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b46c1c0b2e
glibc/glibc-upstream-2.39-25.patch
Arjun Shankar b88a2e4886 Sync with upstream branch release/2.39/master (RHEL-31801) 
Upstream commit: 31da30f23cddd36db29d5b6a1c7619361b271fb4

- iconv: ISO-2022-CN-EXT: fix out-of-bound writes when writing escape sequence (CVE-2024-2961)

Resolves: RHEL-31801

- x86_64: Exclude SSE, AVX and FMA4 variants in libm multiarch
- Apply the Makefile sorting fix
- powerpc: Fix ld.so address determination for PCREL mode (bug 31640)
- x86-64: Simplify minimum ISA check ifdef conditional with if
- x86-64: Don't use SSE resolvers for ISA level 3 or above
- AArch64: Check kernel version for SVE ifuncs
- aarch64: fix check for SVE support in assembler
- aarch64/fpu: Sync libmvec routines from 2.39 and before with AOR
- i386: Use generic memrchr in libc (bug 31316)

Related: RHEL-35602

Fedora 40 commit: 1bea1361dc
2024-06-07 16:25:50 +02:00

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5.1 KiB
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commit 9d92452c70805a2e2dbbdb2b1ffc34bd86e1c8df
Author: Wilco Dijkstra <wilco.dijkstra@arm.com>
Date: Thu Mar 21 16:48:33 2024 +0000
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)
diff --git a/sysdeps/aarch64/cpu-features.h b/sysdeps/aarch64/cpu-features.h
index 77a782422af1b6e4..5f2da91ebbd0adaf 100644
--- a/sysdeps/aarch64/cpu-features.h
+++ b/sysdeps/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;
};
diff --git a/sysdeps/aarch64/multiarch/init-arch.h b/sysdeps/aarch64/multiarch/init-arch.h
index c52860efb22d70eb..61dc40088f4d9e5e 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 d12eccfca51f4bcf..ce53567dab33c2f0 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 2081eeb4d40e0240..fe95037be391896c 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 b1a3f673f067280b..c0b047bc0dbeae42 100644
--- a/sysdeps/unix/sysv/linux/aarch64/cpu-features.c
+++ b/sysdeps/unix/sysv/linux/aarch64/cpu-features.c
@@ -21,6 +21,7 @@
#include <sys/auxv.h>
#include <elf/dl-hwcaps.h>
#include <sys/prctl.h>
+#include <sys/utsname.h>
#include <dl-tunables-parse.h>
#define DCZID_DZP_MASK (1 << 4)
@@ -62,6 +63,46 @@ get_midr_from_mcpu (const struct tunable_str_t *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)
{
@@ -126,6 +167,13 @@ 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;
}
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