automatic import of glibcopeneuler20.03

1 files changed, 153 insertions, 0 deletions

diff --git a/0012-AArch64-Check-kernel-version-for-SVE-ifuncs.patch b/0012-AArch64-Check-kernel-version-for-SVE-ifuncs.patch
new file mode 100644
index 0000000..687c821
--- /dev/null
+++ b/0012-AArch64-Check-kernel-version-for-SVE-ifuncs.patch
@@ -0,0 +1,153 @@
+From 92da7c2cfeeea36d651142f47e570dd5076bc166 Mon Sep 17 00:00:00 2001
+From: Wilco Dijkstra <wilco.dijkstra@arm.com>
+Date: Thu, 21 Mar 2024 16:48:33 +0000
+Subject: [PATCH 12/26] AArch64: Check kernel version for SVE ifuncs
+
+Old Linux kernels disable SVE after every system call.  Calling the
+SVE-optimized memcpy afterwards will then cause a trap to reenable SVE.
+As a result, applications with a high use of syscalls may run slower with
+the SVE memcpy.  This is true for kernels between 4.15.0 and before 6.2.0,
+except for 5.14.0 which was patched.  Avoid this by checking the kernel
+version and selecting the SVE ifunc on modern kernels.
+
+Parse the kernel version reported by uname() into a 24-bit kernel.major.minor
+value without calling any library functions.  If uname() is not supported or
+if the version format is not recognized, assume the kernel is modern.
+
+Tested-by: Florian Weimer <fweimer@redhat.com>
+Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
+(cherry picked from commit 2e94e2f5d2bf2de124c8ad7da85463355e54ccb2)
+---
+ sysdeps/aarch64/multiarch/init-arch.h         |  2 +
+ sysdeps/aarch64/multiarch/memcpy.c            |  2 +-
+ sysdeps/aarch64/multiarch/memmove.c           |  2 +-
+ .../unix/sysv/linux/aarch64/cpu-features.c    | 48 +++++++++++++++++++
+ .../unix/sysv/linux/aarch64/cpu-features.h    |  1 +
+ 5 files changed, 53 insertions(+), 2 deletions(-)
+
+diff --git a/sysdeps/aarch64/multiarch/init-arch.h b/sysdeps/aarch64/multiarch/init-arch.h
+index e23e6ff290..daef631e04 100644
+--- a/sysdeps/aarch64/multiarch/init-arch.h
++++ b/sysdeps/aarch64/multiarch/init-arch.h
+@@ -36,5 +36,7 @@
+     MTE_ENABLED ();							      \
+   bool __attribute__((unused)) sve =					      \
+     GLRO(dl_aarch64_cpu_features).sve;					      \
++  bool __attribute__((unused)) prefer_sve_ifuncs =			      \
++    GLRO(dl_aarch64_cpu_features).prefer_sve_ifuncs;			      \
+   bool __attribute__((unused)) mops =					      \
+     GLRO(dl_aarch64_cpu_features).mops;
+diff --git a/sysdeps/aarch64/multiarch/memcpy.c b/sysdeps/aarch64/multiarch/memcpy.c
+index 6471fe82e3..e7c7795db6 100644
+--- a/sysdeps/aarch64/multiarch/memcpy.c
++++ b/sysdeps/aarch64/multiarch/memcpy.c
+@@ -47,7 +47,7 @@ select_memcpy_ifunc (void)
+     {
+       if (IS_A64FX (midr))
+ 	return __memcpy_a64fx;
+-      return __memcpy_sve;
++      return prefer_sve_ifuncs ? __memcpy_sve : __memcpy_generic;
+     }
+ 
+   if (IS_THUNDERX (midr))
+diff --git a/sysdeps/aarch64/multiarch/memmove.c b/sysdeps/aarch64/multiarch/memmove.c
+index 7602a5d57d..6b77166851 100644
+--- a/sysdeps/aarch64/multiarch/memmove.c
++++ b/sysdeps/aarch64/multiarch/memmove.c
+@@ -47,7 +47,7 @@ select_memmove_ifunc (void)
+     {
+       if (IS_A64FX (midr))
+ 	return __memmove_a64fx;
+-      return __memmove_sve;
++      return prefer_sve_ifuncs ? __memmove_sve : __memmove_generic;
+     }
+ 
+   if (IS_THUNDERX (midr))
+diff --git a/sysdeps/unix/sysv/linux/aarch64/cpu-features.c b/sysdeps/unix/sysv/linux/aarch64/cpu-features.c
+index a11a86efab..4a205a6b35 100644
+--- a/sysdeps/unix/sysv/linux/aarch64/cpu-features.c
++++ b/sysdeps/unix/sysv/linux/aarch64/cpu-features.c
+@@ -20,6 +20,7 @@
+ #include <sys/auxv.h>
+ #include <elf/dl-hwcaps.h>
+ #include <sys/prctl.h>
++#include <sys/utsname.h>
+ 
+ #define DCZID_DZP_MASK (1 << 4)
+ #define DCZID_BS_MASK (0xf)
+@@ -57,6 +58,46 @@ get_midr_from_mcpu (const char *mcpu)
+   return UINT64_MAX;
+ }
+ 
++#if __LINUX_KERNEL_VERSION < 0x060200
++
++/* Return true if we prefer using SVE in string ifuncs.  Old kernels disable
++   SVE after every system call which results in unnecessary traps if memcpy
++   uses SVE.  This is true for kernels between 4.15.0 and before 6.2.0, except
++   for 5.14.0 which was patched.  For these versions return false to avoid using
++   SVE ifuncs.
++   Parse the kernel version into a 24-bit kernel.major.minor value without
++   calling any library functions.  If uname() is not supported or if the version
++   format is not recognized, assume the kernel is modern and return true.  */
++
++static inline bool
++prefer_sve_ifuncs (void)
++{
++  struct utsname buf;
++  const char *p = &buf.release[0];
++  int kernel = 0;
++  int val;
++
++  if (__uname (&buf) < 0)
++    return true;
++
++  for (int shift = 16; shift >= 0; shift -= 8)
++    {
++      for (val = 0; *p >= '0' && *p <= '9'; p++)
++	val = val * 10 + *p - '0';
++      kernel |= (val & 255) << shift;
++      if (*p++ != '.')
++	break;
++    }
++
++  if (kernel >= 0x060200 || kernel == 0x050e00)
++    return true;
++  if (kernel >= 0x040f00)
++    return false;
++  return true;
++}
++
++#endif
++
+ static inline void
+ init_cpu_features (struct cpu_features *cpu_features)
+ {
+@@ -119,6 +160,13 @@ init_cpu_features (struct cpu_features *cpu_features)
+   /* Check if SVE is supported.  */
+   cpu_features->sve = GLRO (dl_hwcap) & HWCAP_SVE;
+ 
++  cpu_features->prefer_sve_ifuncs = cpu_features->sve;
++
++#if __LINUX_KERNEL_VERSION < 0x060200
++  if (cpu_features->sve)
++    cpu_features->prefer_sve_ifuncs = prefer_sve_ifuncs ();
++#endif
++
+   /* Check if MOPS is supported.  */
+   cpu_features->mops = GLRO (dl_hwcap2) & HWCAP2_MOPS;
+ }
+diff --git a/sysdeps/unix/sysv/linux/aarch64/cpu-features.h b/sysdeps/unix/sysv/linux/aarch64/cpu-features.h
+index 2cf745cd19..351a619dcb 100644
+--- a/sysdeps/unix/sysv/linux/aarch64/cpu-features.h
++++ b/sysdeps/unix/sysv/linux/aarch64/cpu-features.h
+@@ -71,6 +71,7 @@ struct cpu_features
+   /* Currently, the GLIBC memory tagging tunable only defines 8 bits.  */
+   uint8_t mte_state;
+   bool sve;
++  bool prefer_sve_ifuncs;
+   bool mops;
+ };
+ 
+-- 
+2.33.0
+