Hash :
150f1242
Author :
Date :
2025-03-11T18:34:37
Metal: Provoking vertex conv. reads out of buffer The provoking vertex helper would encode the addresses of index count and primitive count variables, not their values. This would cause the provoking vertex conversion shader to read overly many indices. Not testable easily from the API, as the excessive read is hard to test. Would cause context loss on the existing tests when run with validation. Bug: angleproject:419755715 Change-Id: Id81ecc66513c0eac1e95d11937f12d9bebb5e11e Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6578202 Auto-Submit: Kimmo Kinnunen <kkinnunen@apple.com> Commit-Queue: Kimmo Kinnunen <kkinnunen@apple.com> Commit-Queue: Geoff Lang <geofflang@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>
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//
// Copyright 2021 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// ProvokingVertexHelper.mm:
// Implements the class methods for ProvokingVertexHelper.
//
#include "libANGLE/renderer/metal/ProvokingVertexHelper.h"
#import <Foundation/Foundation.h>
#include "libANGLE/Display.h"
#include "libANGLE/renderer/metal/ContextMtl.h"
#include "libANGLE/renderer/metal/DisplayMtl.h"
#include "libANGLE/renderer/metal/mtl_common.h"
#include "libANGLE/renderer/metal/shaders/rewrite_indices_shared.h"
namespace rx
{
namespace
{
constexpr size_t kInitialIndexBufferSize = 0xFFFF; // Initial 64k pool.
}
static inline uint primCountForIndexCount(const uint fixIndexBufferKey, const uint indexCount)
{
const uint fixIndexBufferMode =
(fixIndexBufferKey >> MtlFixIndexBufferKeyModeShift) & MtlFixIndexBufferKeyModeMask;
switch (fixIndexBufferMode)
{
case MtlFixIndexBufferKeyPoints:
return indexCount;
case MtlFixIndexBufferKeyLines:
return indexCount / 2;
case MtlFixIndexBufferKeyLineStrip:
return (uint)MAX(0, (int)indexCount - 1);
case MtlFixIndexBufferKeyLineLoop:
return (uint)MAX(0, (int)indexCount);
case MtlFixIndexBufferKeyTriangles:
return indexCount / 3;
case MtlFixIndexBufferKeyTriangleStrip:
return (uint)MAX(0, (int)indexCount - 2);
case MtlFixIndexBufferKeyTriangleFan:
return (uint)MAX(0, (int)indexCount - 2);
default:
ASSERT(false);
return 0;
}
}
static inline uint indexCountForPrimCount(const uint fixIndexBufferKey, const uint primCount)
{
const uint fixIndexBufferMode =
(fixIndexBufferKey >> MtlFixIndexBufferKeyModeShift) & MtlFixIndexBufferKeyModeMask;
switch (fixIndexBufferMode)
{
case MtlFixIndexBufferKeyPoints:
return primCount;
case MtlFixIndexBufferKeyLines:
return primCount * 2;
case MtlFixIndexBufferKeyLineStrip:
return primCount * 2;
case MtlFixIndexBufferKeyLineLoop:
return primCount * 2;
case MtlFixIndexBufferKeyTriangles:
return primCount * 3;
case MtlFixIndexBufferKeyTriangleStrip:
return primCount * 3;
case MtlFixIndexBufferKeyTriangleFan:
return primCount * 3;
default:
ASSERT(false);
return 0;
}
}
static inline gl::PrimitiveMode getNewPrimitiveMode(const uint fixIndexBufferKey)
{
const uint fixIndexBufferMode =
(fixIndexBufferKey >> MtlFixIndexBufferKeyModeShift) & MtlFixIndexBufferKeyModeMask;
switch (fixIndexBufferMode)
{
case MtlFixIndexBufferKeyPoints:
return gl::PrimitiveMode::Points;
case MtlFixIndexBufferKeyLines:
return gl::PrimitiveMode::Lines;
case MtlFixIndexBufferKeyLineStrip:
return gl::PrimitiveMode::Lines;
case MtlFixIndexBufferKeyLineLoop:
return gl::PrimitiveMode::Lines;
case MtlFixIndexBufferKeyTriangles:
return gl::PrimitiveMode::Triangles;
case MtlFixIndexBufferKeyTriangleStrip:
return gl::PrimitiveMode::Triangles;
case MtlFixIndexBufferKeyTriangleFan:
return gl::PrimitiveMode::Triangles;
default:
ASSERT(false);
return gl::PrimitiveMode::InvalidEnum;
}
}
ProvokingVertexHelper::ProvokingVertexHelper(ContextMtl *context) : mIndexBuffers(false)
{
mIndexBuffers.initialize(context, kInitialIndexBufferSize, mtl::kIndexBufferOffsetAlignment, 0);
}
void ProvokingVertexHelper::onDestroy(ContextMtl *context)
{
mIndexBuffers.destroy(context);
}
void ProvokingVertexHelper::releaseInFlightBuffers(ContextMtl *contextMtl)
{
mIndexBuffers.releaseInFlightBuffers(contextMtl);
}
static uint buildIndexBufferKey(const mtl::ProvokingVertexComputePipelineDesc &pipelineDesc)
{
uint indexBufferKey = 0;
gl::DrawElementsType elementType = (gl::DrawElementsType)pipelineDesc.elementType;
bool doPrimPrestart = pipelineDesc.primitiveRestartEnabled;
gl::PrimitiveMode primMode = pipelineDesc.primitiveMode;
switch (elementType)
{
case gl::DrawElementsType::UnsignedShort:
indexBufferKey |= MtlFixIndexBufferKeyUint16 << MtlFixIndexBufferKeyInShift;
indexBufferKey |= MtlFixIndexBufferKeyUint16 << MtlFixIndexBufferKeyOutShift;
break;
case gl::DrawElementsType::UnsignedInt:
indexBufferKey |= MtlFixIndexBufferKeyUint32 << MtlFixIndexBufferKeyInShift;
indexBufferKey |= MtlFixIndexBufferKeyUint32 << MtlFixIndexBufferKeyOutShift;
break;
default:
ASSERT(false); // Index type should only be short or int.
break;
}
indexBufferKey |= (uint)primMode << MtlFixIndexBufferKeyModeShift;
indexBufferKey |= doPrimPrestart ? MtlFixIndexBufferKeyPrimRestart : 0;
// We only rewrite indices if we're switching the provoking vertex mode.
indexBufferKey |= MtlFixIndexBufferKeyProvokingVertexLast;
return indexBufferKey;
}
angle::Result ProvokingVertexHelper::getComputePipleineState(
ContextMtl *context,
const mtl::ProvokingVertexComputePipelineDesc &desc,
angle::ObjCPtr<id<MTLComputePipelineState>> *outComputePipeline)
{
auto iter = mComputeFunctions.find(desc);
if (iter != mComputeFunctions.end())
{
return context->getPipelineCache().getComputePipeline(context, iter->second,
outComputePipeline);
}
id<MTLLibrary> provokingVertexLibrary = context->getDisplay()->getDefaultShadersLib();
uint indexBufferKey = buildIndexBufferKey(desc);
auto fcValues = angle::adoptObjCPtr([[MTLFunctionConstantValues alloc] init]);
[fcValues setConstantValue:&indexBufferKey type:MTLDataTypeUInt withName:@"fixIndexBufferKey"];
angle::ObjCPtr<id<MTLFunction>> computeShader;
if (desc.generateIndices)
{
ANGLE_TRY(CreateMslShader(context, provokingVertexLibrary, @"genIndexBuffer",
fcValues.get(), &computeShader));
}
else
{
ANGLE_TRY(CreateMslShader(context, provokingVertexLibrary, @"fixIndexBuffer",
fcValues.get(), &computeShader));
}
mComputeFunctions[desc] = computeShader;
return context->getPipelineCache().getComputePipeline(context, computeShader,
outComputePipeline);
}
angle::Result ProvokingVertexHelper::prepareCommandEncoderForDescriptor(
ContextMtl *context,
mtl::ComputeCommandEncoder *encoder,
mtl::ProvokingVertexComputePipelineDesc desc)
{
angle::ObjCPtr<id<MTLComputePipelineState>> pipelineState;
ANGLE_TRY(getComputePipleineState(context, desc, &pipelineState));
encoder->setComputePipelineState(pipelineState);
return angle::Result::Continue;
}
angle::Result ProvokingVertexHelper::preconditionIndexBuffer(ContextMtl *context,
mtl::BufferRef indexBuffer,
size_t indexCount,
size_t indexOffset,
bool primitiveRestartEnabled,
gl::PrimitiveMode primitiveMode,
gl::DrawElementsType elementsType,
size_t &outIndexCount,
size_t &outIndexOffset,
gl::PrimitiveMode &outPrimitiveMode,
mtl::BufferRef &outNewBuffer)
{
// Get specialized program
// Upload index buffer
// dispatch per-primitive?
mtl::ProvokingVertexComputePipelineDesc pipelineDesc;
pipelineDesc.elementType = (uint8_t)elementsType;
pipelineDesc.primitiveMode = primitiveMode;
pipelineDesc.primitiveRestartEnabled = primitiveRestartEnabled;
pipelineDesc.generateIndices = false;
uint indexBufferKey = buildIndexBufferKey(pipelineDesc);
uint primCount = primCountForIndexCount(indexBufferKey, (uint32_t)indexCount);
uint newIndexCount = indexCountForPrimCount(indexBufferKey, primCount);
size_t indexSize = gl::GetDrawElementsTypeSize(elementsType);
size_t newOffset = 0;
mtl::BufferRef newBuffer;
ANGLE_TRY(mIndexBuffers.allocate(context, newIndexCount * indexSize + indexOffset, nullptr,
&newBuffer, &newOffset));
auto threadsPerThreadgroup = MTLSizeMake(MIN(primCount, 64u), 1, 1);
mtl::ComputeCommandEncoder *encoder =
context->getComputeCommandEncoderWithoutEndingRenderEncoder();
ANGLE_TRY(prepareCommandEncoderForDescriptor(context, encoder, pipelineDesc));
encoder->setBuffer(indexBuffer, static_cast<uint32_t>(indexOffset), 0);
encoder->setBufferForWrite(
newBuffer, static_cast<uint32_t>(indexOffset) + static_cast<uint32_t>(newOffset), 1);
encoder->setData(static_cast<uint>(indexCount), 2);
encoder->setData(primCount, 3);
encoder->dispatch(
MTLSizeMake((primCount + threadsPerThreadgroup.width - 1) / threadsPerThreadgroup.width, 1,
1),
threadsPerThreadgroup);
outIndexCount = newIndexCount;
outIndexOffset = newOffset;
outPrimitiveMode = getNewPrimitiveMode(indexBufferKey);
outNewBuffer = newBuffer;
return angle::Result::Continue;
}
angle::Result ProvokingVertexHelper::generateIndexBuffer(ContextMtl *context,
size_t first,
size_t indexCount,
gl::PrimitiveMode primitiveMode,
gl::DrawElementsType elementsType,
size_t &outIndexCount,
size_t &outIndexOffset,
gl::PrimitiveMode &outPrimitiveMode,
mtl::BufferRef &outNewBuffer)
{
// Get specialized program
// Upload index buffer
// dispatch per-primitive?
mtl::ProvokingVertexComputePipelineDesc pipelineDesc;
pipelineDesc.elementType = (uint8_t)elementsType;
pipelineDesc.primitiveMode = primitiveMode;
pipelineDesc.primitiveRestartEnabled = false;
pipelineDesc.generateIndices = true;
uint indexBufferKey = buildIndexBufferKey(pipelineDesc);
uint primCount = primCountForIndexCount(indexBufferKey, (uint32_t)indexCount);
uint newIndexCount = indexCountForPrimCount(indexBufferKey, primCount);
size_t indexSize = gl::GetDrawElementsTypeSize(elementsType);
size_t newIndexOffset = 0;
mtl::BufferRef newBuffer;
ANGLE_TRY(mIndexBuffers.allocate(context, newIndexCount * indexSize, nullptr, &newBuffer,
&newIndexOffset));
auto threadsPerThreadgroup = MTLSizeMake(MIN(primCount, 64u), 1, 1);
mtl::ComputeCommandEncoder *encoder =
context->getComputeCommandEncoderWithoutEndingRenderEncoder();
ANGLE_TRY(prepareCommandEncoderForDescriptor(context, encoder, pipelineDesc));
encoder->setBufferForWrite(newBuffer, static_cast<uint>(newIndexOffset), 1);
encoder->setData(static_cast<uint>(indexCount), 2);
encoder->setData(primCount, 3);
encoder->setData(static_cast<uint>(first), 4);
encoder->dispatch(
MTLSizeMake((primCount + threadsPerThreadgroup.width - 1) / threadsPerThreadgroup.width, 1,
1),
threadsPerThreadgroup);
outIndexCount = newIndexCount;
outIndexOffset = newIndexOffset;
outPrimitiveMode = getNewPrimitiveMode(indexBufferKey);
outNewBuffer = newBuffer;
return angle::Result::Continue;
}
} // namespace rx