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PSA/eBPF: use slice-by-8 algorithm for CRC-32 #3688

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merged 5 commits into from
Nov 12, 2022
Merged

PSA/eBPF: use slice-by-8 algorithm for CRC-32 #3688

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c6f4636
Add CRC32 slice-by-8 algo
majchwo Oct 21, 2022
f4498e8
Fix cpp lint
majchwo Nov 11, 2022
f3112b4
Merge branch 'main' into majchwo/crc32-sb8-algo
osinstom Nov 12, 2022
0526224
Fix back-edge verifier error
osinstom Nov 12, 2022
273778d
Fix cpplint
osinstom Nov 12, 2022
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99 changes: 97 additions & 2 deletions backends/ebpf/psa/ebpfPsaGen.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -135,8 +135,18 @@ void PSAEbpfGenerator::emitTypes(CodeBuilder *builder) const {
egress->parser->emitTypes(builder);
egress->control->emitTableTypes(builder);
builder->newline();
emitCRC32LookupTableTypes(builder);
builder->newline();
}
void PSAEbpfGenerator::emitCRC32LookupTableTypes(CodeBuilder *builder) const {
builder->append("struct lookup_tbl_val ");
builder->blockStart();
builder->emitIndent();
builder->append("u32 table[2048]");
builder->endOfStatement(true);
builder->blockEnd(true);
builder->endOfStatement(true);
}

void PSAEbpfGenerator::emitGlobalHeadersMetadata(CodeBuilder *builder) const {
builder->append("struct hdr_md ");
builder->blockStart();
Expand Down Expand Up @@ -197,6 +207,7 @@ void PSAEbpfGenerator::emitInitializer(CodeBuilder *builder) const {
ingress->control->emitTableInitializers(builder);
egress->control->emitTableInitializers(builder);
builder->newline();
emitCRC32LookupTableInitializer(builder);
builder->emitIndent();
builder->appendLine("return 0;");
builder->blockEnd(true);
Expand Down Expand Up @@ -404,10 +415,94 @@ void PSAArchTC::emitInstances(CodeBuilder *builder) const {

emitPacketReplicationTables(builder);
emitPipelineInstances(builder);

emitCRC32LookupTableInstance(builder);
builder->appendLine("REGISTER_END()");
builder->newline();
}
void PSAArchTC::emitCRC32LookupTableInstance(CodeBuilder *builder) const {
builder->target->emitTableDecl(builder, cstring("crc_lookup_tbl"), TableArray, "u32",
cstring("struct lookup_tbl_val"), 1);
}
void PSAEbpfGenerator::emitCRC32LookupTableInitializer(CodeBuilder *builder) const {
cstring keyName = "lookup_tbl_key";
cstring valueName = "lookup_tbl_value";
cstring instanceName = "crc_lookup_tbl";

builder->emitIndent();
builder->appendFormat("u32 %s = 0", keyName.c_str());
builder->endOfStatement(true);
builder->emitIndent();
builder->appendFormat("struct lookup_tbl_val* %s = BPF_MAP_LOOKUP_ELEM(%s, &%s)",
valueName.c_str(), instanceName.c_str(), keyName.c_str());
builder->endOfStatement(true);
builder->emitIndent();
builder->appendFormat("if (%s != NULL)", valueName.c_str());
builder->blockStart();
builder->emitIndent();
builder->appendFormat("for (u16 i = 0; i <= 255; i++)");
builder->blockStart();
builder->emitIndent();
builder->appendFormat("u32 crc = i");
builder->endOfStatement(true);
builder->emitIndent();
builder->appendFormat("for (u16 j = 0; j < 8; j++)");
builder->blockStart();
builder->emitIndent();
builder->appendFormat("crc = (crc >> 1) ^ ((crc & 1) * 3988292384)");
builder->endOfStatement(true);
builder->blockEnd(true);
builder->emitIndent();
builder->appendFormat("%s->table[i] = crc", valueName.c_str());
builder->endOfStatement(true);
builder->blockEnd(true);
builder->emitIndent();
builder->appendFormat("for (u16 i = 0; i <= 255; i++)");
builder->blockStart();
builder->emitIndent();
builder->appendFormat("%s->table[256+i] = "
"(%s->table[0+i] >> 8) ^ %s->table[(%s->table[0+i] & 0xFF)]",
valueName.c_str(), valueName.c_str(), valueName.c_str(),
valueName.c_str());
builder->endOfStatement(true);
builder->emitIndent();
builder->appendFormat("%s->table[512+i] = "
"(%s->table[256+i] >> 8) ^ %s->table[(%s->table[256+i] & 0xFF)]",
valueName.c_str(), valueName.c_str(), valueName.c_str(),
valueName.c_str());
builder->endOfStatement(true);
builder->emitIndent();
builder->appendFormat("%s->table[768+i] = "
"(%s->table[512+i] >> 8) ^ %s->table[(%s->table[512+i] & 0xFF)]",
valueName.c_str(), valueName.c_str(), valueName.c_str(),
valueName.c_str());
builder->endOfStatement(true);
builder->emitIndent();
builder->appendFormat("%s->table[1024+i] = "
"(%s->table[768+i] >> 8) ^ %s->table[(%s->table[768+i] & 0xFF)]",
valueName.c_str(), valueName.c_str(), valueName.c_str(),
valueName.c_str());
builder->endOfStatement(true);
builder->emitIndent();
builder->appendFormat("%s->table[1280+i] = "
"(%s->table[1024+i] >> 8) ^ %s->table[(%s->table[1024+i] & 0xFF)]",
valueName.c_str(), valueName.c_str(), valueName.c_str(),
valueName.c_str());
builder->endOfStatement(true);
builder->emitIndent();
builder->appendFormat("%s->table[1536+i] = "
"(%s->table[1280+i] >> 8) ^ %s->table[(%s->table[1280+i] & 0xFF)]",
valueName.c_str(), valueName.c_str(), valueName.c_str(),
valueName.c_str());
builder->endOfStatement(true);
builder->emitIndent();
builder->appendFormat("%s->table[1792+i] = "
"(%s->table[1536+i] >> 8) ^ %s->table[(%s->table[1536+i] & 0xFF)]",
valueName.c_str(), valueName.c_str(), valueName.c_str(),
valueName.c_str());
builder->endOfStatement(true);
builder->blockEnd(true);
builder->blockEnd(true);
}

void PSAArchTC::emitInitializerSection(CodeBuilder *builder) const {
builder->appendLine("SEC(\"classifier/map-initializer\")");
Expand Down
4 changes: 4 additions & 0 deletions backends/ebpf/psa/ebpfPsaGen.h
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Original file line number Diff line number Diff line change
Expand Up @@ -62,6 +62,8 @@ class PSAEbpfGenerator {
void emitInitializer(CodeBuilder *builder) const;
virtual void emitInitializerSection(CodeBuilder *builder) const = 0;
void emitHelperFunctions(CodeBuilder *builder) const;
void emitCRC32LookupTableTypes(CodeBuilder *builder) const;
void emitCRC32LookupTableInitializer(CodeBuilder *builder) const;
};

class PSAArchTC : public PSAEbpfGenerator {
Expand All @@ -76,6 +78,8 @@ class PSAArchTC : public PSAEbpfGenerator {

void emitInstances(CodeBuilder *builder) const override;
void emitInitializerSection(CodeBuilder *builder) const override;
void emitCRC32LookupTableInstance(CodeBuilder *builder) const;

};

class ConvertToEbpfPSA : public Transform {
Expand Down
100 changes: 83 additions & 17 deletions backends/ebpf/psa/externs/ebpfPsaHashAlgorithm.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -51,24 +51,90 @@ void EBPFHashAlgorithmPSA::emitAddData(CodeBuilder *builder, int dataPos,

void CRCChecksumAlgorithm::emitUpdateMethod(CodeBuilder* builder, int crcWidth) {
// Note that this update method is optimized for our CRC16 and CRC32, custom
// version may require other method of update. To deal with byte order, data
// version may require other method of update. To deal with byte order data
// is read from the end of buffer.
cstring code = "static __always_inline\n"
"void crc%w%_update(u%w% * reg, const u8 * data, "
"u16 data_size, const u%w% poly) {\n"
" data += data_size - 1;\n"
" #pragma clang loop unroll(full)\n"
" for (u16 i = 0; i < data_size; i++) {\n"
" bpf_trace_message(\"CRC%w%: data byte: %x\\n\", *data);\n"
" *reg ^= *data;\n"
" for (u8 bit = 0; bit < 8; bit++) {\n"
" *reg = (*reg) & 1 ? ((*reg) >> 1) ^ poly : (*reg) >> 1;\n"
" }\n"
" data--;\n"
" }\n"
"}";
code = code.replace("%w%", Util::printf_format("%d", crcWidth));
builder->appendLine(code);
if (crcWidth == 16){
cstring code = "static __always_inline\n"
"void crc%w%_update(u%w% * reg, const u8 * data, u16 data_size, const u%w% poly) {\n"
" data += data_size - 1;\n"
" for (u16 i = 0; i < data_size; i++) {\n"
" bpf_trace_message(\"CRC%w%: data byte: %x\\n\", *data);\n"
" *reg ^= *data;\n"
" for (u8 bit = 0; bit < 8; bit++) {\n"
" *reg = (*reg) & 1 ? ((*reg) >> 1) ^ poly : (*reg) >> 1;\n"
" }\n"
" data--;\n"
" }\n"
"}";
code = code.replace("%w%", Util::printf_format("%d", crcWidth));
builder->appendLine(code);
} else if (crcWidth == 32) {


cstring code = "static __always_inline\n"
"void crc%w%_update(u%w% * reg, const u8 * data, u16 data_size, "
"const u%w% poly) {\n"
" data += data_size - 4;\n"
" u32* current = (u32*) data;\n"
" struct lookup_tbl_val* lookup_table;\n"
" u32 index = 0;\n"
" lookup_table = BPF_MAP_LOOKUP_ELEM(crc_lookup_tbl, &index);\n"
" u32 lookup_key = 0;\n"
" u32 lookup_value = 0;\n"
" u32 lookup_value1 = 0;\n"
" u32 lookup_value2 = 0;\n"
" u32 lookup_value3 = 0;\n"
" u32 lookup_value4 = 0;\n"
" u32 lookup_value5 = 0;\n"
" u32 lookup_value6 = 0;\n"
" u32 lookup_value7 = 0;\n"
" u32 lookup_value8 = 0;\n"
" u16 tmp = 0;\n"
" if (lookup_table != NULL) {\n"
" for (u16 i = data_size; i >= 8; i -= 8) {\n"
" bpf_trace_message(\"CRC32: data byte: %x\", *current);\n"
" u32 one = __builtin_bswap32(*current--) ^ *reg;\n"
" bpf_trace_message(\"CRC32: data byte: %x\", *current);\n"
" u32 two = __builtin_bswap32(*current--);\n"
" lookup_key = (one & 0x000000FF);\n"
" lookup_value8 = lookup_table->table[(u16)(1792 + (u8)lookup_key)];\n"
" lookup_key = (one >> 8) & 0x000000FF;\n"
" lookup_value7 = lookup_table->table[(u16)(1536 + (u8)lookup_key)];\n"
" lookup_key = (one >> 16) & 0x000000FF;\n"
" lookup_value6 = lookup_table->table[(u16)(1280 + (u8)lookup_key)];\n"
" lookup_key = one >> 24;\n"
" lookup_value5 = "
"lookup_table->table[(u16)(1024 + (u8)(lookup_key))];\n"
" lookup_key = (two & 0x000000FF);\n"
" lookup_value4 = lookup_table->table[(u16)(768 + (u8)lookup_key)];\n"
" lookup_key = (two >> 8) & 0x000000FF;\n"
" lookup_value3 = lookup_table->table[(u16)(512 + (u8)lookup_key)];\n"
" lookup_key = (two >> 16) & 0x000000FF;\n"
" lookup_value2 = lookup_table->table[(u16)(256 + (u8)lookup_key)];\n"
" lookup_key = two >> 24;\n"
" lookup_value1 = lookup_table->table[(u8)(lookup_key)];\n"
" *reg = lookup_value8 ^ lookup_value7 ^ lookup_value6 ^ lookup_value5"
" ^ lookup_value4 ^\n"
" lookup_value3 ^ lookup_value2 ^ lookup_value1;\n"
" tmp += 8;\n"
" }\n"
" unsigned char *currentChar = (unsigned char *) current;\n"
" currentChar+= 3;\n"
" volatile int std_algo_lookup_key = 0;\n"
" for (u16 i = tmp; i < data_size; i++) {\n"
" bpf_trace_message(\"CRC32: data byte: %x\\n\", *current);\n"
" std_algo_lookup_key = (u32)(((*reg) & 0xFF) ^ *currentChar--);\n"
" if (std_algo_lookup_key >= 0) {\n"
" lookup_value = "
"lookup_table->table[(u8)(std_algo_lookup_key & 255)];\n"
" }\n"
" *reg = ((*reg) >> 8) ^ lookup_value;\n"
" }\n"
" }\n"
"}";
code = code.replace("%w%", Util::printf_format("%d", crcWidth));
builder->appendLine(code);
}
}

void CRCChecksumAlgorithm::emitVariables(CodeBuilder* builder,
Expand Down