Unverified Commit b1338d1e authored by Thurston Dang's avatar Thurston Dang Committed by GitHub
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[tsan] Shrink RiscV64 48-bit LowApp region slightly to speed up TSan RestoreAddr (#72316) 



The RiscV64 48-bit mappings introduced in
46cb8d9a necessitated changing
RestoreAddr to use 4-bits as the indicator. This roughly halves the
speed of RestoreAddr, because it is now brute-force testing addresses in
1TB increments, rather than 2TB increments. Crucially, this slowdown
applies to TSan on all platforms, not just RiscV64 48-bit.

This patch slightly shrinks the RiscV64 48-bit LowApp region mapping
(from 5TB to 4TB); we hope that 4TB ought to be enough for anybody,
especially since there is no ASLR applied to the binary in this region.
This allows restoring RestoreAddr to use 3-bits as the indicator again,
thus speeding up TSan on all platforms.

Co-authored-by: default avatarThurston Dang <thurston@google.com>
parent 3ce5c04a

compiler-rt/lib/tsan/rtl/tsan_platform.h

+4 −4
Original line number Diff line number Diff line
@@ -413,18 +413,18 @@ struct MappingRiscv64_39 { 


/*

C/C++ on linux/riscv64 (48-bit VMA)

0000 0000 1000 - 0500 0000 0000: main binary                      ( 5 TB)

0000 0000 1000 - 0400 0000 0000: main binary                      ( 4 TB)

0500 0000 0000 - 2000 0000 0000: -

2000 0000 0000 - 4000 0000 0000: shadow memory                    (32 TB)

4000 0000 0000 - 4800 0000 0000: metainfo                         ( 8 TB)

4800 0000 0000 - 5555 5555 5000: -

5555 5555 5000 - 5a00 0000 0000: main binary (PIE)                (~5 TB)

5a00 0000 0000 - 7a00 0000 0000: -

7a00 0000 0000 - 7fff ffff ffff: libraries and main thread stack  ( 5 TB)

7a00 0000 0000 - 7fff ffff ffff: libraries and main thread stack  ( 6 TB)

*/

struct MappingRiscv64_48 {

  static const uptr kLoAppMemBeg = 0x000000001000ull;

  static const uptr kLoAppMemEnd = 0x050000000000ull;

  static const uptr kLoAppMemEnd = 0x040000000000ull;

  static const uptr kShadowBeg = 0x200000000000ull;

  static const uptr kShadowEnd = 0x400000000000ull;

  static const uptr kMetaShadowBeg = 0x400000000000ull;
@@ -967,7 +967,7 @@ struct RestoreAddrImpl { 
        Mapping::kMidAppMemEnd, Mapping::kHiAppMemBeg, Mapping::kHiAppMemEnd,

        Mapping::kHeapMemBeg,   Mapping::kHeapMemEnd,

    };

    const uptr indicator = 0x0f0000000000ull;

    const uptr indicator = 0x0e0000000000ull;

    const uptr ind_lsb = 1ull << LeastSignificantSetBitIndex(indicator);

    for (uptr i = 0; i < ARRAY_SIZE(ranges); i += 2) {

      uptr beg = ranges[i];