Original message here
https://gcc.gnu.org/pipermail/gcc-patches/2020-October/557406.html
This has non-RISC-V changes, so I need a global reviewer to look at it.
Jim
On Wed, Nov 4, 2020 at 12:10 PM Jim Wilson <j...@sifive.com> wrote:
>
>
> On Wed, Oct 28, 2020 at 4:59 PM Jim Wilson <j...@sifive.com> wrote:
>
>> 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 <j...@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.jos...@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(-)
>>
>> 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");
>> --
>> 2.17.1
>>
>>
