[PATCH] x86: Define MINIMUM_X86_ISA_LEVEL in config.h [BZ #31676]

[PATCH] x86: Define MINIMUM_X86_ISA_LEVEL in config.h [BZ #31676]

[H.J. Lu]

Define MINIMUM_X86_ISA_LEVEL at configure time to avoid

/usr/bin/ld: …/build/elf/librtld.os: in function `init_cpu_features':
…/git/elf/../sysdeps/x86/cpu-features.c:1202: undefined reference to `_dl_runtime_resolve_fxsave'
/usr/bin/ld: …/build/elf/librtld.os: relocation R_X86_64_PC32 against undefined hidden symbol `_dl_runtime_resolve_fxsave' can not be used when making a shared object
/usr/bin/ld: final link failed: bad value
collect2: error: ld returned 1 exit status

when glibc is built with -march=x86-64-v3 and configured with
--with-rtld-early-cflags=-march=x86-64, which is used to allow ld.so to
print an error message on unsupported CPUs:

Fatal glibc error: CPU does not support x86-64-v3

This fixes BZ #31676.
---
 config.h.in              | 3 +++
 sysdeps/x86/configure    | 7 +++++++
 sysdeps/x86/configure.ac | 5 +++++
 sysdeps/x86/isa-level.h  | 4 +++-
 4 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/config.h.in b/config.h.in
index 69ac450356..ac5a68b405 100644
--- a/config.h.in
+++ b/config.h.in
@@ -285,6 +285,9 @@
 /* Define if x86 ISA level should be included in shared libraries.  */
 #undef INCLUDE_X86_ISA_LEVEL
 
+/* The x86 ISA level.  0 for baseline.  Undefined on non-x86.  */
+#undef MINIMUM_X86_ISA_LEVEL
+
 /* Define if -msahf is enabled by default on x86.  */
 #undef HAVE_X86_LAHF_SAHF
 
diff --git a/sysdeps/x86/configure b/sysdeps/x86/configure
index 2a5421bb31..d28d9bcb29 100644
--- a/sysdeps/x86/configure
+++ b/sysdeps/x86/configure
@@ -151,6 +151,13 @@ printf "%s\n" "$libc_cv_have_x86_isa_level" >&6; }
 else
   libc_cv_have_x86_isa_level=baseline
 fi
+if test $libc_cv_have_x86_isa_level = baseline; then
+  printf "%s\n" "#define MINIMUM_X86_ISA_LEVEL 1" >>confdefs.h
+
+else
+  printf "%s\n" "#define MINIMUM_X86_ISA_LEVEL $libc_cv_have_x86_isa_level" >>confdefs.h
+
+fi
 config_vars="$config_vars
 have-x86-isa-level = $libc_cv_have_x86_isa_level"
 config_vars="$config_vars
diff --git a/sysdeps/x86/configure.ac b/sysdeps/x86/configure.ac
index 78ff7c8f41..5b0acd03d2 100644
--- a/sysdeps/x86/configure.ac
+++ b/sysdeps/x86/configure.ac
@@ -105,6 +105,11 @@ EOF
 else
   libc_cv_have_x86_isa_level=baseline
 fi
+if test $libc_cv_have_x86_isa_level = baseline; then
+  AC_DEFINE_UNQUOTED(MINIMUM_X86_ISA_LEVEL, 1)
+else
+  AC_DEFINE_UNQUOTED(MINIMUM_X86_ISA_LEVEL, $libc_cv_have_x86_isa_level)
+fi
 LIBC_CONFIG_VAR([have-x86-isa-level], [$libc_cv_have_x86_isa_level])
 LIBC_CONFIG_VAR([x86-isa-level-3-or-above], [3 4])
 LIBC_CONFIG_VAR([enable-x86-isa-level], [$libc_cv_include_x86_isa_level])
diff --git a/sysdeps/x86/isa-level.h b/sysdeps/x86/isa-level.h
index 11fe1ca90c..2c7f74212b 100644
--- a/sysdeps/x86/isa-level.h
+++ b/sysdeps/x86/isa-level.h
@@ -61,8 +61,10 @@
 # define __X86_ISA_V4 0
 #endif
 
-#define MINIMUM_X86_ISA_LEVEL                                                 \
+#ifndef MINIMUM_X86_ISA_LEVEL
+# define MINIMUM_X86_ISA_LEVEL                                                 \
   (__X86_ISA_V1 + __X86_ISA_V2 + __X86_ISA_V3 + __X86_ISA_V4)
+#endif
 
 /* Depending on the minimum ISA level, a feature check result can be a
    compile-time constant.. */
-- 
2.44.0

Re: [PATCH] x86: Define MINIMUM_X86_ISA_LEVEL in config.h [BZ #31676]

[Andreas Schwab]

On Apr 23 2024, H.J. Lu wrote:

> +/* The x86 ISA level.  0 for baseline.  Undefined on non-x86.  */

> +if test $libc_cv_have_x86_isa_level = baseline; then
> +  AC_DEFINE_UNQUOTED(MINIMUM_X86_ISA_LEVEL, 1)

That doesn't fit together.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."