On 2024-12-01 11:35 p.m., [email protected] wrote:
From: Deepthi Hemraj<[email protected]>

RISC-V offers several virtual memory address schemes (Sv39, Sv48, and Sv57),
but ASan currently supports only Sv39 on RISC-V64.
For RISC-V64 Sv39, ASan uses custom allocator configurations
tuned to manage large allocations efficiently.
These tunings are incompatible with larger address spaces like
Sv48/Sv57 due to differences in region sizes and alignment.

For riscv64, Asan's tuning for Sv39 can be enabled in qemu
by using the appropriate flag in the command line as shown below:
runqemu nographic qemuparams="-cpu rv64,sv39=true"

Additionally, the COMPATIBLE_HOST list in gcc-sanitizers has been
updated to include riscv64. All necessary tests were successfully
conducted on both hardware(Microchip PolarFire SoC)
and the qemurisv64 environment, with ASan effectively
detecting memory errors in both scenarios.


Hi Deepthi,


Nice! Thanks for confirming that the qemu command line option allows gcc-sanitizers to

work without any code changes.


One concern is testing: testers would have know that this flag was needed for gcc-sanitizers.

You could add a comment or documentation note as a hint but that doesn't automate and is error prone for people.

I did note that "spacemonkeydelivers" (!) maintains that :

"Indeed ASAN was ported to RISC-V when Sv39 was the default addressing mode, and changes to run it in Sv48/Sv57 must be made. The issue is related to the way how the address space is split between stack, heap and shadow versions of them."
https://github.com/google/sanitizers/issues/1707#issuecomment-1852404560

so I don't think we've gotten to the best possible general purpose fix but rather a (helpful) work-around.

I don't think we should merge this since there's more work to do for a proper fix.

../Randy




Signed-off-by: Deepthi Hemraj<[email protected]>
---
  meta/recipes-devtools/gcc/gcc-sanitizers.inc | 3 ++-
  1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/meta/recipes-devtools/gcc/gcc-sanitizers.inc 
b/meta/recipes-devtools/gcc/gcc-sanitizers.inc
index 524ebd4ba4..8c98e9cf8a 100644
--- a/meta/recipes-devtools/gcc/gcc-sanitizers.inc
+++ b/meta/recipes-devtools/gcc/gcc-sanitizers.inc
@@ -73,13 +73,14 @@ RRECOMMENDS:${PN}:append:x86 = " liblsan"
  RRECOMMENDS:${PN}:append:x86-64 = " liblsan libtsan"
  RRECOMMENDS:${PN}:append:powerpc64 = " liblsan libtsan"
  RRECOMMENDS:${PN}:append:aarch64 = " liblsan libtsan"
+RRECOMMENDS:${PN}:append:riscv64 = " liblsan libtsan"
do_package_write_ipk[depends] += "virtual/${MLPREFIX}${TARGET_PREFIX}compilerlibs:do_packagedata"
  do_package_write_deb[depends] += 
"virtual/${MLPREFIX}${TARGET_PREFIX}compilerlibs:do_packagedata"
  do_package_write_rpm[depends] += 
"virtual/${MLPREFIX}${TARGET_PREFIX}compilerlibs:do_packagedata"
# Only x86, powerpc, sparc, s390, arm, aarch64 and loongarch64 are supported
-COMPATIBLE_HOST = 
'(x86_64|i.86|powerpc|sparc|s390|arm|aarch64|loongarch64).*-linux'
+COMPATIBLE_HOST = 
'(x86_64|i.86|powerpc|sparc|s390|arm|aarch64|loongarch64|riscv64).*-linux'
  # musl is currently broken entirely
  COMPATIBLE_HOST:libc-musl = 'null'


--
# Randy MacLeod
# Wind River Linux
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