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Diffstat (limited to 'arch/arm/kernel/unwind.c')
-rw-r--r--arch/arm/kernel/unwind.c137
1 files changed, 100 insertions, 37 deletions
diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c
index 00df012c4678..3c217694ebec 100644
--- a/arch/arm/kernel/unwind.c
+++ b/arch/arm/kernel/unwind.c
@@ -68,6 +68,12 @@ EXPORT_SYMBOL(__aeabi_unwind_cpp_pr2);
struct unwind_ctrl_block {
unsigned long vrs[16]; /* virtual register set */
const unsigned long *insn; /* pointer to the current instructions word */
+ unsigned long sp_high; /* highest value of sp allowed */
+ /*
+ * 1 : check for stack overflow for each register pop.
+ * 0 : save overhead if there is plenty of stack remaining.
+ */
+ int check_each_pop;
int entries; /* number of entries left to interpret */
int byte; /* current byte number in the instructions word */
};
@@ -235,12 +241,85 @@ static unsigned long unwind_get_byte(struct unwind_ctrl_block *ctrl)
return ret;
}
+/* Before poping a register check whether it is feasible or not */
+static int unwind_pop_register(struct unwind_ctrl_block *ctrl,
+ unsigned long **vsp, unsigned int reg)
+{
+ if (unlikely(ctrl->check_each_pop))
+ if (*vsp >= (unsigned long *)ctrl->sp_high)
+ return -URC_FAILURE;
+
+ ctrl->vrs[reg] = *(*vsp)++;
+ return URC_OK;
+}
+
+/* Helper functions to execute the instructions */
+static int unwind_exec_pop_subset_r4_to_r13(struct unwind_ctrl_block *ctrl,
+ unsigned long mask)
+{
+ unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
+ int load_sp, reg = 4;
+
+ load_sp = mask & (1 << (13 - 4));
+ while (mask) {
+ if (mask & 1)
+ if (unwind_pop_register(ctrl, &vsp, reg))
+ return -URC_FAILURE;
+ mask >>= 1;
+ reg++;
+ }
+ if (!load_sp)
+ ctrl->vrs[SP] = (unsigned long)vsp;
+
+ return URC_OK;
+}
+
+static int unwind_exec_pop_r4_to_rN(struct unwind_ctrl_block *ctrl,
+ unsigned long insn)
+{
+ unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
+ int reg;
+
+ /* pop R4-R[4+bbb] */
+ for (reg = 4; reg <= 4 + (insn & 7); reg++)
+ if (unwind_pop_register(ctrl, &vsp, reg))
+ return -URC_FAILURE;
+
+ if (insn & 0x80)
+ if (unwind_pop_register(ctrl, &vsp, 14))
+ return -URC_FAILURE;
+
+ ctrl->vrs[SP] = (unsigned long)vsp;
+
+ return URC_OK;
+}
+
+static int unwind_exec_pop_subset_r0_to_r3(struct unwind_ctrl_block *ctrl,
+ unsigned long mask)
+{
+ unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
+ int reg = 0;
+
+ /* pop R0-R3 according to mask */
+ while (mask) {
+ if (mask & 1)
+ if (unwind_pop_register(ctrl, &vsp, reg))
+ return -URC_FAILURE;
+ mask >>= 1;
+ reg++;
+ }
+ ctrl->vrs[SP] = (unsigned long)vsp;
+
+ return URC_OK;
+}
+
/*
* Execute the current unwind instruction.
*/
static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
{
unsigned long insn = unwind_get_byte(ctrl);
+ int ret = URC_OK;
pr_debug("%s: insn = %08lx\n", __func__, insn);
@@ -250,8 +329,6 @@ static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
ctrl->vrs[SP] -= ((insn & 0x3f) << 2) + 4;
else if ((insn & 0xf0) == 0x80) {
unsigned long mask;
- unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
- int load_sp, reg = 4;
insn = (insn << 8) | unwind_get_byte(ctrl);
mask = insn & 0x0fff;
@@ -261,29 +338,16 @@ static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
return -URC_FAILURE;
}
- /* pop R4-R15 according to mask */
- load_sp = mask & (1 << (13 - 4));
- while (mask) {
- if (mask & 1)
- ctrl->vrs[reg] = *vsp++;
- mask >>= 1;
- reg++;
- }
- if (!load_sp)
- ctrl->vrs[SP] = (unsigned long)vsp;
+ ret = unwind_exec_pop_subset_r4_to_r13(ctrl, mask);
+ if (ret)
+ goto error;
} else if ((insn & 0xf0) == 0x90 &&
(insn & 0x0d) != 0x0d)
ctrl->vrs[SP] = ctrl->vrs[insn & 0x0f];
else if ((insn & 0xf0) == 0xa0) {
- unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
- int reg;
-
- /* pop R4-R[4+bbb] */
- for (reg = 4; reg <= 4 + (insn & 7); reg++)
- ctrl->vrs[reg] = *vsp++;
- if (insn & 0x80)
- ctrl->vrs[14] = *vsp++;
- ctrl->vrs[SP] = (unsigned long)vsp;
+ ret = unwind_exec_pop_r4_to_rN(ctrl, insn);
+ if (ret)
+ goto error;
} else if (insn == 0xb0) {
if (ctrl->vrs[PC] == 0)
ctrl->vrs[PC] = ctrl->vrs[LR];
@@ -291,8 +355,6 @@ static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
ctrl->entries = 0;
} else if (insn == 0xb1) {
unsigned long mask = unwind_get_byte(ctrl);
- unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
- int reg = 0;
if (mask == 0 || mask & 0xf0) {
pr_warning("unwind: Spare encoding %04lx\n",
@@ -300,14 +362,9 @@ static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
return -URC_FAILURE;
}
- /* pop R0-R3 according to mask */
- while (mask) {
- if (mask & 1)
- ctrl->vrs[reg] = *vsp++;
- mask >>= 1;
- reg++;
- }
- ctrl->vrs[SP] = (unsigned long)vsp;
+ ret = unwind_exec_pop_subset_r0_to_r3(ctrl, mask);
+ if (ret)
+ goto error;
} else if (insn == 0xb2) {
unsigned long uleb128 = unwind_get_byte(ctrl);
@@ -320,7 +377,8 @@ static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
pr_debug("%s: fp = %08lx sp = %08lx lr = %08lx pc = %08lx\n", __func__,
ctrl->vrs[FP], ctrl->vrs[SP], ctrl->vrs[LR], ctrl->vrs[PC]);
- return URC_OK;
+error:
+ return ret;
}
/*
@@ -329,13 +387,13 @@ static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
*/
int unwind_frame(struct stackframe *frame)
{
- unsigned long high, low;
+ unsigned long low;
const struct unwind_idx *idx;
struct unwind_ctrl_block ctrl;
- /* only go to a higher address on the stack */
+ /* store the highest address on the stack to avoid crossing it*/
low = frame->sp;
- high = ALIGN(low, THREAD_SIZE);
+ ctrl.sp_high = ALIGN(low, THREAD_SIZE);
pr_debug("%s(pc = %08lx lr = %08lx sp = %08lx)\n", __func__,
frame->pc, frame->lr, frame->sp);
@@ -382,11 +440,16 @@ int unwind_frame(struct stackframe *frame)
return -URC_FAILURE;
}
+ ctrl.check_each_pop = 0;
+
while (ctrl.entries > 0) {
- int urc = unwind_exec_insn(&ctrl);
+ int urc;
+ if ((ctrl.sp_high - ctrl.vrs[SP]) < sizeof(ctrl.vrs))
+ ctrl.check_each_pop = 1;
+ urc = unwind_exec_insn(&ctrl);
if (urc < 0)
return urc;
- if (ctrl.vrs[SP] < low || ctrl.vrs[SP] >= high)
+ if (ctrl.vrs[SP] < low || ctrl.vrs[SP] >= ctrl.sp_high)
return -URC_FAILURE;
}
generated by cgit v1.2.3 (git 2.39.0) at 2024-12-01 21:05:45 +0300