From 3c0817dcbbc99eb438a33be5336db69cf88ca7cf Mon Sep 17 00:00:00 2001 From: Giuliano Belinassi 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 --- 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 | 28 ++++++++++++++++++++---- 9 files changed, 70 insertions(+), 16 deletions(-) diff --git a/Makeconfig b/Makeconfig index 85e00cef94..502e4e2d89 100644 --- a/Makeconfig +++ b/Makeconfig @@ -979,6 +979,11 @@ 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 44a34072a4..430627dcaf 100644 --- a/config.h.in +++ b/config.h.in @@ -199,6 +199,9 @@ /* 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 59ff1e415d..69c0795f99 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] @@ -7864,6 +7868,23 @@ 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' < $srcdir/version.h` diff --git a/configure.ac b/configure.ac index 65799e5685..e792f8c866 100644 --- a/configure.ac +++ b/configure.ac @@ -1753,6 +1753,19 @@ AC_SUBST(DEFINES) dnl See sysdeps/mach/configure.ac for this variable. AC_SUBST(mach_interface_list) +AC_ARG_ENABLE([userspace-livepatch], + AS_HELP_STRING([--enable-userspace-livepatch], + [build with userspace livepatch support @<:@default=no@:>@]), + [enable_userspace_livepatch=$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..37136d8ca9 100644 --- a/sysdeps/x86_64/sysdep.h +++ b/sysdeps/x86_64/sysdep.h @@ -49,6 +49,20 @@ 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 +# define ULP_PRE_PROLOGUE \ + .rept 14; nop; .endr +# define ULP_POST_PROLOGUE \ + xchg %ax, %ax +#else +# define ULP_PRE_PROLOGUE +# define ULP_POST_PROLOGUE +#endif + /* Syntactic details of assembler. */ #ifdef _CET_ENDBR @@ -58,15 +72,21 @@ enum cf_protection_level # define _CET_NOTRACK #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_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. -- 2.43.0