From 654223c799910837c80d0964a971fbdf7808864a Mon Sep 17 00:00:00 2001 From: Thiago Jung Bauermann Date: Tue, 17 Mar 2026 02:24:48 -0700 Subject: [PATCH] GDB: aarch64-linux: Fix build failure on musl systems (cherry picked from commit 02090062127d59978ccc312dabf63c6ea838cd85) When building against musl (e.g. on Alpine Linux), the following error happens: CXX linux-aarch64-low.o In file included from /home/bauermann/src/binutils-gdb/gdbserver/linux-aarch64-low.cc:42: /home/bauermann/src/binutils-gdb/gdbserver/../gdb/arch/aarch64-gcs-linux.h:35:8: error: redefinition of 'struct user_gcs' 35 | struct user_gcs | ^~~~~~~~ In file included from /home/bauermann/src/binutils-gdb/gdbserver/linux-aarch64-low.cc:35: /usr/include/asm/ptrace.h:329:8: note: previous definition of 'struct user_gcs' 329 | struct user_gcs { | ^~~~~~~~ make[2]: *** [Makefile:565: linux-aarch64-low.o] Error 1 aarch64-linux-tdep.c fails to build in the same way. This happens because aarch64-gcs-linux.h uses GCS_MAGIC to see whether the system headers have GCS-related definitions. The problem is that GCS_MAGIC is defined in while struct gcs_user is defined in . It's fine on glibc systems because in the set of system headers that linux-aarch64-low.cc and aarch64-linux-tdep.c include, ends up being included implicitly as well. This doesn't happen when using musl's headers though. There isn't a macro in whose presence is correlated with the presence of the struct user_gcs definition, so a configure check is needed to detect it and conditionally define the struct. Also, this change requires aarch64-linux-tdep.c to stop using struct user_gcs because target-dependent code can't include and thus even if HAVE_STRUCT_USER_GCS is set, the file won't have the struct definition available. To fix this problem, also backport the definition of AARCH64_LINUX_SIZEOF_GCS_REGSET and use it there. Note that there's another build issue with musl, described in PR gdb/33747 affecting compilation of gdb/ser-unix.c. In order to be able to test this patch, I applied the patch in comment 11 there. Tested with a native build on an Alpine Linux aarch64 system, and also verified that all gdb.arch/aarch64-gcs*.exp tests pass on it. Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=33926 Upstream-Status: Submitted [https://sourceware.org/pipermail/gdb-patches/2026-March/226049.html] Co-authored-by: Chris Packham Signed-off-by: Sunil Dora --- gdb/aarch64-linux-tdep.c | 5 +++-- gdb/arch/aarch64-gcs-linux.h | 8 +++++--- gdbsupport/config.in | 3 +++ gdbsupport/configure | 36 ++++++++++++++++++++++++++++++++++++ gdbsupport/configure.ac | 19 +++++++++++++++++++ 5 files changed, 66 insertions(+), 5 deletions(-) diff --git a/gdb/aarch64-linux-tdep.c b/gdb/aarch64-linux-tdep.c index 76bde85188b..6c402e7ecdd 100644 --- a/gdb/aarch64-linux-tdep.c +++ b/gdb/aarch64-linux-tdep.c @@ -1684,8 +1684,9 @@ aarch64_linux_iterate_over_regset_sections (struct gdbarch *gdbarch, gcs_regmap, regcache_supply_regset, regcache_collect_regset }; - cb (".reg-aarch-gcs", sizeof (user_gcs), sizeof (user_gcs), - &aarch64_linux_gcs_regset, "GCS registers", cb_data); + cb (".reg-aarch-gcs", AARCH64_LINUX_SIZEOF_GCS_REGSET, + AARCH64_LINUX_SIZEOF_GCS_REGSET, &aarch64_linux_gcs_regset, + "GCS registers", cb_data); } } diff --git a/gdb/arch/aarch64-gcs-linux.h b/gdb/arch/aarch64-gcs-linux.h index 018ca37a522..632823a8120 100644 --- a/gdb/arch/aarch64-gcs-linux.h +++ b/gdb/arch/aarch64-gcs-linux.h @@ -27,8 +27,7 @@ #define HWCAP_GCS (1ULL << 32) #endif -/* Make sure we only define these if the kernel header doesn't. */ -#ifndef GCS_MAGIC +#ifndef HAVE_STRUCT_USER_GCS /* GCS state (NT_ARM_GCS). */ @@ -39,6 +38,9 @@ struct user_gcs uint64_t gcspr_el0; }; -#endif /* GCS_MAGIC */ +#endif /* HAVE_STRUCT_USER_GCS */ + +/* The GCS regset consists of 3 64-bit registers. */ +#define AARCH64_LINUX_SIZEOF_GCS_REGSET (3 * 8) #endif /* GDB_ARCH_AARCH64_GCS_LINUX_H */ diff --git a/gdbsupport/config.in b/gdbsupport/config.in index 0beacf22c05..2957ee0f030 100644 --- a/gdbsupport/config.in +++ b/gdbsupport/config.in @@ -271,6 +271,9 @@ /* Define to 1 if `st_blocks' is a member of `struct stat'. */ #undef HAVE_STRUCT_STAT_ST_BLOCKS +/* Define to 1 if your system has struct user_gcs. */ +#undef HAVE_STRUCT_USER_GCS + /* Define to 1 if you have the header file. */ #undef HAVE_SYS_PARAM_H diff --git a/gdbsupport/configure b/gdbsupport/configure index 133ddfa7f6c..66135791aa5 100755 --- a/gdbsupport/configure +++ b/gdbsupport/configure @@ -14307,6 +14307,42 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu +# Check for `struct user_gcs` +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for struct user_gcs" >&5 +$as_echo_n "checking for struct user_gcs... " >&6; } +if ${gdb_cv_struct_user_gcs+:} false; then : + $as_echo_n "(cached) " >&6 +else + cat confdefs.h - <<_ACEOF >conftest.$ac_ext +/* end confdefs.h. */ +#include + #include +int +main () +{ +struct user_gcs u; + + ; + return 0; +} +_ACEOF +if ac_fn_c_try_compile "$LINENO"; then : + gdb_cv_struct_user_gcs=yes +else + gdb_cv_struct_user_gcs=no + +fi +rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext + +fi +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gdb_cv_struct_user_gcs" >&5 +$as_echo "$gdb_cv_struct_user_gcs" >&6; } +if test "$gdb_cv_struct_user_gcs" = yes; then + +$as_echo "#define HAVE_STRUCT_USER_GCS 1" >>confdefs.h + +fi + # Set the 'development' global. . $srcdir/../bfd/development.sh diff --git a/gdbsupport/configure.ac b/gdbsupport/configure.ac index b7ccfabd6c6..d3b4c05daeb 100644 --- a/gdbsupport/configure.ac +++ b/gdbsupport/configure.ac @@ -68,6 +68,25 @@ GDB_AC_PTRACE AM_GDB_COMPILER_TYPE AM_GDB_WARNINGS +# Check for `struct user_gcs` +AC_CACHE_CHECK( + [for struct user_gcs], + [gdb_cv_struct_user_gcs], + [AC_COMPILE_IFELSE( + [AC_LANG_PROGRAM( + [#include + #include ], + [struct user_gcs u;] + )], + [gdb_cv_struct_user_gcs=yes], + [gdb_cv_struct_user_gcs=no] + )] +) +if test "$gdb_cv_struct_user_gcs" = yes; then + AC_DEFINE(HAVE_STRUCT_USER_GCS, 1, + [Define to 1 if your system has struct user_gcs.]) +fi + # Set the 'development' global. . $srcdir/../bfd/development.sh -- 2.49.0