File ulp-prologue-into-asm-functions.patch of Package glibc
From 17d77e73d882f341784da2957b7334566c48f8ad Mon Sep 17 00:00:00 2001
From: Giuliano Belinassi <gbelinassi@suse.de>
Date: Wed, 24 May 2023 18:03:15 -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 | 20 ++++++++++++++++++++
configure.ac | 13 +++++++++++++
sysdeps/x86/sysdep.h | 24 +++++++++++++++++++-----
sysdeps/x86_64/sysdep.h | 26 ++++++++++++++++++++++++++
7 files changed, 87 insertions(+), 5 deletions(-)
diff --git a/Makeconfig b/Makeconfig
index f252842979..1700ae6fb0 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -916,6 +916,11 @@ endif # $(+cflags) == ""
$(+stack-protector)
+gcc-nowarn := -w
+# Add flags for Userspace Livepatching support.
+ifeq (yes,$(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 dea43df438..f379201aec 100644
--- a/config.h.in
+++ b/config.h.in
@@ -186,6 +186,9 @@
/* Define if the linker defines __ehdr_start. */
#undef HAVE_EHDR_START
+/* Define to 1 if support for userspace livepatching is enabled. */
+#define ENABLE_USERSPACE_LIVEPATCH 0
+
/*
*/
diff --git a/config.make.in b/config.make.in
index 2fed3da773..1ed8bcc786 100644
--- a/config.make.in
+++ b/config.make.in
@@ -88,6 +88,7 @@ nss-crypt = @libc_cv_nss_crypt@
static-nss-crypt = @libc_cv_static_nss_crypt@
# Configuration options.
+enable-userspace-livepatch = @enable_userspace_livepatch@
build-shared = @shared@
build-pic-default= @libc_cv_pic_default@
build-pie-default= @libc_cv_pie_default@
diff --git a/configure b/configure
index 3b98ec312f..95de3f637f 100755
--- a/configure
+++ b/configure
@@ -590,6 +590,7 @@ ac_subst_vars='LTLIBOBJS
LIBOBJS
RELEASE
VERSION
+enable_userspace_livepatch
mach_interface_list
DEFINES
static_nss
@@ -795,6 +796,7 @@ enable_tunables
enable_mathvec
enable_cet
with_cpu
+enable_userspace_livepatch
'
ac_precious_vars='build_alias
host_alias
@@ -1471,6 +1473,8 @@ Optional Features:
depends on architecture]
--enable-cet enable Intel Control-flow Enforcement Technology
(CET), x86 only
+ --enable-userspace-livepatch
+ build with userspace livepatch support [default=no]
Optional Packages:
--with-PACKAGE[=ARG] use PACKAGE [ARG=yes]
@@ -6918,6 +6922,22 @@ enable-static-pie = $static_pie"
+# Check whether --enable-userspace-livepatch was given.
+if test "${enable_userspace_livepatch+set}" = set; then :
+ enableval=$enable_userspace_livepatch; enable_userspace_livepatch=$enableval
+else
+ 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
+ $as_echo "#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' < $srcdir/version.h`
diff --git a/configure.ac b/configure.ac
index e20034f301..a9bcf62681 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1896,6 +1896,19 @@ AC_SUBST(DEFINES)
dnl See sysdeps/mach/configure.ac for this variable.
AC_SUBST(mach_interface_list)
+AC_ARG_ENABLE([userspace-livepatch],
+ AS_HELP_STRING([--enable-userspace-livepatch],
+ [build with userspace livepatch support @<:@default=no@:>@]),
+ [enable_userspace_livepatch=$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/sysdep.h b/sysdeps/x86/sysdep.h
index f5039bc1b2..94749327c2 100644
--- a/sysdeps/x86/sysdep.h
+++ b/sysdeps/x86/sysdep.h
@@ -72,15 +72,29 @@ enum cf_protection_level
#define ALIGNARG(log2) 1<<log2
#define ASM_SIZE_DIRECTIVE(name) .size name,.-name;
+/* For 32-bit glibc then define those macros as empty. */
+#ifndef ULP_PRE_PROLOGUE
+# define ULP_PRE_PROLOGUE
+#endif
+#ifndef ULP_POST_PROLOGUE
+# define ULP_POST_PROLOGUE
+#endif
+
+/* Define the first instructions of a function. */
+#define FUNCTION_START(name) \
+ ULP_PRE_PROLOGUE; \
+ C_LABEL(name); \
+ cfi_startproc; \
+ _CET_ENDBR; \
+ ULP_POST_PROLOGUE; \
+ CALL_MCOUNT;
+
/* Define an entry point visible from C. */
#define ENTRY(name) \
.globl C_SYMBOL_NAME(name); \
.type C_SYMBOL_NAME(name),@function; \
- .align ALIGNARG(4); \
- C_LABEL(name) \
- cfi_startproc; \
- _CET_ENDBR; \
- CALL_MCOUNT
+ .align ALIGNARG(4); \
+ FUNCTION_START(name)
#undef END
#define END(name) \
diff --git a/sysdeps/x86_64/sysdep.h b/sysdeps/x86_64/sysdep.h
index c8ad778fee..0eb6cf2d81 100644
--- a/sysdeps/x86_64/sysdep.h
+++ b/sysdeps/x86_64/sysdep.h
@@ -23,6 +23,32 @@
#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 == 1
+# undef ULP_PRE_PROLOGUE
+# undef ULP_POST_PROLOGUE
+# define ULP_PRE_PROLOGUE \
+ nop; \
+ nop; \
+ nop; \
+ nop; \
+ nop; \
+ nop; \
+ nop; \
+ nop; \
+ nop; \
+ nop; \
+ nop; \
+ nop; \
+ nop; \
+ nop;
+# define ULP_POST_PROLOGUE \
+ xchg %ax, %ax
+#endif
+
/* Syntactic details of assembler. */
/* This macro is for setting proper CFI with DW_CFA_expression describing
--
2.39.0
