Newer gcc versions generate a warning about accessing an array out of
bounds:
In function 'search_index',
inlined from 'unwind_find_idx' at arch/arm/lib32/unwind.c:109: ,
inlined from 'unwind_frame' at arch/arm/lib32/unwind.c:248:8:
arch/arm/lib32/unwind.c:86:32: warning: array subscript -1 is outside array bounds of 'struct unwind_idx[268435455]' [-Warray-bounds]
86 | } else if (addr >= last->addr)
| ~~~~^~~~~~
arch/arm/lib32/unwind.c: In function 'unwind_frame':
arch/arm/lib32/unwind.c:46:26: note: at offset -8 into object '__stop_unwind_idx' of size [0, 2147483647]
46 | extern struct unwind_idx __stop_unwind_idx[];
| ^~~~~~~~~~~~~~~~~
This was fixed by accident in the Kernel back in 2011 in
de66a979012d ("ARM: 7187/1: fix unwinding for XIP kernels") . Adopt that
commit for barebox.
Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
---
arch/arm/include/asm/unwind.h | 7 +-
arch/arm/lib32/unwind.c | 116 +++++++++++++++++++++++-----------
2 files changed, 84 insertions(+), 39 deletions(-)
diff --git a/arch/arm/include/asm/unwind.h b/arch/arm/include/asm/unwind.h
index 319527ec9b..37aba2aa4c 100644
--- a/arch/arm/include/asm/unwind.h
+++ b/arch/arm/include/asm/unwind.h
@@ -16,14 +16,15 @@ enum unwind_reason_code {
};
struct unwind_idx {
- unsigned long addr;
+ unsigned long addr_offset;
unsigned long insn;
};
struct unwind_table {
struct list_head list;
- struct unwind_idx *start;
- struct unwind_idx *stop;
+ const struct unwind_idx *start;
+ const struct unwind_idx *origin;
+ const struct unwind_idx *stop;
unsigned long begin_addr;
unsigned long end_addr;
};
diff --git a/arch/arm/lib32/unwind.c b/arch/arm/lib32/unwind.c
index 79bf7420d7..6f73cb1b73 100644
--- a/arch/arm/lib32/unwind.c
+++ b/arch/arm/lib32/unwind.c
@@ -28,7 +28,7 @@ EXPORT_SYMBOL(__aeabi_unwind_cpp_pr2);
struct unwind_ctrl_block {
unsigned long vrs[16]; /* virtual register set */
- unsigned long *insn; /* pointer to the current instructions word */
+ const unsigned long *insn; /* pointer to the current instructions word */
int entries; /* number of entries left to interpret */
int byte; /* current byte number in the instructions word */
};
@@ -42,8 +42,9 @@ enum regs {
#define THREAD_SIZE 8192
-extern struct unwind_idx __start_unwind_idx[];
-extern struct unwind_idx __stop_unwind_idx[];
+extern const struct unwind_idx __start_unwind_idx[];
+static const struct unwind_idx *__origin_unwind_idx;
+extern const struct unwind_idx __stop_unwind_idx[];
/* Convert a prel31 symbol to an absolute address */
#define prel31_to_addr(ptr) \
@@ -71,44 +72,99 @@ static void dump_backtrace_entry(unsigned long where, unsigned long from,
}
/*
- * Binary search in the unwind index. The entries entries are
+ * Binary search in the unwind index. The entries are
* guaranteed to be sorted in ascending order by the linker.
+ *
+ * start = first entry
+ * origin = first entry with positive offset (or stop if there is no such entry)
+ * stop - 1 = last entry
*/
-static struct unwind_idx *search_index(unsigned long addr,
- struct unwind_idx *first,
- struct unwind_idx *last)
+static const struct unwind_idx *search_index(unsigned long addr,
+ const struct unwind_idx *start,
+ const struct unwind_idx *origin,
+ const struct unwind_idx *stop)
{
- pr_debug("%s(%08lx, %p, %p)\n", __func__, addr, first, last);
+ unsigned long addr_prel31;
+
+ pr_debug("%s(%08lx, %p, %p, %p)\n",
+ __func__, addr, start, origin, stop);
+
+ /*
+ * only search in the section with the matching sign. This way the
+ * prel31 numbers can be compared as unsigned longs.
+ */
+ if (addr < (unsigned long)start)
+ /* negative offsets: [start; origin) */
+ stop = origin;
+ else
+ /* positive offsets: [origin; stop) */
+ start = origin;
+
+ /* prel31 for address relavive to start */
+ addr_prel31 = (addr - (unsigned long)start) & 0x7fffffff;
+
+ while (start < stop - 1) {
+ const struct unwind_idx *mid = start + ((stop - start) >> 1);
+
+ /*
+ * As addr_prel31 is relative to start an offset is needed to
+ * make it relative to mid.
+ */
+ if (addr_prel31 - ((unsigned long)mid - (unsigned long)start) <
+ mid->addr_offset)
+ stop = mid;
+ else {
+ /* keep addr_prel31 relative to start */
+ addr_prel31 -= ((unsigned long)mid -
+ (unsigned long)start);
+ start = mid;
+ }
+ }
- if (addr < first->addr) {
+ if (likely(start->addr_offset <= addr_prel31))
+ return start;
+ else {
pr_warning("unwind: Unknown symbol address %08lx\n", addr);
return NULL;
- } else if (addr >= last->addr)
- return last;
+ }
+}
- while (first < last - 1) {
- struct unwind_idx *mid = first + ((last - first + 1) >> 1);
+static const struct unwind_idx *unwind_find_origin(
+ const struct unwind_idx *start, const struct unwind_idx *stop)
+{
+ pr_debug("%s(%p, %p)\n", __func__, start, stop);
+ while (start < stop - 1) {
+ const struct unwind_idx *mid = start + ((stop - start) >> 1);
- if (addr < mid->addr)
- last = mid;
+ if (mid->addr_offset >= 0x40000000)
+ /* negative offset */
+ start = mid;
else
- first = mid;
+ /* positive offset */
+ stop = mid;
}
- return first;
-}
+ pr_debug("%s -> %p\n", __func__, stop);
+ return stop;
+ }
-static struct unwind_idx *unwind_find_idx(unsigned long addr)
+static const struct unwind_idx *unwind_find_idx(unsigned long addr)
{
- struct unwind_idx *idx = NULL;
+ const struct unwind_idx *idx = NULL;
pr_debug("%s(%08lx)\n", __func__, addr);
- if (is_kernel_text(addr))
+ if (is_kernel_text(addr)) {
+ if (unlikely(!__origin_unwind_idx))
+ __origin_unwind_idx =
+ unwind_find_origin(__start_unwind_idx,
+ __stop_unwind_idx);
+
/* main unwind table */
idx = search_index(addr, __start_unwind_idx,
- __stop_unwind_idx - 1);
- else {
+ __origin_unwind_idx,
+ __stop_unwind_idx);
+ } else {
/* module unwinding not supported */
}
@@ -232,7 +288,7 @@ static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
int unwind_frame(struct stackframe *frame)
{
unsigned long high, low;
- struct unwind_idx *idx;
+ const struct unwind_idx *idx;
struct unwind_ctrl_block ctrl;
/* only go to a higher address on the stack */
@@ -342,15 +398,3 @@ void dump_stack(void)
{
unwind_backtrace(NULL);
}
-
-static int unwind_init(void)
-{
- struct unwind_idx *idx;
-
- /* Convert the symbol addresses to absolute values */
- for (idx = __start_unwind_idx; idx < __stop_unwind_idx; idx++)
- idx->addr = prel31_to_addr(&idx->addr);
-
- return 0;
-}
-core_initcall(unwind_init);
--
2.30.2
