Currently the only user for debug heap is kdbnearsym() which can be
modified to rather ask the caller to supply a buffer for symbol name.
So do that and modify kdbnearsym() callers to pass a symbol name buffer
allocated statically and hence remove custom debug heap allocator.
This change has been tested using kgdbtest on arm64 which doesn't show
any regressions.
Suggested-by: Daniel Thompson <daniel.thomp...@linaro.org>
Signed-off-by: Sumit Garg <sumit.g...@linaro.org>
---
Changes in v2:
- Allocate namebuf statically instead of stack to maintain debugger
robustness.
kernel/debug/kdb/kdb_debugger.c | 1 -
kernel/debug/kdb/kdb_main.c | 6 +-
kernel/debug/kdb/kdb_private.h | 7 +-
kernel/debug/kdb/kdb_support.c | 294 +-------------------------------
4 files changed, 11 insertions(+), 297 deletions(-)
diff --git a/kernel/debug/kdb/kdb_debugger.c b/kernel/debug/kdb/kdb_debugger.c
index 0220afda3200..e91fc3e4edd5 100644
--- a/kernel/debug/kdb/kdb_debugger.c
+++ b/kernel/debug/kdb/kdb_debugger.c
@@ -140,7 +140,6 @@ int kdb_stub(struct kgdb_state *ks)
*/
kdb_common_deinit_state();
KDB_STATE_CLEAR(PAGER);
- kdbnearsym_cleanup();
if (error == KDB_CMD_KGDB) {
if (KDB_STATE(DOING_KGDB))
KDB_STATE_CLEAR(DOING_KGDB);
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index 9d69169582c6..6efe9ec53906 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -526,6 +526,7 @@ int kdbgetaddrarg(int argc, const char **argv, int *nextarg,
char symbol = '\0';
char *cp;
kdb_symtab_t symtab;
+ static char namebuf[KSYM_NAME_LEN];
/*
* If the enable flags prohibit both arbitrary memory access
@@ -585,7 +586,7 @@ int kdbgetaddrarg(int argc, const char **argv, int *nextarg,
}
if (!found)
- found = kdbnearsym(addr, &symtab);
+ found = kdbnearsym(addr, &symtab, namebuf);
(*nextarg)++;
@@ -1503,6 +1504,7 @@ static void kdb_md_line(const char *fmtstr, unsigned long
addr,
int i;
int j;
unsigned long word;
+ static char namebuf[KSYM_NAME_LEN];
memset(cbuf, '\0', sizeof(cbuf));
if (phys)
@@ -1518,7 +1520,7 @@ static void kdb_md_line(const char *fmtstr, unsigned long
addr,
break;
kdb_printf(fmtstr, word);
if (symbolic)
- kdbnearsym(word, &symtab);
+ kdbnearsym(word, &symtab, namebuf);
else
memset(&symtab, 0, sizeof(symtab));
if (symtab.sym_name) {
diff --git a/kernel/debug/kdb/kdb_private.h b/kernel/debug/kdb/kdb_private.h
index b857a84de3b5..1707eeebc59a 100644
--- a/kernel/debug/kdb/kdb_private.h
+++ b/kernel/debug/kdb/kdb_private.h
@@ -108,8 +108,7 @@ extern char *kdbgetenv(const char *);
extern int kdbgetaddrarg(int, const char **, int*, unsigned long *,
long *, char **);
extern int kdbgetsymval(const char *, kdb_symtab_t *);
-extern int kdbnearsym(unsigned long, kdb_symtab_t *);
-extern void kdbnearsym_cleanup(void);
+extern int kdbnearsym(unsigned long addr, kdb_symtab_t *symtab, char *namebuf);
extern char *kdb_strdup(const char *str, gfp_t type);
extern void kdb_symbol_print(unsigned long, const kdb_symtab_t *, unsigned
int);
@@ -233,10 +232,6 @@ extern struct task_struct *kdb_curr_task(int);
#define GFP_KDB (in_dbg_master() ? GFP_ATOMIC : GFP_KERNEL)
-extern void *debug_kmalloc(size_t size, gfp_t flags);
-extern void debug_kfree(void *);
-extern void debug_kusage(void);
-
extern struct task_struct *kdb_current_task;
extern struct pt_regs *kdb_current_regs;
diff --git a/kernel/debug/kdb/kdb_support.c b/kernel/debug/kdb/kdb_support.c
index b59aad1f0b55..9b907a84f2db 100644
--- a/kernel/debug/kdb/kdb_support.c
+++ b/kernel/debug/kdb/kdb_support.c
@@ -57,8 +57,6 @@ int kdbgetsymval(const char *symname, kdb_symtab_t *symtab)
}
EXPORT_SYMBOL(kdbgetsymval);
-static char *kdb_name_table[100]; /* arbitrary size */
-
/*
* kdbnearsym - Return the name of the symbol with the nearest address
* less than 'addr'.
@@ -79,13 +77,11 @@ static char *kdb_name_table[100]; /* arbitrary size */
* hold active strings, no kdb caller of kdbnearsym makes more
* than ~20 later calls before using a saved value.
*/
-int kdbnearsym(unsigned long addr, kdb_symtab_t *symtab)
+int kdbnearsym(unsigned long addr, kdb_symtab_t *symtab, char *namebuf)
{
int ret = 0;
unsigned long symbolsize = 0;
unsigned long offset = 0;
-#define knt1_size 128 /* must be >= kallsyms table size */
- char *knt1 = NULL;
if (KDB_DEBUG(AR))
kdb_printf("kdbnearsym: addr=0x%lx, symtab=%px\n", addr,
symtab);
@@ -93,14 +89,9 @@ int kdbnearsym(unsigned long addr, kdb_symtab_t *symtab)
if (addr < 4096)
goto out;
- knt1 = debug_kmalloc(knt1_size, GFP_ATOMIC);
- if (!knt1) {
- kdb_printf("kdbnearsym: addr=0x%lx cannot kmalloc knt1\n",
- addr);
- goto out;
- }
+
symtab->sym_name = kallsyms_lookup(addr, &symbolsize , &offset,
- (char **)(&symtab->mod_name), knt1);
+ (char **)(&symtab->mod_name), namebuf);
if (offset > 8*1024*1024) {
symtab->sym_name = NULL;
addr = offset = symbolsize = 0;
@@ -109,42 +100,6 @@ int kdbnearsym(unsigned long addr, kdb_symtab_t *symtab)
symtab->sym_end = symtab->sym_start + symbolsize;
ret = symtab->sym_name != NULL && *(symtab->sym_name) != '\0';
- if (ret) {
- int i;
- /* Another 2.6 kallsyms "feature". Sometimes the sym_name is
- * set but the buffer passed into kallsyms_lookup is not used,
- * so it contains garbage. The caller has to work out which
- * buffer needs to be saved.
- *
- * What was Rusty smoking when he wrote that code?
- */
- if (symtab->sym_name != knt1) {
- strncpy(knt1, symtab->sym_name, knt1_size);
- knt1[knt1_size-1] = '\0';
- }
- for (i = 0; i < ARRAY_SIZE(kdb_name_table); ++i) {
- if (kdb_name_table[i] &&
- strcmp(kdb_name_table[i], knt1) == 0)
- break;
- }
- if (i >= ARRAY_SIZE(kdb_name_table)) {
- debug_kfree(kdb_name_table[0]);
- memmove(kdb_name_table, kdb_name_table+1,
- sizeof(kdb_name_table[0]) *
- (ARRAY_SIZE(kdb_name_table)-1));
- } else {
- debug_kfree(knt1);
- knt1 = kdb_name_table[i];
- memmove(kdb_name_table+i, kdb_name_table+i+1,
- sizeof(kdb_name_table[0]) *
- (ARRAY_SIZE(kdb_name_table)-i-1));
- }
- i = ARRAY_SIZE(kdb_name_table) - 1;
- kdb_name_table[i] = knt1;
- symtab->sym_name = kdb_name_table[i];
- knt1 = NULL;
- }
-
if (symtab->mod_name == NULL)
symtab->mod_name = "kernel";
if (KDB_DEBUG(AR))
@@ -152,23 +107,10 @@ int kdbnearsym(unsigned long addr, kdb_symtab_t *symtab)
"symtab->mod_name=%px, symtab->sym_name=%px (%s)\n", ret,
symtab->sym_start, symtab->mod_name, symtab->sym_name,
symtab->sym_name);
-
out:
- debug_kfree(knt1);
return ret;
}
-void kdbnearsym_cleanup(void)
-{
- int i;
- for (i = 0; i < ARRAY_SIZE(kdb_name_table); ++i) {
- if (kdb_name_table[i]) {
- debug_kfree(kdb_name_table[i]);
- kdb_name_table[i] = NULL;
- }
- }
-}
-
static char ks_namebuf[KSYM_NAME_LEN+1], ks_namebuf_prev[KSYM_NAME_LEN+1];
/*
@@ -259,11 +201,13 @@ void kdb_symbol_print(unsigned long addr, const
kdb_symtab_t *symtab_p,
unsigned int punc)
{
kdb_symtab_t symtab, *symtab_p2;
+ static char namebuf[KSYM_NAME_LEN];
+
if (symtab_p) {
symtab_p2 = (kdb_symtab_t *)symtab_p;
} else {
symtab_p2 = &symtab;
- kdbnearsym(addr, symtab_p2);
+ kdbnearsym(addr, symtab_p2, namebuf);
}
if (!(symtab_p2->sym_name || (punc & KDB_SP_VALUE)))
return;
@@ -665,232 +609,6 @@ unsigned long kdb_task_state(const struct task_struct *p,
unsigned long mask)
return (mask & kdb_task_state_string(state)) != 0;
}
-/* Last ditch allocator for debugging, so we can still debug even when
- * the GFP_ATOMIC pool has been exhausted. The algorithms are tuned
- * for space usage, not for speed. One smallish memory pool, the free
- * chain is always in ascending address order to allow coalescing,
- * allocations are done in brute force best fit.
- */
-
-struct debug_alloc_header {
- u32 next; /* offset of next header from start of pool */
- u32 size;
- void *caller;
-};
-
-/* The memory returned by this allocator must be aligned, which means
- * so must the header size. Do not assume that sizeof(struct
- * debug_alloc_header) is a multiple of the alignment, explicitly
- * calculate the overhead of this header, including the alignment.
- * The rest of this code must not use sizeof() on any header or
- * pointer to a header.
- */
-#define dah_align 8
-#define dah_overhead ALIGN(sizeof(struct debug_alloc_header), dah_align)
-
-static u64 debug_alloc_pool_aligned[256*1024/dah_align]; /* 256K pool */
-static char *debug_alloc_pool = (char *)debug_alloc_pool_aligned;
-static u32 dah_first, dah_first_call = 1, dah_used, dah_used_max;
-
-/* Locking is awkward. The debug code is called from all contexts,
- * including non maskable interrupts. A normal spinlock is not safe
- * in NMI context. Try to get the debug allocator lock, if it cannot
- * be obtained after a second then give up. If the lock could not be
- * previously obtained on this cpu then only try once.
- *
- * sparse has no annotation for "this function _sometimes_ acquires a
- * lock", so fudge the acquire/release notation.
- */
-static DEFINE_SPINLOCK(dap_lock);
-static int get_dap_lock(void)
- __acquires(dap_lock)
-{
- static int dap_locked = -1;
- int count;
- if (dap_locked == smp_processor_id())
- count = 1;
- else
- count = 1000;
- while (1) {
- if (spin_trylock(&dap_lock)) {
- dap_locked = -1;
- return 1;
- }
- if (!count--)
- break;
- udelay(1000);
- }
- dap_locked = smp_processor_id();
- __acquire(dap_lock);
- return 0;
-}
-
-void *debug_kmalloc(size_t size, gfp_t flags)
-{
- unsigned int rem, h_offset;
- struct debug_alloc_header *best, *bestprev, *prev, *h;
- void *p = NULL;
- if (!get_dap_lock()) {
- __release(dap_lock); /* we never actually got it */
- return NULL;
- }
- h = (struct debug_alloc_header *)(debug_alloc_pool + dah_first);
- if (dah_first_call) {
- h->size = sizeof(debug_alloc_pool_aligned) - dah_overhead;
- dah_first_call = 0;
- }
- size = ALIGN(size, dah_align);
- prev = best = bestprev = NULL;
- while (1) {
- if (h->size >= size && (!best || h->size < best->size)) {
- best = h;
- bestprev = prev;
- if (h->size == size)
- break;
- }
- if (!h->next)
- break;
- prev = h;
- h = (struct debug_alloc_header *)(debug_alloc_pool + h->next);
- }
- if (!best)
- goto out;
- rem = best->size - size;
- /* The pool must always contain at least one header */
- if (best->next == 0 && bestprev == NULL && rem < dah_overhead)
- goto out;
- if (rem >= dah_overhead) {
- best->size = size;
- h_offset = ((char *)best - debug_alloc_pool) +
- dah_overhead + best->size;
- h = (struct debug_alloc_header *)(debug_alloc_pool + h_offset);
- h->size = rem - dah_overhead;
- h->next = best->next;
- } else
- h_offset = best->next;
- best->caller = __builtin_return_address(0);
- dah_used += best->size;
- dah_used_max = max(dah_used, dah_used_max);
- if (bestprev)
- bestprev->next = h_offset;
- else
- dah_first = h_offset;
- p = (char *)best + dah_overhead;
- memset(p, POISON_INUSE, best->size - 1);
- *((char *)p + best->size - 1) = POISON_END;
-out:
- spin_unlock(&dap_lock);
- return p;
-}
-
-void debug_kfree(void *p)
-{
- struct debug_alloc_header *h;
- unsigned int h_offset;
- if (!p)
- return;
- if ((char *)p < debug_alloc_pool ||
- (char *)p >= debug_alloc_pool + sizeof(debug_alloc_pool_aligned)) {
- kfree(p);
- return;
- }
- if (!get_dap_lock()) {
- __release(dap_lock); /* we never actually got it */
- return; /* memory leak, cannot be helped */
- }
- h = (struct debug_alloc_header *)((char *)p - dah_overhead);
- memset(p, POISON_FREE, h->size - 1);
- *((char *)p + h->size - 1) = POISON_END;
- h->caller = NULL;
- dah_used -= h->size;
- h_offset = (char *)h - debug_alloc_pool;
- if (h_offset < dah_first) {
- h->next = dah_first;
- dah_first = h_offset;
- } else {
- struct debug_alloc_header *prev;
- unsigned int prev_offset;
- prev = (struct debug_alloc_header *)(debug_alloc_pool +
- dah_first);
- while (1) {
- if (!prev->next || prev->next > h_offset)
- break;
- prev = (struct debug_alloc_header *)
- (debug_alloc_pool + prev->next);
- }
- prev_offset = (char *)prev - debug_alloc_pool;
- if (prev_offset + dah_overhead + prev->size == h_offset) {
- prev->size += dah_overhead + h->size;
- memset(h, POISON_FREE, dah_overhead - 1);
- *((char *)h + dah_overhead - 1) = POISON_END;
- h = prev;
- h_offset = prev_offset;
- } else {
- h->next = prev->next;
- prev->next = h_offset;
- }
- }
- if (h_offset + dah_overhead + h->size == h->next) {
- struct debug_alloc_header *next;
- next = (struct debug_alloc_header *)
- (debug_alloc_pool + h->next);
- h->size += dah_overhead + next->size;
- h->next = next->next;
- memset(next, POISON_FREE, dah_overhead - 1);
- *((char *)next + dah_overhead - 1) = POISON_END;
- }
- spin_unlock(&dap_lock);
-}
-
-void debug_kusage(void)
-{
- struct debug_alloc_header *h_free, *h_used;
-#ifdef CONFIG_IA64
- /* FIXME: using dah for ia64 unwind always results in a memory leak.
- * Fix that memory leak first, then set debug_kusage_one_time = 1 for
- * all architectures.
- */
- static int debug_kusage_one_time;
-#else
- static int debug_kusage_one_time = 1;
-#endif
- if (!get_dap_lock()) {
- __release(dap_lock); /* we never actually got it */
- return;
- }
- h_free = (struct debug_alloc_header *)(debug_alloc_pool + dah_first);
- if (dah_first == 0 &&
- (h_free->size == sizeof(debug_alloc_pool_aligned) - dah_overhead ||
- dah_first_call))
- goto out;
- if (!debug_kusage_one_time)
- goto out;
- debug_kusage_one_time = 0;
- kdb_printf("%s: debug_kmalloc memory leak dah_first %d\n",
- __func__, dah_first);
- if (dah_first) {
- h_used = (struct debug_alloc_header *)debug_alloc_pool;
- kdb_printf("%s: h_used %px size %d\n", __func__, h_used,
- h_used->size);
- }
- do {
- h_used = (struct debug_alloc_header *)
- ((char *)h_free + dah_overhead + h_free->size);
- kdb_printf("%s: h_used %px size %d caller %px\n",
- __func__, h_used, h_used->size, h_used->caller);
- h_free = (struct debug_alloc_header *)
- (debug_alloc_pool + h_free->next);
- } while (h_free->next);
- h_used = (struct debug_alloc_header *)
- ((char *)h_free + dah_overhead + h_free->size);
- if ((char *)h_used - debug_alloc_pool !=
- sizeof(debug_alloc_pool_aligned))
- kdb_printf("%s: h_used %px size %d caller %px\n",
- __func__, h_used, h_used->size, h_used->caller);
-out:
- spin_unlock(&dap_lock);
-}
-
/* Maintain a small stack of kdb_flags to allow recursion without disturbing
* the global kdb state.
*/
--
2.25.1
