arch/tile: support backtracing on TILE-Gx
This functionality was stubbed out until recently. Now we support our
normal backtracing API on TILE-Gx as well as on TILE64/TILEPro.
This change includes a tweak to the instruction encoding caused by
adding addxli for compat mode.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
diff --git a/arch/tile/kernel/backtrace.c b/arch/tile/kernel/backtrace.c
index 77265f3..d3c41c1 100644
--- a/arch/tile/kernel/backtrace.c
+++ b/arch/tile/kernel/backtrace.c
@@ -19,9 +19,6 @@
#include <arch/chip.h>
-#if TILE_CHIP < 10
-
-
#include <asm/opcode-tile.h>
@@ -29,6 +26,27 @@
#define TREG_LR 55
+#if TILE_CHIP >= 10
+#define tile_bundle_bits tilegx_bundle_bits
+#define TILE_MAX_INSTRUCTIONS_PER_BUNDLE TILEGX_MAX_INSTRUCTIONS_PER_BUNDLE
+#define TILE_BUNDLE_ALIGNMENT_IN_BYTES TILEGX_BUNDLE_ALIGNMENT_IN_BYTES
+#define tile_decoded_instruction tilegx_decoded_instruction
+#define tile_mnemonic tilegx_mnemonic
+#define parse_insn_tile parse_insn_tilegx
+#define TILE_OPC_IRET TILEGX_OPC_IRET
+#define TILE_OPC_ADDI TILEGX_OPC_ADDI
+#define TILE_OPC_ADDLI TILEGX_OPC_ADDLI
+#define TILE_OPC_INFO TILEGX_OPC_INFO
+#define TILE_OPC_INFOL TILEGX_OPC_INFOL
+#define TILE_OPC_JRP TILEGX_OPC_JRP
+#define TILE_OPC_MOVE TILEGX_OPC_MOVE
+#define OPCODE_STORE TILEGX_OPC_ST
+typedef long long bt_int_reg_t;
+#else
+#define OPCODE_STORE TILE_OPC_SW
+typedef int bt_int_reg_t;
+#endif
+
/** A decoded bundle used for backtracer analysis. */
struct BacktraceBundle {
tile_bundle_bits bits;
@@ -41,7 +59,7 @@
/* This implementation only makes sense for native tools. */
/** Default function to read memory. */
static bool bt_read_memory(void *result, VirtualAddress addr,
- size_t size, void *extra)
+ unsigned int size, void *extra)
{
/* FIXME: this should do some horrible signal stuff to catch
* SEGV cleanly and fail.
@@ -106,6 +124,12 @@
find_matching_insn(bundle, TILE_OPC_ADDI, vals, 2);
if (insn == NULL)
insn = find_matching_insn(bundle, TILE_OPC_ADDLI, vals, 2);
+#if TILE_CHIP >= 10
+ if (insn == NULL)
+ insn = find_matching_insn(bundle, TILEGX_OPC_ADDXLI, vals, 2);
+ if (insn == NULL)
+ insn = find_matching_insn(bundle, TILEGX_OPC_ADDXI, vals, 2);
+#endif
if (insn == NULL)
return false;
@@ -190,13 +214,52 @@
return find_matching_insn(bundle, TILE_OPC_MOVE, vals, 2) != NULL;
}
-/** Does this bundle contain the instruction 'sw sp, lr'? */
+/** Does this bundle contain a store of lr to sp? */
static inline bool bt_has_sw_sp_lr(const struct BacktraceBundle *bundle)
{
static const int vals[2] = { TREG_SP, TREG_LR };
- return find_matching_insn(bundle, TILE_OPC_SW, vals, 2) != NULL;
+ return find_matching_insn(bundle, OPCODE_STORE, vals, 2) != NULL;
}
+#if TILE_CHIP >= 10
+/** Track moveli values placed into registers. */
+static inline void bt_update_moveli(const struct BacktraceBundle *bundle,
+ int moveli_args[])
+{
+ int i;
+ for (i = 0; i < bundle->num_insns; i++) {
+ const struct tile_decoded_instruction *insn =
+ &bundle->insns[i];
+
+ if (insn->opcode->mnemonic == TILEGX_OPC_MOVELI) {
+ int reg = insn->operand_values[0];
+ moveli_args[reg] = insn->operand_values[1];
+ }
+ }
+}
+
+/** Does this bundle contain an 'add sp, sp, reg' instruction
+ * from a register that we saw a moveli into, and if so, what
+ * is the value in the register?
+ */
+static bool bt_has_add_sp(const struct BacktraceBundle *bundle, int *adjust,
+ int moveli_args[])
+{
+ static const int vals[2] = { TREG_SP, TREG_SP };
+
+ const struct tile_decoded_instruction *insn =
+ find_matching_insn(bundle, TILEGX_OPC_ADDX, vals, 2);
+ if (insn) {
+ int reg = insn->operand_values[2];
+ if (moveli_args[reg]) {
+ *adjust = moveli_args[reg];
+ return true;
+ }
+ }
+ return false;
+}
+#endif
+
/** Locates the caller's PC and SP for a program starting at the
* given address.
*/
@@ -227,6 +290,11 @@
int next_bundle = 0;
VirtualAddress pc;
+#if TILE_CHIP >= 10
+ /* Naively try to track moveli values to support addx for -m32. */
+ int moveli_args[TILEGX_NUM_REGISTERS] = { 0 };
+#endif
+
/* Default to assuming that the caller's sp is the current sp.
* This is necessary to handle the case where we start backtracing
* right at the end of the epilog.
@@ -380,7 +448,11 @@
if (!sp_determined) {
int adjust;
- if (bt_has_addi_sp(&bundle, &adjust)) {
+ if (bt_has_addi_sp(&bundle, &adjust)
+#if TILE_CHIP >= 10
+ || bt_has_add_sp(&bundle, &adjust, moveli_args)
+#endif
+ ) {
location->sp_location = SP_LOC_OFFSET;
if (adjust <= 0) {
@@ -427,6 +499,11 @@
sp_determined = true;
}
}
+
+#if TILE_CHIP >= 10
+ /* Track moveli arguments for -m32 mode. */
+ bt_update_moveli(&bundle, moveli_args);
+#endif
}
if (bt_has_iret(&bundle)) {
@@ -502,11 +579,10 @@
break;
}
- /* The frame pointer should theoretically be aligned mod 8. If
- * it's not even aligned mod 4 then something terrible happened
- * and we should mark it as invalid.
+ /* If the frame pointer is not aligned to the basic word size
+ * something terrible happened and we should mark it as invalid.
*/
- if (fp % 4 != 0)
+ if (fp % sizeof(bt_int_reg_t) != 0)
fp = -1;
/* -1 means "don't know initial_frame_caller_pc". */
@@ -547,9 +623,16 @@
state->read_memory_func_extra = read_memory_func_extra;
}
+/* Handle the case where the register holds more bits than the VA. */
+static bool valid_addr_reg(bt_int_reg_t reg)
+{
+ return ((VirtualAddress)reg == reg);
+}
+
bool backtrace_next(BacktraceIterator *state)
{
- VirtualAddress next_fp, next_pc, next_frame[2];
+ VirtualAddress next_fp, next_pc;
+ bt_int_reg_t next_frame[2];
if (state->fp == -1) {
/* No parent frame. */
@@ -563,11 +646,9 @@
}
next_fp = next_frame[1];
- if (next_fp % 4 != 0) {
- /* Caller's frame pointer is suspect, so give up.
- * Technically it should be aligned mod 8, but we will
- * be forgiving here.
- */
+ if (!valid_addr_reg(next_frame[1]) ||
+ next_fp % sizeof(bt_int_reg_t) != 0) {
+ /* Caller's frame pointer is suspect, so give up. */
return false;
}
@@ -585,7 +666,7 @@
} else {
/* Get the caller PC from the frame linkage area. */
next_pc = next_frame[0];
- if (next_pc == 0 ||
+ if (!valid_addr_reg(next_frame[0]) || next_pc == 0 ||
next_pc % TILE_BUNDLE_ALIGNMENT_IN_BYTES != 0) {
/* The PC is suspect, so give up. */
return false;
@@ -599,23 +680,3 @@
return true;
}
-
-#else /* TILE_CHIP < 10 */
-
-void backtrace_init(BacktraceIterator *state,
- BacktraceMemoryReader read_memory_func,
- void *read_memory_func_extra,
- VirtualAddress pc, VirtualAddress lr,
- VirtualAddress sp, VirtualAddress r52)
-{
- state->pc = pc;
- state->sp = sp;
- state->fp = -1;
- state->initial_frame_caller_pc = -1;
- state->read_memory_func = read_memory_func;
- state->read_memory_func_extra = read_memory_func_extra;
-}
-
-bool backtrace_next(BacktraceIterator *state) { return false; }
-
-#endif /* TILE_CHIP < 10 */