From: Aurelien Jarno <aurelien@aurel32.net>
Date: Sat, 26 Oct 2024 20:41:09 +0000 (+0200)
Subject: [PATCH] Revert "AArch64: Check kernel version for SVE ifuncs"
X-Git-Tag: archive/raspbian/2.36-9+rpi1+deb12u13^2~84
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=571fbeafa9d06af9517cc321c020aa1b64969a93;p=glibc.git

[PATCH] Revert "AArch64: Check kernel version for SVE ifuncs"

This reverts commit 24de733967029fd902c34073d2ab25b900887352.

Gbp-Pq: Topic arm64
Gbp-Pq: Name local-revert-aarch64-check-kernel-version-for-sve-ifuncs.diff
---

diff --git a/sysdeps/aarch64/multiarch/init-arch.h b/sysdeps/aarch64/multiarch/init-arch.h
index 5b2cf5cb1..5da165695 100644
--- a/sysdeps/aarch64/multiarch/init-arch.h
+++ b/sysdeps/aarch64/multiarch/init-arch.h
@@ -36,7 +36,5 @@
     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 3de66c14d..d1cf5bec1 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 prefer_sve_ifuncs ? __memcpy_sve : __memcpy_generic;
+      return __memcpy_sve;
     }
 
   if (IS_THUNDERX (midr))
diff --git a/sysdeps/aarch64/multiarch/memmove.c b/sysdeps/aarch64/multiarch/memmove.c
index fdcf41882..90729e027 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 prefer_sve_ifuncs ? __memmove_sve : __memmove_generic;
+      return __memmove_sve;
     }
 
   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 254312835..6ee1cb4bc 100644
--- a/sysdeps/unix/sysv/linux/aarch64/cpu-features.c
+++ b/sysdeps/unix/sysv/linux/aarch64/cpu-features.c
@@ -20,7 +20,6 @@
 #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)
@@ -60,46 +59,6 @@ get_midr_from_mcpu (const char *mcpu)
 }
 #endif
 
-#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)
 {
@@ -166,13 +125,6 @@ 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 d51597b92..b4bd43a22 100644
--- a/sysdeps/unix/sysv/linux/aarch64/cpu-features.h
+++ b/sysdeps/unix/sysv/linux/aarch64/cpu-features.h
@@ -71,7 +71,6 @@ 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;
 };