[Buildroot] [PATCHv2 1/2] arch/Config.in.riscv: enable Zicsr and Zifencei standalone extensions with gcc >= 12

[Buildroot] [PATCHv2 1/2] arch/Config.in.riscv: enable Zicsr and Zifencei standalone extensions with gcc >= 12

[Romain Naour]

From: Romain Naour <romain.naour@gmail.com>

Since gcc 12, default Riscv ISA spec version was bump to 20191213 [1].

This introduce a major incompatibility issue is the csr read/write
(csrr*/csrw*) instructions and fence.i instruction has separated from
the "I" extension, become two standalone extensions: Zicsr and
Zifencei; so you might get error messages like that: unrecognized
opcode "csrr" (or "fence.i").

Indeed, without Zifencei we can't build opensbi bootloader [2]:

opensbi-1.0/lib/sbi/sbi_tlb.c: Assembler messages:
opensbi-1.0/lib/sbi/sbi_tlb.c:190: Error: unrecognized opcode `fence.i', extension `zifencei' required

As a workaround, opensbi build system has been patched [3] to use
-march=rv64imafdc_zicsr_zifencei when needed.
This workaround doesn't work in Buildroot due to the local patch
0001-Makefile-Don-t-specify-mabi-or-march.patch removing -march
from CFLAGS.

In the context of Buildroot, we can enable unconditionnaly Zicsr
and Zifencei standalone extensions for gcc >=12 (as recommanded
by [4]) since there will likely no RISC-V cores running Linux that
support the base I instruction, but not the csr and fence extensions...
as even OpenSBI assumes the RISC-V core supports them! [5]

[1] https://gcc.gnu.org/gcc-12/changes.html
[2] https://github.com/riscv-software-src/opensbi/blob/v0.9/lib/sbi/sbi_tlb.c#L173
[3] https://github.com/riscv-software-src/opensbi/commit/5d53b55aa77ffeefd4012445dfa6ad3535e1ff2c
[4] https://groups.google.com/a/groups.riscv.org/g/sw-dev/c/aE1ZeHHCYf4
[5] http://lists.busybox.net/pipermail/buildroot/2022-July/646698.html

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Cc: Mark Corbin <mark@dibsco.co.uk>
---
v2: remove Kconfig symbols BR2_RISCV_ISA_RVZicsr and BR2_RISCV_ISA_RVZifencei
    rework the commit log.
---
 arch/arch.mk.riscv | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arch.mk.riscv b/arch/arch.mk.riscv
index f3bf2b3467..006df7de52 100644
--- a/arch/arch.mk.riscv
+++ b/arch/arch.mk.riscv
@@ -26,5 +26,8 @@ endif
 ifeq ($(BR2_RISCV_ISA_RVC),y)
 GCC_TARGET_ARCH := $(GCC_TARGET_ARCH)c
 endif
+ifeq ($(BR2_TOOLCHAIN_GCC_AT_LEAST_12),y)
+GCC_TARGET_ARCH := $(GCC_TARGET_ARCH)_zicsr_zifencei
+endif
 
 endif
-- 
2.34.3

_______________________________________________
buildroot mailing list
buildroot@buildroot.org
https://lists.buildroot.org/mailman/listinfo/buildroot

[Buildroot] [PATCHv2 2/2] package/gcc: disable libsanitizer for mips64{el} w/ n32 ABI

[Romain Naour]

From: Romain Naour <romain.naour@gmail.com>

libsanitizer has been enabled for mips64{el} in gcc 12 [1] but it
fail to build when n32 ABI is used:

In file included from output/mips64el-buildroot-linux-gnu/sysroot/usr/include/bits/stat.h:25,
                 from output/mips64el-buildroot-linux-gnu/sysroot/usr/include/fcntl.h:78,
                 from ../../../../libsanitizer/sanitizer_common/sanitizer_linux.cpp:55:
output/mips64el-buildroot-linux-gnu/sysroot/usr/include/bits/struct_stat.h:190:8: error: redefinition of ‘struct stat64’
  190 | struct stat64
      |        ^~~~~~

In file included from ../../../../libsanitizer/sanitizer_common/sanitizer_linux.cpp:49:
output/mips64el-buildroot-linux-gnu/sysroot/usr/include/asm/stat.h:52:8: note: previous definition of ‘struct stat64’
   52 | struct stat64 {
      |        ^~~~~~

Disable libsanitizer for mips64 with n32 ABI.

Note: Only glibc toolchains are affected since libsanitizer is
disabled for musl and uClibc-ng toolchains [2].

Fixes:
https://gitlab.com/kubu93/toolchains-builder/-/jobs/2510178651

[1] https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=344e6f9f2abcff9b2bb4b26b693be4a599272f43
[2] https://git.buildroot.net/buildroot/commit/?id=5f4d658d888b539de9a6247ae5b1a0999de5d4ec

Signed-off-by: Romain Naour <romain.naour@gmail.com>
---
v2: fix "if" clauses:
    http://lists.busybox.net/pipermail/buildroot/2022-July/646700.html
---
 package/gcc/gcc.mk | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/package/gcc/gcc.mk b/package/gcc/gcc.mk
index 128cf8421d..2892f456cc 100644
--- a/package/gcc/gcc.mk
+++ b/package/gcc/gcc.mk
@@ -135,6 +135,13 @@ ifeq ($(BR2_sparc)$(BR2_sparc64),y)
 HOST_GCC_COMMON_CONF_OPTS += --disable-libsanitizer
 endif
 
+# libsanitizer is available for mips64{el} since gcc 12 but fail to build
+# with n32 ABI due to struct stat64 definition clash due to mixing
+# kernel and user headers.
+ifeq ($(BR2_mips64)$(BR2_mips64el):$(BR2_MIPS_NABI32),y:y)
+HOST_GCC_COMMON_CONF_OPTS += --disable-libsanitizer
+endif
+
 # The logic in libbacktrace/configure.ac to detect if __sync builtins
 # are available assumes they are as soon as target_subdir is not
 # empty, i.e when cross-compiling. However, some platforms do not have
-- 
2.34.3

_______________________________________________
buildroot mailing list
buildroot@buildroot.org
https://lists.buildroot.org/mailman/listinfo/buildroot