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i#6508 context switches: Add invariant checker unit tests
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Adds some invariant checker unit tests for kernel context switch traces.

Adjusts some invariant checks to account for kernel context switch traces.

Issue: #6508
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@abhinav92003
abhinav92003 committed Mar 28, 2024
1 parent 62af632 commit 518f32f
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Showing 3 changed files with 96 additions and 5 deletions.
69 changes: 68 additions & 1 deletion clients/drcachesim/tests/invariant_checker_test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2941,6 +2941,72 @@ check_exit_found(void)
return true;
}

bool
check_kernel_context_switch_trace(void)
{
std::cerr << "Testing kernel context switch traces\n";
{
std::vector<memref_t> memrefs = {
gen_marker(TID_A, TRACE_MARKER_TYPE_CACHE_LINE_SIZE, 64),
gen_marker(TID_A, TRACE_MARKER_TYPE_PAGE_SIZE, 4096),
gen_marker(TID_A, TRACE_MARKER_TYPE_VERSION, TRACE_ENTRY_VERSION_BRANCH_INFO),
gen_instr(TID_A, /*pc=*/1),
gen_marker(TID_A, TRACE_MARKER_TYPE_CONTEXT_SWITCH_START, 0),
gen_instr(TID_A, /*pc=*/10),
gen_instr(TID_A, /*pc=*/11),
gen_marker(TID_A, TRACE_MARKER_TYPE_CONTEXT_SWITCH_END, 0),
gen_instr(TID_A, /*pc=*/2),
gen_exit(TID_A),
};
if (!run_checker(memrefs, false))
return false;
}
{
std::vector<memref_t> memrefs = {
gen_marker(TID_A, TRACE_MARKER_TYPE_CACHE_LINE_SIZE, 64),
gen_marker(TID_A, TRACE_MARKER_TYPE_PAGE_SIZE, 4096),
gen_marker(TID_A, TRACE_MARKER_TYPE_VERSION, TRACE_ENTRY_VERSION_BRANCH_INFO),
gen_instr(TID_A, /*pc=*/1),
gen_marker(TID_A, TRACE_MARKER_TYPE_CONTEXT_SWITCH_START, 0),
gen_instr(TID_A, /*pc=*/10),
gen_instr(TID_A, /*pc=*/11),
gen_marker(TID_A, TRACE_MARKER_TYPE_CONTEXT_SWITCH_END, 0),
gen_instr(TID_A, /*pc=*/3),
gen_exit(TID_A),
};
if (!run_checker(memrefs, true,
{ "Non-explicit control flow has no marker", TID_A,
/*ref_ordinal=*/9, /*last_timestamp=*/0,
/*instrs_since_last_timestamp=*/4 },
"Failed to catch PC discontinuity after context switch trace")) {
return false;
}
}
{
std::vector<memref_t> memrefs = {
gen_marker(TID_A, TRACE_MARKER_TYPE_CACHE_LINE_SIZE, 64),
gen_marker(TID_A, TRACE_MARKER_TYPE_PAGE_SIZE, 4096),
gen_marker(TID_A, TRACE_MARKER_TYPE_VERSION, TRACE_ENTRY_VERSION_BRANCH_INFO),
gen_instr(TID_A, /*pc=*/1),
gen_marker(TID_A, TRACE_MARKER_TYPE_CONTEXT_SWITCH_START, 0),
gen_instr(TID_A, /*pc=*/10),
gen_instr(TID_A, /*pc=*/12),
gen_marker(TID_A, TRACE_MARKER_TYPE_CONTEXT_SWITCH_END, 0),
gen_instr(TID_A, /*pc=*/2),
gen_exit(TID_A),
};
if (!run_checker(
memrefs, true,
{ "Non-explicit control flow has no marker", TID_A,
/*ref_ordinal=*/7, /*last_timestamp=*/0,
/*instrs_since_last_timestamp=*/3 },
"Failed to catch PC discontinuity inside context switch trace")) {
return false;
}
}
return true;
}

bool
check_kernel_syscall_trace(void)
{
Expand Down Expand Up @@ -3377,7 +3443,8 @@ test_main(int argc, const char *argv[])
check_branch_decoration() && check_filter_endpoint() &&
check_timestamps_increase_monotonically() &&
check_read_write_records_match_operands() && check_exit_found() &&
check_kernel_syscall_trace() && check_has_instructions()) {
check_kernel_syscall_trace() && check_has_instructions() &&
check_kernel_context_switch_trace()) {
std::cerr << "invariant_checker_test passed\n";
return 0;
}
Expand Down
30 changes: 26 additions & 4 deletions clients/drcachesim/tools/invariant_checker.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -536,12 +536,29 @@ invariant_checker_t::parallel_shard_memref(void *shard_data, const memref_t &mem
shard->pre_syscall_trace_instr_ = {};
}
}
if (memref.marker.type == TRACE_TYPE_MARKER &&
memref.marker.marker_type == TRACE_MARKER_TYPE_CONTEXT_SWITCH_START) {
report_if_false(shard, !shard->between_kernel_context_switch_markers_,
"Nested kernel context switch traces are not expected");
shard->pre_context_switch_trace_instr_ = shard->prev_instr_;
shard->between_kernel_context_switch_markers_ = true;
}
if (memref.marker.type == TRACE_TYPE_MARKER &&
memref.marker.marker_type == TRACE_MARKER_TYPE_CONTEXT_SWITCH_END) {
report_if_false(shard, shard->between_kernel_context_switch_markers_,
"Found kernel context switch trace end without start");
shard->between_kernel_context_switch_markers_ = false;
// For future checks, pretend that the previous instr was the instr just
// before the context switch trace start.
if (shard->pre_context_switch_trace_instr_.memref.instr.addr > 0) {
shard->prev_instr_ = shard->pre_context_switch_trace_instr_;
shard->pre_context_switch_trace_instr_ = {};
}
}
if (!is_a_unit_test(shard)) {
// XXX: between_kernel_syscall_trace_markers_ does not track the
// TRACE_MARKER_TYPE_CONTEXT_SWITCH_* markers. If the invariant checker is run
// with dynamic injection of context switch sequences this will throw an error.
report_if_false(shard,
shard->between_kernel_syscall_trace_markers_ ==
(shard->between_kernel_syscall_trace_markers_ ||
shard->between_kernel_context_switch_markers_) ==
shard->stream->is_record_kernel(),
"Stream is_record_kernel() inaccurate");
}
Expand Down Expand Up @@ -1353,6 +1370,11 @@ invariant_checker_t::check_for_pc_discontinuity(
(shard->prev_entry_.marker.type == TRACE_TYPE_MARKER &&
shard->prev_entry_.marker.marker_type ==
TRACE_MARKER_TYPE_SYSCALL_TRACE_START)) ||
// First instr of kernel context switch trace.
(shard->between_kernel_context_switch_markers_ &&
(shard->prev_entry_.marker.type == TRACE_TYPE_MARKER &&
shard->prev_entry_.marker.marker_type ==
TRACE_MARKER_TYPE_CONTEXT_SWITCH_START)) ||
// String loop.
(prev_instr_trace_pc == cur_pc &&
(cur_memref_info.memref.instr.type == TRACE_TYPE_INSTR_NO_FETCH ||
Expand Down
2 changes: 2 additions & 0 deletions clients/drcachesim/tools/invariant_checker.h
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Original file line number Diff line number Diff line change
Expand Up @@ -230,7 +230,9 @@ class invariant_checker_t : public analysis_tool_t {
int expected_read_records_ = 0;
int expected_write_records_ = 0;
bool between_kernel_syscall_trace_markers_ = false;
bool between_kernel_context_switch_markers_ = false;
instr_info_t pre_syscall_trace_instr_;
instr_info_t pre_context_switch_trace_instr_;
// Relevant when -no_abort_on_invariant_error.
uint64_t error_count_ = 0;
};
Expand Down

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