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回复：[PATCH] Asan changes for RISC-V.

Message ID 647e1cb6-5382-43f9-b8d9-3a44977b67c0.cooper.joshua@linux.alibaba.com
State Deferred, archived
Headers
Series 回复：[PATCH] Asan changes for RISC-V. |

Commit Message

joshua April 20, 2022, 2:19 a.m. UTC 
  Does Asan work for RISC-V currently? It seems that '-fsanitize=address' is still unsupported for RISC-V. If I add '--enable-libsanitizer' in Makefile.in to reconfigure, there are compiling errors.
Is it because # libsanitizer not supported rv32, but it will break the rv64 multi-lib build, so we disable that temporally until rv32 supported# in Makefile.in?
------------------------------------------------------------------
发件人：Jim Wilson <jimw@sifive.com>
发送时间：2020年10月29日(星期四) 07:59
收件人：gcc-patches <gcc-patches@gcc.gnu.org>
抄　送：cooper.joshua <cooper.joshua@linux.alibaba.com>; Jim Wilson <jimw@sifive.com>
主　题：[PATCH] Asan changes for RISC-V.

We have only riscv64 asan support, there is no riscv32 support as yet.  So I
need to be able to conditionally enable asan support for the riscv target.  I
implemented this by returning zero from the asan_shadow_offset function.  This
requires a change to toplev.c and docs in target.def.

The asan support works on a 5.5 kernel, but does not work on a 4.15 kernel.
The problem is that the asan high memory region is a small wedge below
0x4000000000.  The new kernel puts shared libraries at 0x3fffffffff and going
down which works.  But the old kernel puts shared libraries at 0x2000000000
and going up which does not work, as it isn't in any recognized memory
region.  This might be fixable with more asan work, but we don't really need
support for old kernel versions.

The asan port is curious in that it uses 1<<29 for the shadow offset, but all
other 64-bit targets use a number larger than 1<<32.  But what we have is
working OK for now.

I did a make check RUNTESTFLAGS="asan.exp" on Fedora rawhide image running on
qemu and the results look reasonable.

  === gcc Summary ===

# of expected passes  1905
# of unexpected failures 11
# of unsupported tests  224

  === g++ Summary ===

# of expected passes  2002
# of unexpected failures 6
# of unresolved testcases 1
# of unsupported tests  175

OK?

Jim

2020-10-28  Jim Wilson  <jimw@sifive.com>

 gcc/
 * config/riscv/riscv.c (riscv_asan_shadow_offset): New.
 (TARGET_ASAN_SHADOW_OFFSET): New.
 * doc/tm.texi: Regenerated.
 * target.def (asan_shadow_offset); Mention that it can return zero.
 * toplev.c (process_options): Check for and handle zero return from
 targetm.asan_shadow_offset call.

Co-Authored-By: cooper.joshua <cooper.joshua@linux.alibaba.com>
---
 gcc/config/riscv/riscv.c | 16 ++++++++++++++++
 gcc/doc/tm.texi          |  3 ++-
 gcc/target.def           |  3 ++-
 gcc/toplev.c             |  3 ++-
 4 files changed, 22 insertions(+), 3 deletions(-)
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Patch

diff --git a/gcc/config/riscv/riscv.c b/gcc/config/riscv/riscv.c
index 989a9f15250..6909e200de1 100644
--- a/gcc/config/riscv/riscv.c
+++ b/gcc/config/riscv/riscv.c
@@ -5299,6 +5299,19 @@  riscv_gpr_save_operation_p (rtx op)
   return true;
 }

+/* Implement TARGET_ASAN_SHADOW_OFFSET.  */
+
+static unsigned HOST_WIDE_INT
+riscv_asan_shadow_offset (void)
+{
+  /* We only have libsanitizer support for RV64 at present.
+
+     This number must match kRiscv*_ShadowOffset* in the file
+     libsanitizer/asan/asan_mapping.h which is currently 1<<29 for rv64,
+     even though 1<<36 makes more sense.  */
+  return TARGET_64BIT ? (HOST_WIDE_INT_1 << 29) : 0;
+}
+
 /* Initialize the GCC target structure.  */
 #undef TARGET_ASM_ALIGNED_HI_OP
 #define TARGET_ASM_ALIGNED_HI_OP "\t.half\t"
@@ -5482,6 +5495,9 @@  riscv_gpr_save_operation_p (rtx op)
 #undef TARGET_NEW_ADDRESS_PROFITABLE_P
 #define TARGET_NEW_ADDRESS_PROFITABLE_P riscv_new_address_profitable_p

+#undef TARGET_ASAN_SHADOW_OFFSET
+#define TARGET_ASAN_SHADOW_OFFSET riscv_asan_shadow_offset
+
 struct gcc_target targetm = TARGET_INITIALIZER;

 #include "gt-riscv.h"
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 24c37f655c8..39c596b647a 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -12078,7 +12078,8 @@  is zero, which disables this optimization.
 @deftypefn {Target Hook} {unsigned HOST_WIDE_INT} TARGET_ASAN_SHADOW_OFFSET (void)
 Return the offset bitwise ored into shifted address to get corresponding
 Address Sanitizer shadow memory address.  NULL if Address Sanitizer is not
-supported by the target.
+supported by the target.  May return 0 if Address Sanitizer is not supported
+by a subtarget.
 @end deftypefn

 @deftypefn {Target Hook} {unsigned HOST_WIDE_INT} TARGET_MEMMODEL_CHECK (unsigned HOST_WIDE_INT @var{val})
diff --git a/gcc/target.def b/gcc/target.def
index ed2da154e30..268b56b6ebd 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -4452,7 +4452,8 @@  DEFHOOK
 (asan_shadow_offset,
  "Return the offset bitwise ored into shifted address to get corresponding\n\
 Address Sanitizer shadow memory address.  NULL if Address Sanitizer is not\n\
-supported by the target.",
+supported by the target.  May return 0 if Address Sanitizer is not supported\n\
+by a subtarget.",
  unsigned HOST_WIDE_INT, (void),
  NULL)

diff --git a/gcc/toplev.c b/gcc/toplev.c
index 20e231f4d2a..cf89598252c 100644
--- a/gcc/toplev.c
+++ b/gcc/toplev.c
@@ -1834,7 +1834,8 @@  process_options (void)
     }

   if ((flag_sanitize & SANITIZE_USER_ADDRESS)
-      && targetm.asan_shadow_offset == NULL)
+      && ((targetm.asan_shadow_offset == NULL)
+   || (targetm.asan_shadow_offset () == 0)))
     {
       warning_at (UNKNOWN_LOCATION, 0,
     "%<-fsanitize=address%> not supported for this target");