame->cfa_offset;
break;
default:
UNWINDER_BUG();
}
/* If we haven't seen the return address reg, we're screwed. */
reg = dwarf_frame_reg(frame, DWARF_ARCH_RA_REG);
UNWINDER_BUG_ON(!reg);
UNWINDER_BUG_ON(reg->flags != DWARF_REG_OFFSET);
addr = frame->cfa + reg->addr;
frame->return_addr = __raw_readl(addr);
return frame;
bail:
dwarf_frame_free_regs(frame);
mempool_free(frame, dwarf_frame_pool);
return NULL;
}
static int dwarf_parse_cie(void *entry, void *p, unsigned long len,
unsigned char *end)
{
struct dwarf_cie *cie;
unsigned long flags;
int count;
cie = kzalloc(sizeof(*cie), GFP_KERNEL);
if (!cie)
return -ENOMEM;
cie->length = len;
/*
* Record the offset into the .eh_frame section
* for this CIE. It allows this CIE to be
* quickly and easily looked up from the
* corresponding FDE.
*/
cie->cie_pointer = (unsigned long)entry;
cie->version = *(char *)p++;
UNWINDER_BUG_ON(cie->version != 1);
cie->augmentation = p;
p += strlen(cie->augmentation) + 1;
count = dwarf_read_uleb128(p, &cie->code_alignment_factor);
p += count;
count = dwarf_read_leb128(p, &cie->data_alignment_factor);
p += count;
/*
* Which column in the rule table contains the
* return address?
*/
if (cie->version == 1) {
cie->return_address_reg = __raw_readb(p);
p++;
} else {
count = dwarf_read_uleb128(p, &cie->return_address_reg);
p += count;
}
if (cie->augmentation[0] == 'z') {
unsigned int length, count;
cie->flags |= DWARF_CIE_Z_AUGMENTATION;
count = dwarf_read_uleb128(p, &length);
p += count;
UNWINDER_BUG_ON((unsigned char *)p > end);
cie->initial_instructions = p + length;
cie->augmentation++;
}
while (*cie->augmentation) {
/*
* "L" indicates a byte showing how the
* LSDA pointer is encoded. Skip it.
*/
if (*cie->augmentation == 'L') {
p++;
cie->augmentation++;
} else if (*cie->augmentation == 'R') {
/*
* "R" indicates a byte showing
* how FDE addresses are
* encoded.
*/
cie->encoding = *(char *)p++;
cie->augmentation++;
} else if (*cie->augmentation == 'P') {
/*
* "R" indicates a personality
* routine in the CIE
* augmentation.
*/
UNWINDER_BUG();
} else if (*cie->augmentation == 'S') {
UNWINDER_BUG();
} else {
/*
* Unknown augmentation. Assume
* 'z' augmentation.
*/
p = cie->initial_instructions;
UNWINDER_BUG_ON(!p);
break;
}
}
cie->initial_instructions = p;
cie->instructions_end = end;
/* Add to list */
spin_lock_irqsave(&dwarf_cie_lock, flags);
list_add_tail(&cie->link, &dwarf_cie_list);
spin_unlock_irqrestore(&dwarf_cie_lock, flags);
return 0;
}
static int dwarf_parse_fde(void *entry, u32 entry_type,
void *start, unsigned long len)
{
struct dwarf_fde *fde;
struct dwarf_cie *cie;
unsigned long flags;
int count;
void *p = start;
fde = kzalloc(sizeof(*fde), GFP_KERNEL);
if (!fde)
return -ENOMEM;
fde->length = len;
/*
* In a .eh_frame section the CIE pointer is the
* delta between the address within the FDE
*/
fde->cie_pointer = (unsigned long)(p - entry_type - 4);
cie = dwarf_lookup_cie(fde->cie_pointer);
fde->cie = cie;
if (cie->encoding)
count = dwarf_read_encoded_value(p, &fde->initial_location,
cie->encoding);
else
count = dwarf_read_addr(p, &fde->initial_location);
p += count;
if (cie->encoding)
count = dwarf_read_encoded_value(p, &fde->address_range,
cie->encoding & 0x0f);
else
count = dwarf_read_addr(p, &fde->address_range);
p += count;
if (fde->cie->flags & DWARF_CIE_Z_AUGMENTATION) {
unsigned int length;
count = dwarf_read_uleb128(p, &length);
p += count + length;
}
/* Call frame instructions. */
fde->instructions = p;
fde->end = start + len;
/* Add to list. */
spin_lock_irqsave(&dwarf_fde_lock, flags);
list_add_tail(&fde->link, &dwarf_fde_list);
spin_unlock_irqrestore(&dwarf_fde_lock, flags);
return 0;
}
static void dwarf_unwinder_dump(struct task_struct *task,
struct pt_regs *regs,
unsigned long *sp,
const struct stacktrace_ops *ops,
void *data)
{
struct dwarf_frame *frame, *_frame;
unsigned long return_addr;
_frame = NULL;
return_addr = 0;
while (1) {
frame = dwarf_unwind_stack(return_addr, _frame);
if (_frame) {
dwarf_frame_free_regs(_frame);
mempool_free(_frame, dwarf_frame_pool);
}
_frame = frame;
if (!frame || !frame->return_addr)
break;
return_addr = frame->return_addr;
ops->address(data, return_addr, 1);
}
}
static struct unwinder dwarf_unwinder = {
.name = "dwarf-unwinder",
.dump = dwarf_unwinder_dump,
.rating = 150,
};
static void dwarf_unwinder_cleanup(void)
{
struct dwarf_cie *cie;
struct dwarf_fde *fde;
/*
* Deallocate all the memory allocated for the DWARF unwinder.
* Traverse all the FDE/CIE lists and remove and free all the
* memory associated with those data structures.
*/
list_for_each_entry(cie, &dwarf_cie_list, link)
kfree(cie);
list_for_each_entry(fde, &dwarf_fde_list, link)
kfree(fde);
kmem_cache_destroy(dwarf_reg_cachep);
kmem_cache_destroy(dwarf_frame_cachep);
}
/**
* dwarf_unwinder_init - initialise the dwarf unwinder
*
* Build the data structures describing the .dwarf_frame section to
* make it easier to lookup CIE and FDE entries. Because the
* .eh_frame section is packed as tightly as possible it is not
* easy to lookup the FDE for a given PC, so we build a list of FDE
* and CIE entries that make it easier.
*/
static int __init dwarf_unwinder_init(void)
{
u32 entry_type;
void *p, *entry;
int count, err;
unsigned long len;
unsigned int c_entries, f_entries;
unsigned char *end;
INIT_LIST_HEAD(&dwarf_cie_list);
INIT_LIST_HEAD(&dwarf_fde_list);
c_entries = 0;
f_entries = 0;
entry = &__start_eh_frame;
dwarf_frame_cachep = kmem_cache_create("dwarf_frames",
sizeof(struct dwarf_frame), 0, SLAB_PANIC, NULL);
dwarf_reg_cachep = kmem_cache_create("dwarf_regs",
sizeof(struct dwarf_reg), 0, SLAB_PANIC, NULL);
dwarf_frame_pool = mempool_create(DWARF_FRAME_MIN_REQ,
mempool_alloc_slab,
mempool_free_slab,
dwarf_frame_cachep);
dwarf_reg_pool = mempool_create(DWARF_REG_MIN_REQ,
mempool_alloc_slab,
mempool_free_slab,
dwarf_reg_cachep);
while ((char *)entry < __stop_eh_frame) {
p = entry;
count = dwarf_entry_len(p, &len);
if (count == 0) {
/*
* We read a bogus length field value. There is
* nothing we can do here apart from disabling
* the DWARF unwinder. We can't even skip this
* entry and move to the next one because 'len'
* tells us where our next entry is.
*/
goto out;
} else
p += count;
/* initial length does not include itself */
end = p + len;
entry_type = get_unaligned((u32 *)p);
p += 4;
if (entry_type == DW_EH_FRAME_CIE) {
err = dwarf_parse_cie(entry, p, len, end);
if (err < 0)
goto out;
else
c_entries++;
} else {
err = dwarf_parse_fde(entry, entry_type, p, len);
if (err < 0)
goto out;
else
f_entries++;
}
entry = (char *)entry + len + 4;
}
printk(KERN_INFO "DWARF unwinder initialised: read %u CIEs, %u FDEs\n",
c_entries, f_entries);
err = unwinder_register(&dwarf_unwinder);
if (err)
goto out;
return 0;
out:
printk(KERN_ERR "Failed to initialise DWARF unwinder: %d\n", err);
dwarf_unwinder_cleanup();
return -EINVAL;
}
early_initcall(dwarf_unwinder_init);