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[hwasan] Optimize shadow shapshot size #67068

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Sep 22, 2023
Merged

[hwasan] Optimize shadow shapshot size #67068

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51 changes: 36 additions & 15 deletions compiler-rt/lib/hwasan/hwasan_report.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -323,6 +323,21 @@ static uptr GetGlobalSizeFromDescriptor(uptr ptr) {

void ReportStats() {}

constexpr uptr kDumpWidth = 16;
constexpr uptr kShadowLines = 17;
constexpr uptr kShadowDumpSize = kShadowLines * kDumpWidth;

constexpr uptr kShortLines = 3;
constexpr uptr kShortDumpSize = kShortLines * kDumpWidth;
constexpr uptr kShortDumpOffset = (kShadowLines - kShortLines) / 2 * kDumpWidth;

static uptr GetPrintTagStart(uptr addr) {
addr = MemToShadow(addr);
addr = RoundDownTo(addr, kDumpWidth);
addr -= kDumpWidth * (kShadowLines / 2);
return addr;
}

template <typename PrintTag>
static void PrintTagInfoAroundAddr(uptr addr, uptr num_rows,
InternalScopedString &s,
Expand Down Expand Up @@ -352,7 +367,7 @@ static void PrintTagsAroundAddr(uptr addr, GetTag get_tag,
"Memory tags around the buggy address (one tag corresponds to %zd "
"bytes):\n",
kShadowAlignment);
PrintTagInfoAroundAddr(addr, 17, s,
PrintTagInfoAroundAddr(addr, kShadowLines, s,
[&](InternalScopedString &s, uptr tag_addr) {
tag_t tag = get_tag(tag_addr);
s.AppendF("%02x", tag);
Expand All @@ -362,7 +377,7 @@ static void PrintTagsAroundAddr(uptr addr, GetTag get_tag,
"Tags for short granules around the buggy address (one tag corresponds "
"to %zd bytes):\n",
kShadowAlignment);
PrintTagInfoAroundAddr(addr, 3, s,
PrintTagInfoAroundAddr(addr, kShortLines, s,
[&](InternalScopedString &s, uptr tag_addr) {
tag_t tag = get_tag(tag_addr);
if (tag >= 1 && tag <= kShadowAlignment) {
Expand Down Expand Up @@ -439,8 +454,8 @@ class BaseReport {

struct Shadow {
uptr addr = 0;
tag_t tags[512] = {};
tag_t short_tags[ARRAY_SIZE(tags)] = {};
tag_t tags[kShadowDumpSize] = {};
tag_t short_tags[kShortDumpSize] = {};
};

sptr FindMismatchOffset() const;
Expand Down Expand Up @@ -508,18 +523,24 @@ BaseReport::Shadow BaseReport::CopyShadow() const {
if (!MemIsApp(untagged_addr))
return result;

result.addr = MemToShadow(untagged_addr) - ARRAY_SIZE(result.tags) / 2;
for (uptr i = 0; i < ARRAY_SIZE(result.tags); ++i) {
uptr tag_addr = result.addr + i;
if (!MemIsShadow(tag_addr))
continue;
result.tags[i] = *reinterpret_cast<tag_t *>(tag_addr);
uptr granule_addr = ShadowToMem(tag_addr);
if (1 <= result.tags[i] && result.tags[i] <= kShadowAlignment &&
result.addr = GetPrintTagStart(untagged_addr + mismatch_offset);
uptr tag_addr = result.addr;
for (tag_t &tag_copy : result.tags) {
if (MemIsShadow(tag_addr))
tag_copy = *reinterpret_cast<tag_t *>(tag_addr);
++tag_addr;
}

uptr short_tags_addr = result.addr + kShortDumpOffset;
for (tag_t &tag_copy : result.short_tags) {
tag_t tag = GetTagCopy(short_tags_addr);
uptr granule_addr = ShadowToMem(short_tags_addr);
if (1 <= tag && tag <= kShadowAlignment &&
IsAccessibleMemoryRange(granule_addr, kShadowAlignment)) {
result.short_tags[i] =
tag_copy =
*reinterpret_cast<tag_t *>(granule_addr + kShadowAlignment - 1);
}
++short_tags_addr;
}
return result;
}
Expand All @@ -532,8 +553,8 @@ tag_t BaseReport::GetTagCopy(uptr addr) const {
}

tag_t BaseReport::GetShortTagCopy(uptr addr) const {
CHECK_GE(addr, shadow.addr);
uptr idx = addr - shadow.addr;
CHECK_GE(addr, shadow.addr + kShortDumpOffset);
uptr idx = addr - shadow.addr - kShortDumpOffset;
CHECK_LT(idx, ARRAY_SIZE(shadow.short_tags));
return shadow.short_tags[idx];
}
Expand Down