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glibc/ulp-prologue-into-asm-functions.patch
Andreas Schwab 833e55e71d Accepting request 1172774 from home:gbelinassi:branches:Base:System 
- ulp-prologue-into-asm-functions.patch: Avoid creating ULP prologue
for _start routine (bsc#1221940

OBS-URL: https://build.opensuse.org/request/show/1172774
OBS-URL: https://build.opensuse.org/package/show/Base:System/glibc?expand=0&rev=708
2024-05-14 09:33:16 +00:00

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From ec4f0a28ed48c51165e3e72c7427efb0ae14a124 Mon Sep 17 00:00:00 2001
From: Giuliano Belinassi <gbelinassi@suse.de>
Date: Mon, 6 May 2024 20:09:55 -0300
Subject: [PATCH] Add Userspace Livepatch prologue into ASM functions
Userspace Live Patching (ULP) refers to the process of applying
patches to the libraries used by a running process, without
interrupting it. In order to archive this, functions must have
the NOP prologue. This prologue is included automatically when
compiled with -fpatchable-function-entry, but for ASM functions
this have to be included manually. This patch does this.
Signed-off-by: Giuliano Belinassi <gbelinassi@suse.de>
---
Makeconfig | 5 +++
config.h.in | 3 ++
config.make.in | 1 +
configure | 21 +++++++++
configure.ac | 13 ++++++
sysdeps/x86_64/multiarch/strcmp-avx2.S | 5 +--
sysdeps/x86_64/multiarch/strcmp-evex.S | 5 +--
sysdeps/x86_64/multiarch/strcmp-sse4_2.S | 5 +--
sysdeps/x86_64/sysdep.h | 54 ++++++++++++++++++++++--
9 files changed, 96 insertions(+), 16 deletions(-)
diff --git a/Makeconfig b/Makeconfig
index e583765712..b136e10224 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -981,6 +981,11 @@ else
+cflags += $(no-fortify-source)
endif
+# Add flags for Userspace Livepatching support.
+ifeq (yes,$(enable-userspace-livepatch))
++cflags += -fpatchable-function-entry=16,14
+endif
+
# Each sysdeps directory can contain header files that both will be
# used to compile and will be installed. Each can also contain an
# include/ subdirectory, whose header files will be used to compile
diff --git a/config.h.in b/config.h.in
index c4cc7d3b9a..dc70ed03d0 100644
--- a/config.h.in
+++ b/config.h.in
@@ -205,6 +205,9 @@
/* Define to 1 if libpthread actually resides in libc. */
#define PTHREAD_IN_LIBC 0
+/* Define to 1 if support for userspace livepatching is enabled. */
+#define ENABLE_USERSPACE_LIVEPATCH 0
+
/* An integer used to scale the timeout of test programs. */
#define TIMEOUTFACTOR 1
diff --git a/config.make.in b/config.make.in
index 55e8b7563b..0f14c05d62 100644
--- a/config.make.in
+++ b/config.make.in
@@ -81,6 +81,7 @@ mach-interface-list = @mach_interface_list@
memory-tagging = @memory_tagging@
# Configuration options.
+enable-userspace-livepatch = @enable_userspace_livepatch@
build-shared = @shared@
build-profile = @profile@
build-static-nss = @static_nss@
diff --git a/configure b/configure
index 432e40a592..eb6b203925 100755
--- a/configure
+++ b/configure
@@ -622,6 +622,7 @@ LIBOBJS
pthread_in_libc
RELEASE
VERSION
+enable_userspace_livepatch
mach_interface_list
DEFINES
static_nss
@@ -812,6 +813,7 @@ enable_cet
enable_scv
enable_fortify_source
with_cpu
+enable_userspace_livepatch
'
ac_precious_vars='build_alias
host_alias
@@ -1490,6 +1492,8 @@ Optional Features:
Use -D_FORTIFY_SOURCE=[1|2|3] to control code
hardening, defaults to highest possible value
supported by the build compiler.
+ --enable-userspace-livepatch
+ build with userspace livepatch support [default=no]
Optional Packages:
--with-PACKAGE[=ARG] use PACKAGE [ARG=yes]
@@ -7867,6 +7871,23 @@ libc_cv_multidir=`${CC-cc} $CFLAGS $CPPFLAGS -print-multi-directory`
+# Check whether --enable-userspace-livepatch was given.
+if test ${enable_userspace_livepatch+y}
+then :
+ enableval=$enable_userspace_livepatch; enable_userspace_livepatch=$enableval
+else $as_nop
+ enable_userspace_livepatch=no
+fi
+
+
+# Libpulp uses -fpatchable-function-entry to add padding NOPS to the
+# prologue of all functions.
+if test "x$enable_userspace_livepatch" = xyes; then
+ printf "%s\n" "#define ENABLE_USERSPACE_LIVEPATCH 1" >>confdefs.h
+
+fi
+
+
VERSION=`sed -n -e 's/^#define VERSION "\([^"]*\)"/\1/p' < $srcdir/version.h`
RELEASE=`sed -n -e 's/^#define RELEASE "\([^"]*\)"/\1/p' < $srcdir/version.h`
diff --git a/configure.ac b/configure.ac
index bdc385d03c..cb4d28b3d8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1756,6 +1756,19 @@ AC_SUBST(DEFINES)
dnl See sysdeps/mach/configure.ac for this variable.
AC_SUBST(mach_interface_list)
+AC_ARG_ENABLE([userspace-livepatch],
+ AS_HELP_STRING([--enable-userspace-livepatch],
+ [build with userspace livepatch support @<:@default=no@:>@]),
+ [enable_userspace_livepatch=$enableval],
+ [enable_userspace_livepatch=no])
+
+# Libpulp uses -fpatchable-function-entry to add padding NOPS to the
+# prologue of all functions.
+if test "x$enable_userspace_livepatch" = xyes; then
+ AC_DEFINE(ENABLE_USERSPACE_LIVEPATCH)
+fi
+AC_SUBST(enable_userspace_livepatch)
+
VERSION=`sed -n -e 's/^#define VERSION "\([^"]*\)"/\1/p' < $srcdir/version.h`
RELEASE=`sed -n -e 's/^#define RELEASE "\([^"]*\)"/\1/p' < $srcdir/version.h`
AC_SUBST(VERSION)
diff --git a/sysdeps/x86_64/multiarch/strcmp-avx2.S b/sysdeps/x86_64/multiarch/strcmp-avx2.S
index 5bc1d90078..3ea96c0aa3 100644
--- a/sysdeps/x86_64/multiarch/strcmp-avx2.S
+++ b/sysdeps/x86_64/multiarch/strcmp-avx2.S
@@ -201,10 +201,7 @@ END (STRCASECMP)
# endif
.p2align 4
-STRCMP:
- cfi_startproc
- _CET_ENDBR
- CALL_MCOUNT
+FUNCTION_START(STRCMP)
# if defined USE_AS_STRCASECMP_L
/* We have to fall back on the C implementation for locales with
diff --git a/sysdeps/x86_64/multiarch/strcmp-evex.S b/sysdeps/x86_64/multiarch/strcmp-evex.S
index 06730ab2a1..d96b1c4824 100644
--- a/sysdeps/x86_64/multiarch/strcmp-evex.S
+++ b/sysdeps/x86_64/multiarch/strcmp-evex.S
@@ -224,10 +224,7 @@ END (STRCASECMP)
# endif
.p2align 4
-STRCMP:
- cfi_startproc
- _CET_ENDBR
- CALL_MCOUNT
+FUNCTION_START(STRCMP)
# if defined USE_AS_STRCASECMP_L
/* We have to fall back on the C implementation for locales with
diff --git a/sysdeps/x86_64/multiarch/strcmp-sse4_2.S b/sysdeps/x86_64/multiarch/strcmp-sse4_2.S
index 4e98da0246..2a2280c65f 100644
--- a/sysdeps/x86_64/multiarch/strcmp-sse4_2.S
+++ b/sysdeps/x86_64/multiarch/strcmp-sse4_2.S
@@ -103,10 +103,7 @@ END (STRCASECMP)
# define arg arg
-STRCMP:
- cfi_startproc
- _CET_ENDBR
- CALL_MCOUNT
+FUNCTION_START(STRCMP)
/*
* This implementation uses SSE to compare up to 16 bytes at a time.
diff --git a/sysdeps/x86_64/sysdep.h b/sysdeps/x86_64/sysdep.h
index db6e36b2dd..86a5d1b2be 100644
--- a/sysdeps/x86_64/sysdep.h
+++ b/sysdeps/x86_64/sysdep.h
@@ -49,6 +49,46 @@ enum cf_protection_level
#ifdef __ASSEMBLER__
+/* Libpulp uses -fpatchable-function-entry to add padding NOPS to the
+ prologue of all functions. This works for C functions. For functions
+ written in ASM, the way we do this is by adding this prologue manually. */
+
+#if ENABLE_USERSPACE_LIVEPATCH
+
+/* Instructions to be inserted before the function label. */
+# define ULP_NOPS_PRE_PROLOGUE .rept 14; nop; .endr
+
+/* Instruction to be inserted after the function label. */
+# define ULP_NOPS_POST_PROLOGUE .rept 2; nop; .endr
+
+
+/* this macro expands according to the following condition:
+ * if name = _start, then the prologue is not inserted.
+ * if name = _dl_relocate_static_pie, then the prologue is not inserted.
+ * if name = anything else, then the prologue is inserted.
+ **/
+# define __ULP_POST_PROLOGUE_dl_relocate_static_pie ,
+# define __ULP_PRE_PROLOGUE_start ,
+# define __ULP_PRE_PROLOGUE(x, y,...) y
+# define _ULP_PRE_PROLOGUE(x, ...) __ULP_PRE_PROLOGUE(x, __VA_ARGS__)
+# define ULP_PRE_PROLOGUE(name) _ULP_PRE_PROLOGUE(__ULP_PRE_PROLOGUE##name, ULP_NOPS_PRE_PROLOGUE,)
+
+/* this macro expands according to the following condition:
+ * if name = _start, then the postlogue is not inserted.
+ * if name = _dl_relocate_static_pie, then the postlogue is not inserted.
+ * if name = anything else, then the postlogue is inserted.
+ **/
+# define __ULP_POST_PROLOGUE_dl_relocate_static_pie ,
+# define __ULP_POST_PROLOGUE_start ,
+# define __ULP_POST_PROLOGUE(x, y,...) y
+# define _ULP_POST_PROLOGUE(x, ...) __ULP_POST_PROLOGUE(x, __VA_ARGS__)
+# define ULP_POST_PROLOGUE(name) _ULP_POST_PROLOGUE(__ULP_POST_PROLOGUE##name, ULP_NOPS_POST_PROLOGUE,)
+
+#else
+# define ULP_PRE_PROLOGUE(name)
+# define ULP_POST_PROLOGUE(name)
+#endif
+
/* Syntactic details of assembler. */
#ifdef _CET_ENDBR
@@ -58,15 +98,21 @@ enum cf_protection_level
# define _CET_NOTRACK
#endif
+/* Define the first instructions of a function. */
+#define FUNCTION_START(name) \
+ ULP_PRE_PROLOGUE(name); \
+ C_LABEL(name); \
+ cfi_startproc; \
+ _CET_ENDBR; \
+ ULP_POST_PROLOGUE(name); \
+ CALL_MCOUNT;
+
/* Define an entry point visible from C. */
#define ENTRY_P2ALIGN(name, alignment) \
.globl C_SYMBOL_NAME(name); \
.type C_SYMBOL_NAME(name),@function; \
.align ALIGNARG(alignment); \
- C_LABEL(name) \
- cfi_startproc; \
- _CET_ENDBR; \
- CALL_MCOUNT
+ FUNCTION_START(name)
/* This macro is for setting proper CFI with DW_CFA_expression describing
the register as saved relative to %rsp instead of relative to the CFA.
--
2.44.0
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