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elf: Handle static PIE with non-zero load address [BZ #31799]
For a static PIE with non-zero load address, its PT_DYNAMIC segment entries contain the relocated values for the load address in static PIE. Since static PIE usually doesn't have PT_PHDR segment, use p_vaddr of the PT_LOAD segment with offset == 0 as the load address in static PIE and adjust the entries of PT_DYNAMIC segment in static PIE by properly setting the l_addr field for static PIE. This fixes BZ #31799. Signed-off-by: H.J. Lu <hjl.tools@gmail.com> Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
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H.J. Lu
parent
713d6d7e78
commit
e7b5532721
74
configure
vendored
74
configure
vendored
@ -8107,6 +8107,80 @@ printf "%s\n" "$libc_cv_cc_pie_default" >&6; }
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config_vars="$config_vars
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cc-pie-default = $libc_cv_cc_pie_default"
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# Get Position Dependent Executable (PDE) load address to be used to
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# load static Position Independent Executable (PIE) at a known working
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# non-zero load address. This is only used by glibc tests to verify
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# that PIE and static PIE with non-zero load address work correctly.
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{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking PDE load address" >&5
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printf %s "checking PDE load address... " >&6; }
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if test ${libc_cv_pde_load_address+y}
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then :
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printf %s "(cached) " >&6
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else case e in #(
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e) cat > conftest.S <<EOF
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.globl _start
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_start:
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.globl __start
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__start:
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EOF
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if test $libc_cv_cc_pie_default = yes; then
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pde_ld_flags="-no-pie"
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fi
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if ${CC-cc} $pde_ld_flags $CFLAGS $CPPFLAGS $LDFLAGS \
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-nostartfiles -nostdlib $no_ssp \
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-o conftest conftest.S 1>&5 2>&5; then
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# Get the load address of the first PT_LOAD segment.
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libc_cv_pde_load_address=$(LC_ALL=C $READELF -Wl conftest \
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| $AWK '/LOAD/ { print $3; exit 0; }')
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else
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as_fn_error $? "${CC-cc} can not create PDE" "$LINENO" 5
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fi
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rm -f conftest* ;;
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esac
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fi
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{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $libc_cv_pde_load_address" >&5
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printf "%s\n" "$libc_cv_pde_load_address" >&6; }
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config_vars="$config_vars
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pde-load-address = $libc_cv_pde_load_address"
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# Get the linker command-line option to load executable at a non-zero
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# load address. This is only used by glibc tests to verify that PIE and
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# static PIE with non-zero load address work correctly.
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{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for linker that supports -Ttext-segment=$libc_cv_pde_load_address" >&5
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printf %s "checking for linker that supports -Ttext-segment=$libc_cv_pde_load_address... " >&6; }
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libc_linker_feature=no
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cat > conftest.c <<EOF
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int _start (void) { return 42; }
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EOF
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if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp
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-Wl,-Ttext-segment=$libc_cv_pde_load_address -nostdlib -nostartfiles
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-fPIC -shared -o conftest.so conftest.c
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1>&5'
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{ { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
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(eval $ac_try) 2>&5
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ac_status=$?
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printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
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test $ac_status = 0; }; }
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then
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if ${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp -Wl,-Ttext-segment=$libc_cv_pde_load_address -nostdlib \
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-nostartfiles -fPIC -shared -o conftest.so conftest.c 2>&1 \
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| grep "warning: -Ttext-segment=$libc_cv_pde_load_address ignored" > /dev/null 2>&1; then
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true
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else
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libc_linker_feature=yes
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fi
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fi
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rm -f conftest*
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if test $libc_linker_feature = yes; then
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libc_cv_load_address_ldflag=-Wl,-Ttext-segment
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else
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libc_cv_load_address_ldflag=
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fi
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{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5
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printf "%s\n" "$libc_linker_feature" >&6; }
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config_vars="$config_vars
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load-address-ldflag = $libc_cv_load_address_ldflag"
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{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking if we can build programs as PIE" >&5
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printf %s "checking if we can build programs as PIE... " >&6; }
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cat confdefs.h - <<_ACEOF >conftest.$ac_ext
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36
configure.ac
36
configure.ac
@ -1763,6 +1763,42 @@ fi
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rm -f conftest.*])
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LIBC_CONFIG_VAR([cc-pie-default], [$libc_cv_cc_pie_default])
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# Get Position Dependent Executable (PDE) load address to be used to
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# load static Position Independent Executable (PIE) at a known working
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# non-zero load address. This is only used by glibc tests to verify
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# that PIE and static PIE with non-zero load address work correctly.
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AC_CACHE_CHECK([PDE load address],
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libc_cv_pde_load_address, [dnl
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cat > conftest.S <<EOF
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.globl _start
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_start:
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.globl __start
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__start:
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EOF
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if test $libc_cv_cc_pie_default = yes; then
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pde_ld_flags="-no-pie"
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fi
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if ${CC-cc} $pde_ld_flags $CFLAGS $CPPFLAGS $LDFLAGS \
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-nostartfiles -nostdlib $no_ssp \
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-o conftest conftest.S 1>&AS_MESSAGE_LOG_FD 2>&AS_MESSAGE_LOG_FD; then
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# Get the load address of the first PT_LOAD segment.
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libc_cv_pde_load_address=$(LC_ALL=C $READELF -Wl conftest \
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| $AWK '/LOAD/ { print $3; exit 0; }')
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else
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AC_MSG_ERROR([${CC-cc} can not create PDE])
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fi
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rm -f conftest*])
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LIBC_CONFIG_VAR([pde-load-address], [$libc_cv_pde_load_address])
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# Get the linker command-line option to load executable at a non-zero
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# load address. This is only used by glibc tests to verify that PIE and
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# static PIE with non-zero load address work correctly.
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LIBC_LINKER_FEATURE([-Ttext-segment=$libc_cv_pde_load_address],
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[-Wl,-Ttext-segment=$libc_cv_pde_load_address],
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[libc_cv_load_address_ldflag=-Wl,-Ttext-segment],
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[libc_cv_load_address_ldflag=])
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LIBC_CONFIG_VAR([load-address-ldflag], [$libc_cv_load_address_ldflag])
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AC_MSG_CHECKING(if we can build programs as PIE)
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AC_COMPILE_IFELSE([AC_LANG_SOURCE([[#ifdef PIE_UNSUPPORTED
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# error PIE is not supported
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20
elf/Makefile
20
elf/Makefile
@ -1091,6 +1091,25 @@ tests-pie += \
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tst-pie1 \
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tst-pie2 \
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# tests-pie
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ifneq (,$(load-address-ldflag))
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tests += \
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tst-pie-address \
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# tests
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tests-pie += \
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tst-pie-address \
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# tests-pie
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LDFLAGS-tst-pie-address += $(load-address-ldflag)=$(pde-load-address)
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ifeq (yes,$(enable-static-pie))
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tests += \
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tst-pie-address-static \
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# tests
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tests-static += \
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tst-pie-address-static \
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# tests-static
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LDFLAGS-tst-pie-address-static += \
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$(load-address-ldflag)=$(pde-load-address)
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endif
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endif
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ifeq (yes,$(have-protected-data))
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tests += vismain
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tests-pie += vismain
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@ -1937,6 +1956,7 @@ $(objpfx)tst-array5-static-cmp.out: tst-array5-static.exp \
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CFLAGS-tst-pie1.c += $(pie-ccflag)
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CFLAGS-tst-pie2.c += $(pie-ccflag)
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CFLAGS-tst-pie-address.c += $(pie-ccflag)
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$(objpfx)tst-piemod1.so: $(libsupport)
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$(objpfx)tst-pie1: $(objpfx)tst-piemod1.so
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@ -37,21 +37,37 @@ _dl_relocate_static_pie (void)
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{
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struct link_map *main_map = _dl_get_dl_main_map ();
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/* Figure out the run-time load address of static PIE. */
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main_map->l_addr = elf_machine_load_address ();
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/* Read our own dynamic section and fill in the info array. */
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main_map->l_ld = ((void *) main_map->l_addr + elf_machine_dynamic ());
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/* NB: elf_machine_load_address () returns the run-time load address
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of static PIE. The l_addr field contains the difference between the
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link-time load address in the ELF file and the run-time load address
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in memory. We must subtract the link-time load address of static PIE,
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which can be non-zero, when computing the l_addr field. Since static
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PIE usually doesn't have PT_PHDR segment, use p_vaddr of the PT_LOAD
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segment with offset == 0 as the load address of static PIE. */
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ElfW(Addr) file_p_vaddr = 0;
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const ElfW(Phdr) *ph, *phdr = GL(dl_phdr);
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size_t phnum = GL(dl_phnum);
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for (ph = phdr; ph < &phdr[phnum]; ++ph)
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if (ph->p_type == PT_DYNAMIC)
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switch (ph->p_type)
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{
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case PT_LOAD:
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if (ph->p_offset == 0)
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file_p_vaddr = ph->p_vaddr;
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break;
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case PT_DYNAMIC:
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main_map->l_ld_readonly = (ph->p_flags & PF_W) == 0;
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break;
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default:
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break;
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}
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/* Figure out the run-time load address of static PIE. */
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ElfW(Addr) l_addr = elf_machine_load_address ();
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main_map->l_addr = l_addr - file_p_vaddr;
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/* Read our own dynamic section and fill in the info array. */
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main_map->l_ld = ((void *) l_addr + elf_machine_dynamic ());
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elf_get_dynamic_info (main_map, false, true);
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# ifdef ELF_MACHINE_BEFORE_RTLD_RELOC
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19
elf/tst-pie-address-static.c
Normal file
19
elf/tst-pie-address-static.c
Normal file
@ -0,0 +1,19 @@
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/* Test static PIE with non-zero load address.
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Copyright (C) 2024 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include "tst-pie-address.c"
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28
elf/tst-pie-address.c
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28
elf/tst-pie-address.c
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@ -0,0 +1,28 @@
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/* Test PIE with non-zero load address.
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Copyright (C) 2024 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <stdio.h>
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static int
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do_test (void)
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{
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printf ("Hello\n");
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return 0;
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}
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#include <support/test-driver.c>
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