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Lu" To: gcc-patches@gcc.gnu.org Cc: Uros Bizjak , Jakub Jelinek , Richard Biener Subject: [PATCH v3 2/2] Add TARGET_ASM_EMIT_GNU_PROPERTY_NOTE Date: Fri, 9 Jul 2021 07:50:14 -0700 Message-Id: <20210709145014.1350564-3-hjl.tools@gmail.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210709145014.1350564-1-hjl.tools@gmail.com> References: <20210709145014.1350564-1-hjl.tools@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-3032.4 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, RCVD_IN_BARRACUDACENTRAL, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 09 Jul 2021 14:50:22 -0000 Generate the marker for -fno-direct-extern-access to indicate that the object file uses GOT to access all external symbols. Access to protected symbols in the resulting shared library is treated as local, which requires canonical function pointers and cannot be used with copy relocation. GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS support has been added to GNU binutils 2.38. But the -z indirect-extern-access linker option is only available for Linux/x86. However, the --max-cache-size=SIZE linker option was also addded within a day. --max-cache-size=SIZE is used to check for GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS support. This marker can be used in the following ways: 1. Linker can decide the best way to resolve a relocation against a protected symbol before seeing all relocations against the symbol. 2. Dynamic linker can decide if it is an error to have a copy relocation in executable against the protected symbol in a shared library by checking if the shared library is built with -fno-direct-extern-access. * configure.ac (HAVE_LD_INDIRECT_EXTERN_ACCESS_SUPPORT): New. Define to 1 if linker supports GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS. * output.h (emit_gnu_property): New. (emit_gnu_property_note): Likewise. * target.def (emit_gnu_property_note): Add a argetm.asm_out hook. * toplev.c (compile_file): Call emit_gnu_property_note before file_end. * varasm.c (emit_gnu_property): New. (emit_gnu_property_note): Likewise. * config.in: Regenerated. * configure: Likewise. * doc/tm.texi: Likewise. * config/i386/gnu-property.c (emit_gnu_property): Removed. (TARGET_ASM_EMIT_GNU_PROPERTY_NOTE): New. * doc/tm.texi.in: Add TARGET_ASM_EMIT_GNU_PROPERTY_NOTE. --- gcc/config.in | 7 +++++ gcc/config/i386/gnu-property.c | 31 ---------------------- gcc/config/i386/i386.c | 2 ++ gcc/configure | 26 +++++++++++++++++++ gcc/configure.ac | 22 ++++++++++++++++ gcc/doc/tm.texi | 5 ++++ gcc/doc/tm.texi.in | 2 ++ gcc/output.h | 2 ++ gcc/target.def | 8 ++++++ gcc/toplev.c | 3 +++ gcc/varasm.c | 47 ++++++++++++++++++++++++++++++++++ 11 files changed, 124 insertions(+), 31 deletions(-) diff --git a/gcc/config.in b/gcc/config.in index 2abac530c64..2c94a046de7 100644 --- a/gcc/config.in +++ b/gcc/config.in @@ -1652,6 +1652,13 @@ #endif +/* Define to 1 if your linker supports + GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS. */ +#ifndef USED_FOR_TARGET +#undef HAVE_LD_INDIRECT_EXTERN_ACCESS_SUPPORT +#endif + + /* Define if your PowerPC64 linker supports a large TOC. */ #ifndef USED_FOR_TARGET #undef HAVE_LD_LARGE_TOC diff --git a/gcc/config/i386/gnu-property.c b/gcc/config/i386/gnu-property.c index 4ba04403002..9fe8d00132e 100644 --- a/gcc/config/i386/gnu-property.c +++ b/gcc/config/i386/gnu-property.c @@ -24,37 +24,6 @@ along with GCC; see the file COPYING3. If not see #include "output.h" #include "linux-common.h" -static void -emit_gnu_property (unsigned int type, unsigned int data) -{ - int p2align = ptr_mode == SImode ? 2 : 3; - - switch_to_section (get_section (".note.gnu.property", - SECTION_NOTYPE, NULL)); - - ASM_OUTPUT_ALIGN (asm_out_file, p2align); - /* name length. */ - fprintf (asm_out_file, ASM_LONG "1f - 0f\n"); - /* data length. */ - fprintf (asm_out_file, ASM_LONG "4f - 1f\n"); - /* note type: NT_GNU_PROPERTY_TYPE_0. */ - fprintf (asm_out_file, ASM_LONG "5\n"); - fprintf (asm_out_file, "0:\n"); - /* vendor name: "GNU". */ - fprintf (asm_out_file, STRING_ASM_OP "\"GNU\"\n"); - fprintf (asm_out_file, "1:\n"); - ASM_OUTPUT_ALIGN (asm_out_file, p2align); - /* pr_type. */ - fprintf (asm_out_file, ASM_LONG "0x%x\n", type); - /* pr_datasz. */ - fprintf (asm_out_file, ASM_LONG "3f - 2f\n"); - fprintf (asm_out_file, "2:\n"); - fprintf (asm_out_file, ASM_LONG "0x%x\n", data); - fprintf (asm_out_file, "3:\n"); - ASM_OUTPUT_ALIGN (asm_out_file, p2align); - fprintf (asm_out_file, "4:\n"); -} - void file_end_indicate_exec_stack_and_gnu_property (void) { diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c index 7dee311051d..bd91c7cc7f8 100644 --- a/gcc/config/i386/i386.c +++ b/gcc/config/i386/i386.c @@ -24091,6 +24091,8 @@ ix86_run_selftests (void) #if !TARGET_MACHO && !TARGET_DLLIMPORT_DECL_ATTRIBUTES # undef TARGET_ASM_RELOC_RW_MASK # define TARGET_ASM_RELOC_RW_MASK ix86_reloc_rw_mask +# undef TARGET_ASM_EMIT_GNU_PROPERTY_NOTE +# define TARGET_ASM_EMIT_GNU_PROPERTY_NOTE emit_gnu_property_note #endif static bool ix86_libc_has_fast_function (int fcode ATTRIBUTE_UNUSED) diff --git a/gcc/configure b/gcc/configure index a15f8b47202..597b32b2959 100755 --- a/gcc/configure +++ b/gcc/configure @@ -32333,6 +32333,32 @@ fi { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ld_bndplt_support" >&5 $as_echo "$ld_bndplt_support" >&6; } +# Check if linker supports GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS. +ld_indirect_extern_access=0 +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking linker with GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS" >&5 +$as_echo_n "checking linker with GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS... " >&6; } +if test x"$ld_is_gold" = xno; then + if test $in_tree_ld = yes ; then + if test "$gcc_cv_gld_major_version" -eq 2 -a "$gcc_cv_gld_minor_version" -ge 38 -o "$gcc_cv_gld_major_version" -gt 2; then + ld_indirect_extern_access=1 + fi + elif test x$gcc_cv_ld != x; then + # --max-cache-size=SIZE and GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS + # were added to GNU linker within a day. Check --max-cache-size=SIZE + # for GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS support. + if $gcc_cv_ld --help 2>&1 | grep -- '--max-cache-size=SIZE' > /dev/null; then + ld_indirect_extern_access=1 + fi + fi +fi + +cat >>confdefs.h <<_ACEOF +#define HAVE_LD_INDIRECT_EXTERN_ACCESS_SUPPORT $ld_indirect_extern_access +_ACEOF + +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ld_indirect_extern_access" >&5 +$as_echo "$ld_indirect_extern_access" >&6; } + # Check linker supports '--push-state'/'--pop-state' ld_pushpopstate_support=no { $as_echo "$as_me:${as_lineno-$LINENO}: checking linker --push-state/--pop-state options" >&5 diff --git a/gcc/configure.ac b/gcc/configure.ac index 26da07325e7..2058b126107 100644 --- a/gcc/configure.ac +++ b/gcc/configure.ac @@ -7575,6 +7575,28 @@ if test x"$ld_bndplt_support" = xyes; then fi AC_MSG_RESULT($ld_bndplt_support) +# Check if linker supports GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS. +ld_indirect_extern_access=0 +AC_MSG_CHECKING(linker with GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS) +if test x"$ld_is_gold" = xno; then + if test $in_tree_ld = yes ; then + if test "$gcc_cv_gld_major_version" -eq 2 -a "$gcc_cv_gld_minor_version" -ge 38 -o "$gcc_cv_gld_major_version" -gt 2; then + ld_indirect_extern_access=1 + fi + elif test x$gcc_cv_ld != x; then + # --max-cache-size=SIZE and GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS + # were added to GNU linker within a day. Check --max-cache-size=SIZE + # for GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS support. + if $gcc_cv_ld --help 2>&1 | grep -- '--max-cache-size=SIZE' > /dev/null; then + ld_indirect_extern_access=1 + fi + fi +fi +AC_DEFINE_UNQUOTED(HAVE_LD_INDIRECT_EXTERN_ACCESS_SUPPORT, + $ld_indirect_extern_access, + [Define to 1 if your linker supports GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS.]) +AC_MSG_RESULT($ld_indirect_extern_access) + # Check linker supports '--push-state'/'--pop-state' ld_pushpopstate_support=no AC_MSG_CHECKING(linker --push-state/--pop-state options) diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi index 2a41ae5fba1..5b1f5c135b0 100644 --- a/gcc/doc/tm.texi +++ b/gcc/doc/tm.texi @@ -8073,6 +8073,11 @@ Output to @code{asm_out_file} any text which the assembler expects to find at the end of a file. The default is to output nothing. @end deftypefn +@deftypefn {Target Hook} void TARGET_ASM_EMIT_GNU_PROPERTY_NOTE (void) +Output a GNU property note to @code{asm_out_file}. The default is to +output nothing. +@end deftypefn + @deftypefun void file_end_indicate_exec_stack () Some systems use a common convention, the @samp{.note.GNU-stack} special section, to indicate whether or not an object file relies on diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in index f881cdabe9e..7091e02ca81 100644 --- a/gcc/doc/tm.texi.in +++ b/gcc/doc/tm.texi.in @@ -5050,6 +5050,8 @@ This describes the overall framework of an assembly file. @hook TARGET_ASM_FILE_END +@hook TARGET_ASM_EMIT_GNU_PROPERTY_NOTE + @deftypefun void file_end_indicate_exec_stack () Some systems use a common convention, the @samp{.note.GNU-stack} special section, to indicate whether or not an object file relies on diff --git a/gcc/output.h b/gcc/output.h index 73ca4545f4f..f9cbf7cab37 100644 --- a/gcc/output.h +++ b/gcc/output.h @@ -607,6 +607,8 @@ extern void default_asm_declare_constant_name (FILE *, const char *, extern void default_file_start (void); extern void file_end_indicate_exec_stack (void); extern void file_end_indicate_split_stack (void); +extern void emit_gnu_property (unsigned int, unsigned int); +extern void emit_gnu_property_note (void); extern void default_elf_asm_output_external (FILE *file, tree, const char *); diff --git a/gcc/target.def b/gcc/target.def index c009671c583..31e8bc0ab97 100644 --- a/gcc/target.def +++ b/gcc/target.def @@ -715,6 +715,14 @@ to find at the end of a file. The default is to output nothing.", void, (void), hook_void_void) +/* Output a GNU property note. */ +DEFHOOK +(emit_gnu_property_note, + "Output a GNU property note to @code{asm_out_file}. The default is to\n\ +output nothing.", + void, (void), + hook_void_void) + /* Output any boilerplate text needed at the beginning of an LTO output stream. */ DEFHOOK diff --git a/gcc/toplev.c b/gcc/toplev.c index 43f1f7d345e..a5c848cef22 100644 --- a/gcc/toplev.c +++ b/gcc/toplev.c @@ -586,6 +586,9 @@ compile_file (void) /* Invoke registered plugin callbacks. */ invoke_plugin_callbacks (PLUGIN_FINISH_UNIT, NULL); + /* Output a GNU property note. */ + targetm.asm_out.emit_gnu_property_note (); + /* This must be at the end. Some target ports emit end of file directives into the assembly file here, and hence we cannot output anything to the assembly file after this point. */ diff --git a/gcc/varasm.c b/gcc/varasm.c index 53cf6dea3f3..b0850864534 100644 --- a/gcc/varasm.c +++ b/gcc/varasm.c @@ -7729,6 +7729,53 @@ default_file_start (void) } } +/* Emit one GNU property of TYPE and DATA. */ + +void +emit_gnu_property (unsigned int type, unsigned int data) +{ + int p2align = ptr_mode == SImode ? 2 : 3; + + switch_to_section (get_section (".note.gnu.property", + SECTION_NOTYPE, NULL)); + + ASM_OUTPUT_ALIGN (asm_out_file, p2align); + /* name length. */ + fprintf (asm_out_file, ASM_LONG "1f - 0f\n"); + /* data length. */ + fprintf (asm_out_file, ASM_LONG "4f - 1f\n"); + /* note type: NT_GNU_PROPERTY_TYPE_0. */ + fprintf (asm_out_file, ASM_LONG "5\n"); + fprintf (asm_out_file, "0:\n"); + /* vendor name: "GNU". */ + fprintf (asm_out_file, STRING_ASM_OP "\"GNU\"\n"); + fprintf (asm_out_file, "1:\n"); + ASM_OUTPUT_ALIGN (asm_out_file, p2align); + /* pr_type. */ + fprintf (asm_out_file, ASM_LONG "0x%x\n", type); + /* pr_datasz. */ + fprintf (asm_out_file, ASM_LONG "3f - 2f\n"); + fprintf (asm_out_file, "2:\n"); + fprintf (asm_out_file, ASM_LONG "0x%x\n", data); + fprintf (asm_out_file, "3:\n"); + ASM_OUTPUT_ALIGN (asm_out_file, p2align); + fprintf (asm_out_file, "4:\n"); +} + +/* This is a generic routine for TARGET_ASM_EMIT_GNU_PROPERTY_NOTE to + emit a NT_GNU_PROPERTY_TYPE_0 note. This is primarily a GNU extension + to ELF but could be used on other targets. */ + +void +emit_gnu_property_note (void) +{ + if (HAVE_LD_INDIRECT_EXTERN_ACCESS_SUPPORT + && !flag_direct_extern_access) + /* Emite a GNU_PROPERTY_1_NEEDED note with + GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS. */ + emit_gnu_property (0xb0008000, (1U << 0)); +} + /* This is a generic routine suitable for use as TARGET_ASM_FILE_END which emits a special section directive used to indicate whether or not this object file needs an executable stack. This is primarily -- 2.31.1