Increase BPFTRACE_MAX_STRLEN from 64 to 1024

Now that we support big-X and printing big-X's, we can increase the default size to 1024. Note that this will break anyone assigning a default string to a scratch variable. However, they have a couple potential remediations: 1. Assign it to a map instead 2. Save the str() call for the print()/printf() argument 3. Clamp the string size These options are all pretty easy and cover all the use cases I can think of. And given big strings are something users have been asking about for years, I think the relatively small pain is a worthwhile price.
bpftrace · Aug 7, 2024 · eb734db · eb734db
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -30,6 +30,8 @@ and this project adheres to
   - [#3249](https://github.com/bpftrace/bpftrace/pull/3249)
 - Faster map access for keyless maps by using BPF_MAP_TYPE_ARRAY
   - [#3300](https://github.com/bpftrace/bpftrace/pull/3300)
+- Increase default string size from 64 to 1024
+  - [#3371](https://github.com/bpftrace/bpftrace/pull/3371)
 #### Deprecated
 #### Removed
 - Remove the `-dd` CLI option

diff --git a/man/adoc/bpftrace.adoc b/man/adoc/bpftrace.adoc
@@ -3443,15 +3443,12 @@ system.
 
 === max_strlen
 
-Default: 64
+Default: 1024
 
-Number of bytes allocated on the BPF stack for the string returned by str().
-Make this larger if you wish to read bigger strings with str().
-Beware that the BPF stack is small (512 bytes), and that you pay the toll again inside printf() (whilst
-it composes a perf event output buffer).
-So in practice you can only grow this to about 200 bytes.
+The maximum length (in bytes) for values created by `str()`, `buf()` and `path()`.
 
-Support for even larger strings is being discussed: https://github.com/bpftrace/bpftrace/issues/305.
+This limit is necessary because BPF requires the size of all dynamically-read strings (and similar) to be declared up front. This is the size for all strings (and similar) in bpftrace unless specified at the call site.
+There is no artificial limit on what you can tune this to. But you may be wasting resources (memory and cpu) if you make this too high.
 
 === max_type_res_iterations
 

diff --git a/src/ast/passes/semantic_analyser.cpp b/src/ast/passes/semantic_analyser.cpp
@@ -2678,6 +2678,22 @@ void SemanticAnalyser::visit(AssignVarStatement &assignment)
     if (ty == Type::none)
       LOG(ERROR, assignment.expr->loc, err_)
           << "Invalid expression for assignment: " << ty;
+
+    // Scratch variables are on the BPF stack, which is only 512 bytes at time
+    // of writing, so large values do not fit on there. 200 is a ballpark of
+    // what probably won't work.
+    auto expr_size = assignTy.GetSize();
+    if (expr_size > 200) {
+      LOG(ERROR, assignment.loc, err_)
+          << "Value is too big "
+          << "(" << expr_size << " bytes) for the stack. "
+          << "Try reducing its size, storing it in a map, or creating it in "
+             "argument position to a helper call.\n\n"
+          << "Examples:\n"
+          << "    `$s = str(..);` => `$s = str(.., 32);`\n"
+          << "    `$s = str(..);` => `@s = str(..);`\n"
+          << "    `$s = str(..); print($s);` => `print(str(..));`\n\n";
+    }
   }
 }
 

diff --git a/src/config.cpp b/src/config.cpp
@@ -19,7 +19,7 @@ Config::Config(bool has_cmd)
     { ConfigKeyInt::max_cat_bytes, { .value = (uint64_t)10240 } },
     { ConfigKeyInt::max_map_keys, { .value = (uint64_t)4096 } },
     { ConfigKeyInt::max_probes, { .value = (uint64_t)512 } },
-    { ConfigKeyInt::max_strlen, { .value = (uint64_t)64 } },
+    { ConfigKeyInt::max_strlen, { .value = (uint64_t)1024 } },
     { ConfigKeyInt::max_type_res_iterations, { .value = (uint64_t)0 } },
     { ConfigKeyInt::perf_rb_pages, { .value = (uint64_t)64 } },
     { ConfigKeyStackMode::default_, { .value = StackMode::bpftrace } },

diff --git a/src/main.cpp b/src/main.cpp
@@ -134,7 +134,7 @@ void usage()
   std::cerr << "    BPFTRACE_MAX_CAT_BYTES            [default: 10k] maximum bytes read by cat builtin" << std::endl;
   std::cerr << "    BPFTRACE_MAX_MAP_KEYS             [default: 4096] max keys in a map" << std::endl;
   std::cerr << "    BPFTRACE_MAX_PROBES               [default: 512] max number of probes" << std::endl;
-  std::cerr << "    BPFTRACE_MAX_STRLEN               [default: 64] bytes on BPF stack per str()" << std::endl;
+  std::cerr << "    BPFTRACE_MAX_STRLEN               [default: 1024] bytes on BPF stack per str()" << std::endl;
   std::cerr << "    BPFTRACE_MAX_TYPE_RES_ITERATIONS  [default: 0] number of levels of nested field accesses for tracepoint args" << std::endl;
   std::cerr << "    BPFTRACE_PERF_RB_PAGES            [default: 64] pages per CPU to allocate for ring buffer" << std::endl;
   std::cerr << "    BPFTRACE_STACK_MODE               [default: bpftrace] Output format for ustack and kstack builtins" << std::endl;

diff --git a/tests/codegen/llvm/call_buf_implicit_size.ll b/tests/codegen/llvm/call_buf_implicit_size.ll
@@ -117,9 +117,9 @@ attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: write) }
 !47 = !DISubrange(count: 6, lowerBound: 0)
 !48 = !DIDerivedType(tag: DW_TAG_member, name: "value", scope: !2, file: !2, baseType: !49, size: 64, offset: 192)
 !49 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !50, size: 64)
-!50 = !DICompositeType(tag: DW_TAG_array_type, baseType: !22, size: 512, elements: !51)
+!50 = !DICompositeType(tag: DW_TAG_array_type, baseType: !22, size: 8192, elements: !51)
 !51 = !{!52}
-!52 = !DISubrange(count: 64, lowerBound: 0)
+!52 = !DISubrange(count: 1024, lowerBound: 0)
 !53 = !DIGlobalVariableExpression(var: !54, expr: !DIExpression())
 !54 = distinct !DIGlobalVariable(name: "event_loss_counter", linkageName: "global", scope: !2, file: !2, type: !55, isLocal: false, isDefinition: true)
 !55 = !DICompositeType(tag: DW_TAG_structure_type, scope: !2, file: !2, size: 256, elements: !56)

diff --git a/tests/codegen/llvm/call_buf_size_literal.ll b/tests/codegen/llvm/call_buf_size_literal.ll
@@ -113,9 +113,9 @@ attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: write) }
 !47 = !DISubrange(count: 6, lowerBound: 0)
 !48 = !DIDerivedType(tag: DW_TAG_member, name: "value", scope: !2, file: !2, baseType: !49, size: 64, offset: 192)
 !49 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !50, size: 64)
-!50 = !DICompositeType(tag: DW_TAG_array_type, baseType: !22, size: 512, elements: !51)
+!50 = !DICompositeType(tag: DW_TAG_array_type, baseType: !22, size: 8192, elements: !51)
 !51 = !{!52}
-!52 = !DISubrange(count: 64, lowerBound: 0)
+!52 = !DISubrange(count: 1024, lowerBound: 0)
 !53 = !DIGlobalVariableExpression(var: !54, expr: !DIExpression())
 !54 = distinct !DIGlobalVariable(name: "event_loss_counter", linkageName: "global", scope: !2, file: !2, type: !55, isLocal: false, isDefinition: true)
 !55 = !DICompositeType(tag: DW_TAG_structure_type, scope: !2, file: !2, size: 256, elements: !56)

diff --git a/tests/codegen/llvm/call_buf_size_nonliteral.ll b/tests/codegen/llvm/call_buf_size_nonliteral.ll
@@ -7,7 +7,7 @@ target triple = "bpf-pc-linux"
 %"struct map_t.0" = type { ptr, ptr }
 %"struct map_t.1" = type { ptr, ptr, ptr, ptr }
 %"struct map_t.2" = type { ptr, ptr, ptr, ptr }
-%buffer_60_t = type <{ i32, [60 x i8] }>
+%buffer_1020_t = type <{ i32, [1020 x i8] }>
 
 @LICENSE = global [4 x i8] c"GPL\00", section "license"
 @AT_x = dso_local global %"struct map_t" zeroinitializer, section ".maps", !dbg !0
@@ -24,8 +24,8 @@ entry:
   %lookup_str_key = alloca i32, align 4
   %1 = getelementptr i64, ptr %0, i64 13
   %arg1 = load volatile i64, ptr %1, align 8
-  %length.cmp = icmp ule i64 %arg1, 60
-  %length.select = select i1 %length.cmp, i64 %arg1, i64 60
+  %length.cmp = icmp ule i64 %arg1, 1020
+  %length.select = select i1 %length.cmp, i64 %arg1, i64 1020
   call void @llvm.lifetime.start.p0(i64 -1, ptr %lookup_str_key)
   store i32 0, ptr %lookup_str_key, align 4
   %lookup_str_map = call ptr inttoptr (i64 1 to ptr)(ptr @str_buffer, ptr %lookup_str_key)
@@ -37,14 +37,14 @@ lookup_str_failure:                               ; preds = %entry
   ret i64 0
 
 lookup_str_merge:                                 ; preds = %entry
-  %2 = getelementptr %buffer_60_t, ptr %lookup_str_map, i32 0, i32 0
+  %2 = getelementptr %buffer_1020_t, ptr %lookup_str_map, i32 0, i32 0
   %3 = trunc i64 %length.select to i32
   store i32 %3, ptr %2, align 4
-  %4 = getelementptr %buffer_60_t, ptr %lookup_str_map, i32 0, i32 1
-  call void @llvm.memset.p0.i64(ptr align 1 %4, i8 0, i64 60, i1 false)
+  %4 = getelementptr %buffer_1020_t, ptr %lookup_str_map, i32 0, i32 1
+  %probe_read_kernel = call i64 inttoptr (i64 113 to ptr)(ptr %4, i32 1020, ptr null)
   %5 = getelementptr i64, ptr %0, i64 14
   %arg0 = load volatile i64, ptr %5, align 8
-  %probe_read_kernel = call i64 inttoptr (i64 113 to ptr)(ptr %4, i32 %3, i64 %arg0)
+  %probe_read_kernel1 = call i64 inttoptr (i64 113 to ptr)(ptr %4, i32 %3, i64 %arg0)
   call void @llvm.lifetime.start.p0(i64 -1, ptr %"@x_key")
   store i64 0, ptr %"@x_key", align 8
   %update_elem = call i64 inttoptr (i64 2 to ptr)(ptr @AT_x, ptr %"@x_key", ptr %lookup_str_map, i64 0)
@@ -58,12 +58,8 @@ declare void @llvm.lifetime.start.p0(i64 immarg %0, ptr nocapture %1) #1
 ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 declare void @llvm.lifetime.end.p0(i64 immarg %0, ptr nocapture %1) #1
 
-; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: write)
-declare void @llvm.memset.p0.i64(ptr nocapture writeonly %0, i8 %1, i64 %2, i1 immarg %3) #2
-
 attributes #0 = { nounwind }
 attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: write) }
 
 !llvm.dbg.cu = !{!55}
 !llvm.module.flags = !{!57}
@@ -89,10 +85,10 @@ attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: write) }
 !18 = !DIBasicType(name: "int32", size: 32, encoding: DW_ATE_signed)
 !19 = !DIDerivedType(tag: DW_TAG_member, name: "value", scope: !2, file: !2, baseType: !20, size: 64, offset: 192)
 !20 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !21, size: 64)
-!21 = !DICompositeType(tag: DW_TAG_array_type, baseType: !22, size: 512, elements: !23)
+!21 = !DICompositeType(tag: DW_TAG_array_type, baseType: !22, size: 8192, elements: !23)
 !22 = !DIBasicType(name: "int8", size: 8, encoding: DW_ATE_signed)
 !23 = !{!24}
-!24 = !DISubrange(count: 64, lowerBound: 0)
+!24 = !DISubrange(count: 1024, lowerBound: 0)
 !25 = !DIGlobalVariableExpression(var: !26, expr: !DIExpression())
 !26 = distinct !DIGlobalVariable(name: "ringbuf", linkageName: "global", scope: !2, file: !2, type: !27, isLocal: false, isDefinition: true)
 !27 = !DICompositeType(tag: DW_TAG_structure_type, scope: !2, file: !2, size: 128, elements: !28)

diff --git a/tests/codegen/llvm/call_str.ll b/tests/codegen/llvm/call_str.ll
@@ -32,10 +32,10 @@ lookup_str_failure:                               ; preds = %entry
   ret i64 0
 
 lookup_str_merge:                                 ; preds = %entry
-  call void @llvm.memset.p0.i64(ptr align 1 %lookup_str_map, i8 0, i64 64, i1 false)
+  %probe_read_kernel = call i64 inttoptr (i64 113 to ptr)(ptr %lookup_str_map, i32 1024, ptr null)
   %1 = getelementptr i64, ptr %0, i64 14
   %arg0 = load volatile i64, ptr %1, align 8
-  %probe_read_kernel_str = call i64 inttoptr (i64 115 to ptr)(ptr %lookup_str_map, i32 64, i64 %arg0)
+  %probe_read_kernel_str = call i64 inttoptr (i64 115 to ptr)(ptr %lookup_str_map, i32 1024, i64 %arg0)
   call void @llvm.lifetime.start.p0(i64 -1, ptr %"@x_key")
   store i64 0, ptr %"@x_key", align 8
   %update_elem = call i64 inttoptr (i64 2 to ptr)(ptr @AT_x, ptr %"@x_key", ptr %lookup_str_map, i64 0)
@@ -49,12 +49,8 @@ declare void @llvm.lifetime.start.p0(i64 immarg %0, ptr nocapture %1) #1
 ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 declare void @llvm.lifetime.end.p0(i64 immarg %0, ptr nocapture %1) #1
 
-; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: write)
-declare void @llvm.memset.p0.i64(ptr nocapture writeonly %0, i8 %1, i64 %2, i1 immarg %3) #2
-
 attributes #0 = { nounwind }
 attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: write) }
 
 !llvm.dbg.cu = !{!55}
 !llvm.module.flags = !{!57}
@@ -80,10 +76,10 @@ attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: write) }
 !18 = !DIBasicType(name: "int32", size: 32, encoding: DW_ATE_signed)
 !19 = !DIDerivedType(tag: DW_TAG_member, name: "value", scope: !2, file: !2, baseType: !20, size: 64, offset: 192)
 !20 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !21, size: 64)
-!21 = !DICompositeType(tag: DW_TAG_array_type, baseType: !22, size: 512, elements: !23)
+!21 = !DICompositeType(tag: DW_TAG_array_type, baseType: !22, size: 8192, elements: !23)
 !22 = !DIBasicType(name: "int8", size: 8, encoding: DW_ATE_signed)
 !23 = !{!24}
-!24 = !DISubrange(count: 64, lowerBound: 0)
+!24 = !DISubrange(count: 1024, lowerBound: 0)
 !25 = !DIGlobalVariableExpression(var: !26, expr: !DIExpression())
 !26 = distinct !DIGlobalVariable(name: "ringbuf", linkageName: "global", scope: !2, file: !2, type: !27, isLocal: false, isDefinition: true)
 !27 = !DICompositeType(tag: DW_TAG_structure_type, scope: !2, file: !2, size: 128, elements: !28)

diff --git a/tests/codegen/llvm/call_str_2_expr.ll b/tests/codegen/llvm/call_str_2_expr.ll
@@ -24,8 +24,8 @@ entry:
   %1 = getelementptr i64, ptr %0, i64 13
   %arg1 = load volatile i64, ptr %1, align 8
   %2 = add i64 %arg1, 1
-  %str.min.cmp = icmp ule i64 %2, 64
-  %str.min.select = select i1 %str.min.cmp, i64 %2, i64 64
+  %str.min.cmp = icmp ule i64 %2, 1024
+  %str.min.select = select i1 %str.min.cmp, i64 %2, i64 1024
   call void @llvm.lifetime.start.p0(i64 -1, ptr %lookup_str_key)
   store i32 0, ptr %lookup_str_key, align 4
   %lookup_str_map = call ptr inttoptr (i64 1 to ptr)(ptr @str_buffer, ptr %lookup_str_key)
@@ -37,7 +37,7 @@ lookup_str_failure:                               ; preds = %entry
   ret i64 0
 
 lookup_str_merge:                                 ; preds = %entry
-  call void @llvm.memset.p0.i64(ptr align 1 %lookup_str_map, i8 0, i64 64, i1 false)
+  %probe_read_kernel = call i64 inttoptr (i64 113 to ptr)(ptr %lookup_str_map, i32 1024, ptr null)
   %3 = getelementptr i64, ptr %0, i64 14
   %arg0 = load volatile i64, ptr %3, align 8
   %4 = trunc i64 %str.min.select to i32
@@ -55,12 +55,8 @@ declare void @llvm.lifetime.start.p0(i64 immarg %0, ptr nocapture %1) #1
 ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 declare void @llvm.lifetime.end.p0(i64 immarg %0, ptr nocapture %1) #1
 
-; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: write)
-declare void @llvm.memset.p0.i64(ptr nocapture writeonly %0, i8 %1, i64 %2, i1 immarg %3) #2
-
 attributes #0 = { nounwind }
 attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: write) }
 
 !llvm.dbg.cu = !{!55}
 !llvm.module.flags = !{!57}
@@ -86,10 +82,10 @@ attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: write) }
 !18 = !DIBasicType(name: "int32", size: 32, encoding: DW_ATE_signed)
 !19 = !DIDerivedType(tag: DW_TAG_member, name: "value", scope: !2, file: !2, baseType: !20, size: 64, offset: 192)
 !20 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !21, size: 64)
-!21 = !DICompositeType(tag: DW_TAG_array_type, baseType: !22, size: 512, elements: !23)
+!21 = !DICompositeType(tag: DW_TAG_array_type, baseType: !22, size: 8192, elements: !23)
 !22 = !DIBasicType(name: "int8", size: 8, encoding: DW_ATE_signed)
 !23 = !{!24}
-!24 = !DISubrange(count: 64, lowerBound: 0)
+!24 = !DISubrange(count: 1024, lowerBound: 0)
 !25 = !DIGlobalVariableExpression(var: !26, expr: !DIExpression())
 !26 = distinct !DIGlobalVariable(name: "ringbuf", linkageName: "global", scope: !2, file: !2, type: !27, isLocal: false, isDefinition: true)
 !27 = !DICompositeType(tag: DW_TAG_structure_type, scope: !2, file: !2, size: 128, elements: !28)

diff --git a/tests/codegen/llvm/call_str_2_lit.ll b/tests/codegen/llvm/call_str_2_lit.ll
@@ -32,7 +32,7 @@ lookup_str_failure:                               ; preds = %entry
   ret i64 0
 
 lookup_str_merge:                                 ; preds = %entry
-  call void @llvm.memset.p0.i64(ptr align 1 %lookup_str_map, i8 0, i64 64, i1 false)
+  %probe_read_kernel = call i64 inttoptr (i64 113 to ptr)(ptr %lookup_str_map, i32 1024, ptr null)
   %1 = getelementptr i64, ptr %0, i64 14
   %arg0 = load volatile i64, ptr %1, align 8
   %probe_read_kernel_str = call i64 inttoptr (i64 115 to ptr)(ptr %lookup_str_map, i32 7, i64 %arg0)
@@ -49,12 +49,8 @@ declare void @llvm.lifetime.start.p0(i64 immarg %0, ptr nocapture %1) #1
 ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 declare void @llvm.lifetime.end.p0(i64 immarg %0, ptr nocapture %1) #1
 
-; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: write)
-declare void @llvm.memset.p0.i64(ptr nocapture writeonly %0, i8 %1, i64 %2, i1 immarg %3) #2
-
 attributes #0 = { nounwind }
 attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: write) }
 
 !llvm.dbg.cu = !{!58}
 !llvm.module.flags = !{!60}
@@ -107,9 +103,9 @@ attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: write) }
 !45 = !DICompositeType(tag: DW_TAG_array_type, baseType: !8, size: 192, elements: !23)
 !46 = !DIDerivedType(tag: DW_TAG_member, name: "value", scope: !2, file: !2, baseType: !47, size: 64, offset: 192)
 !47 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !48, size: 64)
-!48 = !DICompositeType(tag: DW_TAG_array_type, baseType: !22, size: 512, elements: !49)
+!48 = !DICompositeType(tag: DW_TAG_array_type, baseType: !22, size: 8192, elements: !49)
 !49 = !{!50}
-!50 = !DISubrange(count: 64, lowerBound: 0)
+!50 = !DISubrange(count: 1024, lowerBound: 0)
 !51 = !DIGlobalVariableExpression(var: !52, expr: !DIExpression())
 !52 = distinct !DIGlobalVariable(name: "event_loss_counter", linkageName: "global", scope: !2, file: !2, type: !53, isLocal: false, isDefinition: true)
 !53 = !DICompositeType(tag: DW_TAG_structure_type, scope: !2, file: !2, size: 256, elements: !54)

diff --git a/tests/codegen/llvm/optional_positional_parameter.ll b/tests/codegen/llvm/optional_positional_parameter.ll
@@ -44,12 +44,12 @@ lookup_str_failure:                               ; preds = %entry
   ret i64 0
 
 lookup_str_merge:                                 ; preds = %entry
-  call void @llvm.memset.p0.i64(ptr align 1 %lookup_str_map, i8 0, i64 64, i1 false)
+  %probe_read_kernel = call i64 inttoptr (i64 113 to ptr)(ptr %lookup_str_map, i32 1024, ptr null)
   call void @llvm.lifetime.start.p0(i64 -1, ptr %str)
   call void @llvm.memset.p0.i64(ptr align 1 %str, i8 0, i64 1, i1 false)
   store [1 x i8] zeroinitializer, ptr %str, align 1
   %1 = ptrtoint ptr %str to i64
-  %probe_read_kernel_str = call i64 inttoptr (i64 115 to ptr)(ptr %lookup_str_map, i32 64, i64 %1)
+  %probe_read_kernel_str = call i64 inttoptr (i64 115 to ptr)(ptr %lookup_str_map, i32 1024, i64 %1)
   call void @llvm.lifetime.end.p0(i64 -1, ptr %str)
   call void @llvm.lifetime.start.p0(i64 -1, ptr %"@y_key")
   store i64 0, ptr %"@y_key", align 8
@@ -102,10 +102,10 @@ attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: write) }
 !25 = !{!5, !11, !16, !26}
 !26 = !DIDerivedType(tag: DW_TAG_member, name: "value", scope: !2, file: !2, baseType: !27, size: 64, offset: 192)
 !27 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !28, size: 64)
-!28 = !DICompositeType(tag: DW_TAG_array_type, baseType: !29, size: 512, elements: !30)
+!28 = !DICompositeType(tag: DW_TAG_array_type, baseType: !29, size: 8192, elements: !30)
 !29 = !DIBasicType(name: "int8", size: 8, encoding: DW_ATE_signed)
 !30 = !{!31}
-!31 = !DISubrange(count: 64, lowerBound: 0)
+!31 = !DISubrange(count: 1024, lowerBound: 0)
 !32 = !DIGlobalVariableExpression(var: !33, expr: !DIExpression())
 !33 = distinct !DIGlobalVariable(name: "ringbuf", linkageName: "global", scope: !2, file: !2, type: !34, isLocal: false, isDefinition: true)
 !34 = !DICompositeType(tag: DW_TAG_structure_type, scope: !2, file: !2, size: 128, elements: !35)