From: Zecheng Li <zecheng@google.com>
To: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>, Ian Rogers <irogers@google.com>,
Adrian Hunter <adrian.hunter@intel.com>,
Masami Hiramatsu <mhiramat@kernel.org>
Cc: Xu Liu <xliuprof@google.com>,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
Zecheng Li <zecheng@google.com>
Subject: [PATCH v4 3/9] perf annotate: Track arithmetic instructions on pointers
Date: Mon, 13 Oct 2025 18:16:00 +0000 [thread overview]
Message-ID: <20251013181607.2745653-4-zecheng@google.com> (raw)
In-Reply-To: <20251013181607.2745653-1-zecheng@google.com>
Track the arithmetic operations on registers with pointer types. We
handle only add, sub and lea instructions. The original pointer
information needs to be preserved for getting outermost struct types.
For example, reg0 points to a struct cfs_rq, when we add 0x10 to reg0,
it should preserve the information of struct cfs_rq + 0x10 in the
register instead of a pointer type to the child field at 0x10.
Details:
1. struct type_state_reg now includes an offset, indicating if the
register points to the start or an internal part of its associated
type. This offset is used in mem to reg and reg to stack mem
transfers, and also applied to the final type offset.
2. lea offset(%sp/%fp), reg is now treated as taking the address of a
stack variable. It worked fine in most cases, but an issue with this
approach is the pointer type may not exist.
3. lea offset(%base), reg is handled by moving the type from %base and
adding an offset, similar to an add operation followed by a mov reg
to reg.
4. Non-stack variables from DWARF with non-zero offsets in their
location expressions are now accepted with register offset tracking.
Multi-register addressing modes in LEA are not supported.
Signed-off-by: Zecheng Li <zecheng@google.com>
---
tools/perf/arch/x86/annotate/instructions.c | 137 +++++++++++++++++++-
tools/perf/util/annotate-data.c | 17 ++-
tools/perf/util/annotate-data.h | 6 +
3 files changed, 152 insertions(+), 8 deletions(-)
diff --git a/tools/perf/arch/x86/annotate/instructions.c b/tools/perf/arch/x86/annotate/instructions.c
index 746443e04089..def7729a394c 100644
--- a/tools/perf/arch/x86/annotate/instructions.c
+++ b/tools/perf/arch/x86/annotate/instructions.c
@@ -248,6 +248,7 @@ static void update_insn_state_x86(struct type_state *state,
tsr = &state->regs[state->ret_reg];
tsr->type = type_die;
tsr->kind = TSR_KIND_TYPE;
+ tsr->offset = 0;
tsr->ok = true;
pr_debug_dtp("call [%x] return -> reg%d",
@@ -284,6 +285,7 @@ static void update_insn_state_x86(struct type_state *state,
!strcmp(var_name, "this_cpu_off") &&
tsr->kind == TSR_KIND_CONST) {
tsr->kind = TSR_KIND_PERCPU_BASE;
+ tsr->offset = 0;
tsr->ok = true;
imm_value = tsr->imm_value;
}
@@ -291,6 +293,19 @@ static void update_insn_state_x86(struct type_state *state,
else
return;
+ /* Ignore add to non-pointer or non-const types */
+ if (tsr->kind == TSR_KIND_POINTER ||
+ (dwarf_tag(&tsr->type) == DW_TAG_pointer_type &&
+ src->reg1 != DWARF_REG_PC && tsr->kind == TSR_KIND_TYPE && !dst->mem_ref)) {
+ tsr->offset += imm_value;
+ pr_debug_dtp("add [%x] offset %#"PRIx64" to reg%d",
+ insn_offset, imm_value, dst->reg1);
+ pr_debug_type_name(&tsr->type, tsr->kind);
+ }
+
+ if (tsr->kind == TSR_KIND_CONST)
+ tsr->imm_value += imm_value;
+
if (tsr->kind != TSR_KIND_PERCPU_BASE)
return;
@@ -302,6 +317,7 @@ static void update_insn_state_x86(struct type_state *state,
*/
tsr->type = type_die;
tsr->kind = TSR_KIND_PERCPU_POINTER;
+ tsr->offset = 0;
tsr->ok = true;
pr_debug_dtp("add [%x] percpu %#"PRIx64" -> reg%d",
@@ -311,6 +327,106 @@ static void update_insn_state_x86(struct type_state *state,
return;
}
+ if (!strncmp(dl->ins.name, "sub", 3)) {
+ u64 imm_value = -1ULL;
+
+ if (!has_reg_type(state, dst->reg1))
+ return;
+
+ tsr = &state->regs[dst->reg1];
+ tsr->copied_from = -1;
+
+ if (src->imm)
+ imm_value = src->offset;
+ else if (has_reg_type(state, src->reg1) &&
+ state->regs[src->reg1].kind == TSR_KIND_CONST)
+ imm_value = state->regs[src->reg1].imm_value;
+
+ if (tsr->kind == TSR_KIND_POINTER ||
+ (dwarf_tag(&tsr->type) == DW_TAG_pointer_type &&
+ src->reg1 != DWARF_REG_PC && tsr->kind == TSR_KIND_TYPE && !dst->mem_ref)) {
+ tsr->offset -= imm_value;
+ pr_debug_dtp("sub [%x] offset %#"PRIx64" to reg%d",
+ insn_offset, imm_value, dst->reg1);
+ pr_debug_type_name(&tsr->type, tsr->kind);
+ }
+
+ if (tsr->kind == TSR_KIND_CONST)
+ tsr->imm_value -= imm_value;
+
+ return;
+ }
+
+ if (!strncmp(dl->ins.name, "lea", 3)) {
+ int sreg = src->reg1;
+ struct type_state_reg src_tsr;
+
+ if (!has_reg_type(state, sreg) ||
+ !has_reg_type(state, dst->reg1) ||
+ !src->mem_ref)
+ return;
+
+ src_tsr = state->regs[sreg];
+ tsr = &state->regs[dst->reg1];
+
+ tsr->copied_from = -1;
+ tsr->ok = false;
+
+ /* Case 1: Based on stack pointer or frame pointer */
+ if (sreg == fbreg || sreg == state->stack_reg) {
+ struct type_state_stack *stack;
+ int offset = src->offset - fboff;
+
+ stack = find_stack_state(state, offset);
+ if (!stack)
+ return;
+
+ tsr->type = stack->type;
+ tsr->kind = TSR_KIND_POINTER;
+ tsr->offset = offset - stack->offset;
+ tsr->ok = true;
+
+ if (sreg == fbreg) {
+ pr_debug_dtp("lea [%x] address of -%#x(stack) -> reg%d",
+ insn_offset, -src->offset, dst->reg1);
+ } else {
+ pr_debug_dtp("lea [%x] address of %#x(reg%d) -> reg%d",
+ insn_offset, src->offset, sreg, dst->reg1);
+ }
+
+ pr_debug_type_name(&tsr->type, tsr->kind);
+ }
+ /* Case 2: Based on a register holding a typed pointer */
+ else if (src_tsr.ok && (src_tsr.kind == TSR_KIND_POINTER ||
+ (dwarf_tag(&src_tsr.type) == DW_TAG_pointer_type &&
+ src_tsr.kind == TSR_KIND_TYPE))) {
+
+ if (src_tsr.kind == TSR_KIND_TYPE &&
+ __die_get_real_type(&state->regs[sreg].type, &type_die) == NULL)
+ return;
+
+ if (src_tsr.kind == TSR_KIND_POINTER)
+ type_die = state->regs[sreg].type;
+
+ /* Check if the target type has a member at the new offset */
+ if (die_get_member_type(&type_die,
+ src->offset + src_tsr.offset, &type_die) == NULL)
+ return;
+
+ tsr->type = src_tsr.type;
+ tsr->kind = src_tsr.kind;
+ tsr->offset = src->offset + src_tsr.offset;
+ tsr->ok = true;
+
+ pr_debug_dtp("lea [%x] address of %s%#x(reg%d) -> reg%d",
+ insn_offset, src->offset < 0 ? "-" : "",
+ abs(src->offset), sreg, dst->reg1);
+
+ pr_debug_type_name(&tsr->type, tsr->kind);
+ }
+ return;
+ }
+
if (strncmp(dl->ins.name, "mov", 3))
return;
@@ -345,6 +461,7 @@ static void update_insn_state_x86(struct type_state *state,
if (var_addr == 40) {
tsr->kind = TSR_KIND_CANARY;
+ tsr->offset = 0;
tsr->ok = true;
pr_debug_dtp("mov [%x] stack canary -> reg%d\n",
@@ -361,6 +478,7 @@ static void update_insn_state_x86(struct type_state *state,
tsr->type = type_die;
tsr->kind = TSR_KIND_TYPE;
+ tsr->offset = 0;
tsr->ok = true;
pr_debug_dtp("mov [%x] this-cpu addr=%#"PRIx64" -> reg%d",
@@ -372,6 +490,7 @@ static void update_insn_state_x86(struct type_state *state,
if (src->imm) {
tsr->kind = TSR_KIND_CONST;
tsr->imm_value = src->offset;
+ tsr->offset = 0;
tsr->ok = true;
pr_debug_dtp("mov [%x] imm=%#x -> reg%d\n",
@@ -388,6 +507,7 @@ static void update_insn_state_x86(struct type_state *state,
tsr->type = state->regs[src->reg1].type;
tsr->kind = state->regs[src->reg1].kind;
tsr->imm_value = state->regs[src->reg1].imm_value;
+ tsr->offset = state->regs[src->reg1].offset;
tsr->ok = true;
/* To copy back the variable type later (hopefully) */
@@ -421,12 +541,14 @@ static void update_insn_state_x86(struct type_state *state,
} else if (!stack->compound) {
tsr->type = stack->type;
tsr->kind = stack->kind;
+ tsr->offset = 0;
tsr->ok = true;
} else if (die_get_member_type(&stack->type,
offset - stack->offset,
&type_die)) {
tsr->type = type_die;
tsr->kind = TSR_KIND_TYPE;
+ tsr->offset = 0;
tsr->ok = true;
} else {
tsr->ok = false;
@@ -446,9 +568,10 @@ static void update_insn_state_x86(struct type_state *state,
else if (has_reg_type(state, sreg) && state->regs[sreg].ok &&
state->regs[sreg].kind == TSR_KIND_TYPE &&
die_deref_ptr_type(&state->regs[sreg].type,
- src->offset, &type_die)) {
+ src->offset + state->regs[sreg].offset, &type_die)) {
tsr->type = type_die;
tsr->kind = TSR_KIND_TYPE;
+ tsr->offset = 0;
tsr->ok = true;
pr_debug_dtp("mov [%x] %#x(reg%d) -> reg%d",
@@ -459,9 +582,10 @@ static void update_insn_state_x86(struct type_state *state,
else if (has_reg_type(state, sreg) && state->regs[sreg].ok &&
state->regs[sreg].kind == TSR_KIND_POINTER &&
die_get_member_type(&state->regs[sreg].type,
- src->offset, &type_die)) {
+ src->offset + state->regs[sreg].offset, &type_die)) {
tsr->type = state->regs[sreg].type;
tsr->kind = TSR_KIND_TYPE;
+ tsr->offset = src->offset + state->regs[sreg].offset;
tsr->ok = true;
pr_debug_dtp("mov [%x] addr %#x(reg%d) -> reg%d",
@@ -486,6 +610,7 @@ static void update_insn_state_x86(struct type_state *state,
tsr->type = type_die;
tsr->kind = TSR_KIND_TYPE;
+ tsr->offset = 0;
tsr->ok = true;
pr_debug_dtp("mov [%x] global addr=%"PRIx64" -> reg%d",
@@ -517,6 +642,7 @@ static void update_insn_state_x86(struct type_state *state,
die_get_member_type(&type_die, offset, &type_die)) {
tsr->type = type_die;
tsr->kind = TSR_KIND_TYPE;
+ tsr->offset = 0;
tsr->ok = true;
if (src->multi_regs) {
@@ -539,6 +665,7 @@ static void update_insn_state_x86(struct type_state *state,
src->offset, &type_die)) {
tsr->type = type_die;
tsr->kind = TSR_KIND_TYPE;
+ tsr->offset = 0;
tsr->ok = true;
pr_debug_dtp("mov [%x] pointer %#x(reg%d) -> reg%d",
@@ -561,6 +688,7 @@ static void update_insn_state_x86(struct type_state *state,
&var_name, &offset) &&
!strcmp(var_name, "__per_cpu_offset")) {
tsr->kind = TSR_KIND_PERCPU_BASE;
+ tsr->offset = 0;
tsr->ok = true;
pr_debug_dtp("mov [%x] percpu base reg%d\n",
@@ -609,6 +737,11 @@ static void update_insn_state_x86(struct type_state *state,
pr_debug_dtp("mov [%x] reg%d -> %#x(reg%d)",
insn_offset, src->reg1, offset, dst->reg1);
}
+ if (tsr->offset != 0) {
+ pr_debug_dtp(" reg%d offset %#x ->",
+ src->reg1, tsr->offset);
+ }
+
pr_debug_type_name(&tsr->type, tsr->kind);
}
/*
diff --git a/tools/perf/util/annotate-data.c b/tools/perf/util/annotate-data.c
index 48f3bf20070f..4204a7956ee5 100644
--- a/tools/perf/util/annotate-data.c
+++ b/tools/perf/util/annotate-data.c
@@ -905,7 +905,7 @@ static void update_var_state(struct type_state *state, struct data_loc_info *dlo
insn_offset, -offset);
}
pr_debug_type_name(&mem_die, TSR_KIND_TYPE);
- } else if (has_reg_type(state, var->reg) && var->offset == 0) {
+ } else if (has_reg_type(state, var->reg)) {
struct type_state_reg *reg;
Dwarf_Die orig_type;
@@ -921,6 +921,7 @@ static void update_var_state(struct type_state *state, struct data_loc_info *dlo
!is_better_type(®->type, &mem_die))
continue;
+ reg->offset = -var->offset;
reg->type = mem_die;
reg->kind = TSR_KIND_POINTER;
reg->ok = true;
@@ -932,13 +933,17 @@ static void update_var_state(struct type_state *state, struct data_loc_info *dlo
}
orig_type = reg->type;
-
+ /*
+ * var->offset + reg value is the beginning of the struct
+ * reg->offset is the offset the reg points
+ */
+ reg->offset = -var->offset;
reg->type = mem_die;
reg->kind = TSR_KIND_TYPE;
reg->ok = true;
- pr_debug_dtp("var [%"PRIx64"] reg%d",
- insn_offset, var->reg);
+ pr_debug_dtp("var [%"PRIx64"] reg%d offset %x",
+ insn_offset, var->reg, var->offset);
pr_debug_type_name(&mem_die, TSR_KIND_TYPE);
/*
@@ -1126,7 +1131,7 @@ static enum type_match_result check_matching_type(struct type_state *state,
if (__die_get_real_type(&state->regs[reg].type, type_die) == NULL)
return PERF_TMR_NO_POINTER;
- dloc->type_offset = dloc->op->offset;
+ dloc->type_offset = dloc->op->offset + state->regs[reg].offset;
if (dwarf_tag(type_die) == DW_TAG_typedef)
die_get_real_type(type_die, &sized_type);
@@ -1155,7 +1160,7 @@ static enum type_match_result check_matching_type(struct type_state *state,
*/
*type_die = state->regs[reg].type;
- dloc->type_offset = dloc->op->offset;
+ dloc->type_offset = dloc->op->offset + state->regs[reg].offset;
/* Get the size of the actual type */
if (dwarf_aggregate_size(type_die, &size) < 0 ||
diff --git a/tools/perf/util/annotate-data.h b/tools/perf/util/annotate-data.h
index 026783442056..14655b76db65 100644
--- a/tools/perf/util/annotate-data.h
+++ b/tools/perf/util/annotate-data.h
@@ -174,6 +174,12 @@ extern struct annotated_data_stat ann_data_stat;
struct type_state_reg {
Dwarf_Die type;
u32 imm_value;
+ /*
+ * The offset within the struct that the register points to.
+ * A value of 0 means the register points to the beginning.
+ * type_offset = op->offset + reg->offset
+ */
+ s32 offset;
bool ok;
bool caller_saved;
u8 kind;
--
2.51.0.788.g6d19910ace-goog
next prev parent reply other threads:[~2025-10-13 18:16 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-13 18:15 [PATCH v4 0/9] perf tools: Some improvements on data type profiler Zecheng Li
2025-10-13 18:15 ` [PATCH v4 1/9] perf annotate: Skip annotating data types to lea instructions Zecheng Li
2025-10-13 18:15 ` [PATCH v4 2/9] perf annotate: Track address registers via TSR_KIND_POINTER Zecheng Li
2025-10-13 18:16 ` Zecheng Li [this message]
2025-10-13 18:16 ` [PATCH v4 4/9] perf annotate: Save pointer offset in stack state Zecheng Li
2025-10-13 18:16 ` [PATCH v4 5/9] perf annotate: Invalidate register states for untracked instructions Zecheng Li
2025-10-13 18:16 ` [PATCH v4 6/9] perf dwarf-aux: Skip check_variable for die_find_variable_by_reg Zecheng Li
2025-10-13 18:16 ` [PATCH v4 7/9] perf dwarf-aux: Preserve typedefs in match_var_offset Zecheng Li
2025-10-13 18:16 ` [PATCH v4 8/9] perf annotate: Improve type comparison from different scopes Zecheng Li
2025-10-13 18:16 ` [PATCH v4 9/9] perf dwarf-aux: Support DW_OP_piece expressions Zecheng Li
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