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Merge branch 'sh/dwarf-unwinder'
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Conflicts:
	arch/sh/kernel/dwarf.c
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Paul Mundt committed Oct 11, 2009
2 parents 3d4e0cf + 5ab78ff commit 8ec006c
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Showing 3 changed files with 183 additions and 50 deletions.
16 changes: 16 additions & 0 deletions arch/sh/include/asm/dwarf.h
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Original file line number Diff line number Diff line change
Expand Up @@ -241,6 +241,12 @@ struct dwarf_cie {

unsigned long flags;
#define DWARF_CIE_Z_AUGMENTATION (1 << 0)

/*
* 'mod' will be non-NULL if this CIE came from a module's
* .eh_frame section.
*/
struct module *mod;
};

/**
Expand All @@ -255,6 +261,12 @@ struct dwarf_fde {
unsigned char *instructions;
unsigned char *end;
struct list_head link;

/*
* 'mod' will be non-NULL if this FDE came from a module's
* .eh_frame section.
*/
struct module *mod;
};

/**
Expand Down Expand Up @@ -364,6 +376,10 @@ static inline unsigned int DW_CFA_operand(unsigned long insn)

extern struct dwarf_frame *dwarf_unwind_stack(unsigned long,
struct dwarf_frame *);
extern void dwarf_free_frame(struct dwarf_frame *);
extern int dwarf_parse_section(char *, char *, struct module *);
extern void dwarf_module_unload(struct module *);

#endif /* !__ASSEMBLY__ */

#define CFI_STARTPROC .cfi_startproc
Expand Down
185 changes: 135 additions & 50 deletions arch/sh/kernel/dwarf.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -529,7 +529,18 @@ static int dwarf_cfa_execute_insns(unsigned char *insn_start,
}

/**
* dwarf_unwind_stack - recursively unwind the stack
* dwarf_free_frame - free the memory allocated for @frame
* @frame: the frame to free
*/
void dwarf_free_frame(struct dwarf_frame *frame)
{
dwarf_frame_free_regs(frame);
mempool_free(frame, dwarf_frame_pool);
}

/**
* dwarf_unwind_stack - unwind the stack
*
* @pc: address of the function to unwind
* @prev: struct dwarf_frame of the previous stackframe on the callstack
*
Expand All @@ -547,9 +558,9 @@ struct dwarf_frame * dwarf_unwind_stack(unsigned long pc,
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.
* If we're starting at the top of the stack 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.
Expand All @@ -571,9 +582,8 @@ struct dwarf_frame * dwarf_unwind_stack(unsigned long pc,
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,
* This is our normal exit path. There are 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
Expand Down Expand Up @@ -615,10 +625,10 @@ struct dwarf_frame * dwarf_unwind_stack(unsigned long pc,

} 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
* Again, we're starting from the top of the
* stack. 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);
Expand Down Expand Up @@ -648,13 +658,12 @@ struct dwarf_frame * dwarf_unwind_stack(unsigned long pc,
return frame;

bail:
dwarf_frame_free_regs(frame);
mempool_free(frame, dwarf_frame_pool);
dwarf_free_frame(frame);
return NULL;
}

static int dwarf_parse_cie(void *entry, void *p, unsigned long len,
unsigned char *end)
unsigned char *end, struct module *mod)
{
struct dwarf_cie *cie;
unsigned long flags;
Expand Down Expand Up @@ -750,6 +759,8 @@ static int dwarf_parse_cie(void *entry, void *p, unsigned long len,
cie->initial_instructions = p;
cie->instructions_end = end;

cie->mod = mod;

/* Add to list */
spin_lock_irqsave(&dwarf_cie_lock, flags);
list_add_tail(&cie->link, &dwarf_cie_list);
Expand All @@ -760,7 +771,7 @@ static int dwarf_parse_cie(void *entry, void *p, unsigned long len,

static int dwarf_parse_fde(void *entry, u32 entry_type,
void *start, unsigned long len,
unsigned char *end)
unsigned char *end, struct module *mod)
{
struct dwarf_fde *fde;
struct dwarf_cie *cie;
Expand Down Expand Up @@ -809,6 +820,8 @@ static int dwarf_parse_fde(void *entry, u32 entry_type,
fde->instructions = p;
fde->end = end;

fde->mod = mod;

/* Add to list. */
spin_lock_irqsave(&dwarf_fde_lock, flags);
list_add_tail(&fde->link, &dwarf_fde_list);
Expand All @@ -832,10 +845,8 @@ static void dwarf_unwinder_dump(struct task_struct *task,
while (1) {
frame = dwarf_unwind_stack(return_addr, _frame);

if (_frame) {
dwarf_frame_free_regs(_frame);
mempool_free(_frame, dwarf_frame_pool);
}
if (_frame)
dwarf_free_frame(_frame);

_frame = frame;

Expand All @@ -845,6 +856,9 @@ static void dwarf_unwinder_dump(struct task_struct *task,
return_addr = frame->return_addr;
ops->address(data, return_addr, 1);
}

if (frame)
dwarf_free_frame(frame);
}

static struct unwinder dwarf_unwinder = {
Expand Down Expand Up @@ -874,48 +888,28 @@ static void dwarf_unwinder_cleanup(void)
}

/**
* dwarf_unwinder_init - initialise the dwarf unwinder
* dwarf_parse_section - parse DWARF section
* @eh_frame_start: start address of the .eh_frame section
* @eh_frame_end: end address of the .eh_frame section
* @mod: the kernel module containing the .eh_frame section
*
* 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.
* Parse the information in a .eh_frame section.
*/
static int __init dwarf_unwinder_init(void)
int dwarf_parse_section(char *eh_frame_start, char *eh_frame_end,
struct module *mod)
{
u32 entry_type;
void *p, *entry;
int count, err = 0;
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 | SLAB_HWCACHE_ALIGN | SLAB_NOTRACK, NULL);

dwarf_reg_cachep = kmem_cache_create("dwarf_regs",
sizeof(struct dwarf_reg), 0,
SLAB_PANIC | SLAB_HWCACHE_ALIGN | SLAB_NOTRACK, NULL);

dwarf_frame_pool = mempool_create(DWARF_FRAME_MIN_REQ,
mempool_alloc_slab,
mempool_free_slab,
dwarf_frame_cachep);
entry = eh_frame_start;

dwarf_reg_pool = mempool_create(DWARF_REG_MIN_REQ,
mempool_alloc_slab,
mempool_free_slab,
dwarf_reg_cachep);

while ((char *)entry < __stop_eh_frame) {
while ((char *)entry < eh_frame_end) {
p = entry;

count = dwarf_entry_len(p, &len);
Expand All @@ -927,6 +921,7 @@ static int __init dwarf_unwinder_init(void)
* entry and move to the next one because 'len'
* tells us where our next entry is.
*/
err = -EINVAL;
goto out;
} else
p += count;
Expand All @@ -938,13 +933,14 @@ static int __init dwarf_unwinder_init(void)
p += 4;

if (entry_type == DW_EH_FRAME_CIE) {
err = dwarf_parse_cie(entry, p, len, end);
err = dwarf_parse_cie(entry, p, len, end, mod);
if (err < 0)
goto out;
else
c_entries++;
} else {
err = dwarf_parse_fde(entry, entry_type, p, len, end);
err = dwarf_parse_fde(entry, entry_type, p, len,
end, mod);
if (err < 0)
goto out;
else
Expand All @@ -957,6 +953,95 @@ static int __init dwarf_unwinder_init(void)
printk(KERN_INFO "DWARF unwinder initialised: read %u CIEs, %u FDEs\n",
c_entries, f_entries);

return 0;

out:
return err;
}

/**
* dwarf_module_unload - remove FDE/CIEs associated with @mod
* @mod: the module that is being unloaded
*
* Remove any FDEs and CIEs from the global lists that came from
* @mod's .eh_frame section because @mod is being unloaded.
*/
void dwarf_module_unload(struct module *mod)
{
struct dwarf_fde *fde;
struct dwarf_cie *cie;
unsigned long flags;

spin_lock_irqsave(&dwarf_cie_lock, flags);

again_cie:
list_for_each_entry(cie, &dwarf_cie_list, link) {
if (cie->mod == mod)
break;
}

if (&cie->link != &dwarf_cie_list) {
list_del(&cie->link);
kfree(cie);
goto again_cie;
}

spin_unlock_irqrestore(&dwarf_cie_lock, flags);

spin_lock_irqsave(&dwarf_fde_lock, flags);

again_fde:
list_for_each_entry(fde, &dwarf_fde_list, link) {
if (fde->mod == mod)
break;
}

if (&fde->link != &dwarf_fde_list) {
list_del(&fde->link);
kfree(fde);
goto again_fde;
}

spin_unlock_irqrestore(&dwarf_fde_lock, flags);
}

/**
* 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)
{
int err;
INIT_LIST_HEAD(&dwarf_cie_list);
INIT_LIST_HEAD(&dwarf_fde_list);

dwarf_frame_cachep = kmem_cache_create("dwarf_frames",
sizeof(struct dwarf_frame), 0,
SLAB_PANIC | SLAB_HWCACHE_ALIGN | SLAB_NOTRACK, NULL);

dwarf_reg_cachep = kmem_cache_create("dwarf_regs",
sizeof(struct dwarf_reg), 0,
SLAB_PANIC | SLAB_HWCACHE_ALIGN | SLAB_NOTRACK, 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);

err = dwarf_parse_section(__start_eh_frame, __stop_eh_frame, NULL);
if (err)
goto out;

err = unwinder_register(&dwarf_unwinder);
if (err)
goto out;
Expand Down
32 changes: 32 additions & 0 deletions arch/sh/kernel/module.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,7 @@
#include <linux/string.h>
#include <linux/kernel.h>
#include <asm/unaligned.h>
#include <asm/dwarf.h>

void *module_alloc(unsigned long size)
{
Expand Down Expand Up @@ -145,10 +146,41 @@ int module_finalize(const Elf_Ehdr *hdr,
const Elf_Shdr *sechdrs,
struct module *me)
{
#ifdef CONFIG_DWARF_UNWINDER
unsigned int i, err;
unsigned long start, end;
char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;

start = end = 0;

for (i = 1; i < hdr->e_shnum; i++) {
/* Alloc bit cleared means "ignore it." */
if ((sechdrs[i].sh_flags & SHF_ALLOC)
&& !strcmp(secstrings+sechdrs[i].sh_name, ".eh_frame")) {
start = sechdrs[i].sh_addr;
end = start + sechdrs[i].sh_size;
break;
}
}

/* Did we find the .eh_frame section? */
if (i != hdr->e_shnum) {
err = dwarf_parse_section((char *)start, (char *)end, me);
if (err)
printk(KERN_WARNING "%s: failed to parse DWARF info\n",
me->name);
}

#endif /* CONFIG_DWARF_UNWINDER */

return module_bug_finalize(hdr, sechdrs, me);
}

void module_arch_cleanup(struct module *mod)
{
module_bug_cleanup(mod);

#ifdef CONFIG_DWARF_UNWINDER
dwarf_module_unload(mod);
#endif /* CONFIG_DWARF_UNWINDER */
}

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