From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1944) id 477893857347; Wed, 4 May 2022 06:03:14 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 477893857347 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Szabolcs Nagy To: glibc-cvs@sourceware.org Subject: [glibc/nsz/bug23293] aarch64: Move ld.so _start to separate file and drop _dl_skip_args X-Act-Checkin: glibc X-Git-Author: Szabolcs Nagy X-Git-Refname: refs/heads/nsz/bug23293 X-Git-Oldrev: 671e2f493e59ae35b68d5c72fc0f6865bf1d562b X-Git-Newrev: 04cfa0c448fe88a5fd9895b65c4b8f15de63cda3 Message-Id: <20220504060314.477893857347@sourceware.org> Date: Wed, 4 May 2022 06:03:14 +0000 (GMT) X-BeenThere: glibc-cvs@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Glibc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 04 May 2022 06:03:14 -0000 https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=04cfa0c448fe88a5fd9895b65c4b8f15de63cda3 commit 04cfa0c448fe88a5fd9895b65c4b8f15de63cda3 Author: Szabolcs Nagy Date: Thu Dec 30 17:08:36 2021 +0000 aarch64: Move ld.so _start to separate file and drop _dl_skip_args A separate asm file is easier to maintain than a macro that expands to inline asm. The RTLD_START macro is only needed now because _dl_start is local in rtld.c, but _start has to call it, if _dl_start was made hidden then it could be empty. _dl_skip_args is no longer needed. --- v4: - adjust commit message about _dl_skip_args. v3: - mention _dl_skip_args v2: - fix typo in commit message. Diff: --- sysdeps/aarch64/Makefile | 1 + sysdeps/aarch64/dl-machine.h | 77 ++------------------------------------------ sysdeps/aarch64/dl-start.S | 53 ++++++++++++++++++++++++++++++ 3 files changed, 56 insertions(+), 75 deletions(-) diff --git a/sysdeps/aarch64/Makefile b/sysdeps/aarch64/Makefile index 7183895d04..17fb1c5b72 100644 --- a/sysdeps/aarch64/Makefile +++ b/sysdeps/aarch64/Makefile @@ -33,6 +33,7 @@ tst-audit27-ENV = LD_AUDIT=$(objpfx)tst-auditmod27.so endif ifeq ($(subdir),elf) +sysdep-rtld-routines += dl-start sysdep-dl-routines += tlsdesc dl-tlsdesc gen-as-const-headers += dl-link.sym diff --git a/sysdeps/aarch64/dl-machine.h b/sysdeps/aarch64/dl-machine.h index b40050a981..fe120bb507 100644 --- a/sysdeps/aarch64/dl-machine.h +++ b/sysdeps/aarch64/dl-machine.h @@ -105,81 +105,8 @@ elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[], return lazy; } -/* Initial entry point for the dynamic linker. The C function - _dl_start is the real entry point, its return value is the user - program's entry point */ -#ifdef __LP64__ -# define RTLD_START RTLD_START_1 ("x", "3", "sp") -#else -# define RTLD_START RTLD_START_1 ("w", "2", "wsp") -#endif - - -#define RTLD_START_1(PTR, PTR_SIZE_LOG, PTR_SP) asm ("\ -.text \n\ -.globl _start \n\ -.type _start, %function \n\ -.globl _dl_start_user \n\ -.type _dl_start_user, %function \n\ -_start: \n\ - // bti c \n\ - hint 34 \n\ - mov " PTR "0, " PTR_SP " \n\ - bl _dl_start \n\ - // returns user entry point in x0 \n\ - mov x21, x0 \n\ -_dl_start_user: \n\ - // get the original arg count \n\ - ldr " PTR "1, [sp] \n\ - // get the argv address \n\ - add " PTR "2, " PTR_SP ", #(1<<" PTR_SIZE_LOG ") \n\ - // get _dl_skip_args to see if we were \n\ - // invoked as an executable \n\ - adrp x4, _dl_skip_args \n\ - ldr w4, [x4, #:lo12:_dl_skip_args] \n\ - // do we need to adjust argc/argv \n\ - cmp w4, 0 \n\ - beq .L_done_stack_adjust \n\ - // subtract _dl_skip_args from original arg count \n\ - sub " PTR "1, " PTR "1, " PTR "4 \n\ - // store adjusted argc back to stack \n\ - str " PTR "1, [sp] \n\ - // find the first unskipped argument \n\ - mov " PTR "3, " PTR "2 \n\ - add " PTR "4, " PTR "2, " PTR "4, lsl #" PTR_SIZE_LOG " \n\ - // shuffle argv down \n\ -1: ldr " PTR "5, [x4], #(1<<" PTR_SIZE_LOG ") \n\ - str " PTR "5, [x3], #(1<<" PTR_SIZE_LOG ") \n\ - cmp " PTR "5, #0 \n\ - bne 1b \n\ - // shuffle envp down \n\ -1: ldr " PTR "5, [x4], #(1<<" PTR_SIZE_LOG ") \n\ - str " PTR "5, [x3], #(1<<" PTR_SIZE_LOG ") \n\ - cmp " PTR "5, #0 \n\ - bne 1b \n\ - // shuffle auxv down \n\ -1: ldp " PTR "0, " PTR "5, [x4, #(2<<" PTR_SIZE_LOG ")]! \n\ - stp " PTR "0, " PTR "5, [x3], #(2<<" PTR_SIZE_LOG ") \n\ - cmp " PTR "0, #0 \n\ - bne 1b \n\ - // Update _dl_argv \n\ - adrp x3, __GI__dl_argv \n\ - str " PTR "2, [x3, #:lo12:__GI__dl_argv] \n\ -.L_done_stack_adjust: \n\ - // compute envp \n\ - add " PTR "3, " PTR "2, " PTR "1, lsl #" PTR_SIZE_LOG " \n\ - add " PTR "3, " PTR "3, #(1<<" PTR_SIZE_LOG ") \n\ - adrp x16, _rtld_local \n\ - add " PTR "16, " PTR "16, #:lo12:_rtld_local \n\ - ldr " PTR "0, [x16] \n\ - bl _dl_init \n\ - // load the finalizer function \n\ - adrp x0, _dl_fini \n\ - add " PTR "0, " PTR "0, #:lo12:_dl_fini \n\ - // jump to the user_s entry point \n\ - mov x16, x21 \n\ - br x16 \n\ -"); +/* In elf/rtld.c _dl_start should be global so dl-start.S can reference it. */ +#define RTLD_START asm (".globl _dl_start"); #define elf_machine_type_class(type) \ ((((type) == AARCH64_R(JUMP_SLOT) \ diff --git a/sysdeps/aarch64/dl-start.S b/sysdeps/aarch64/dl-start.S new file mode 100644 index 0000000000..a3a57bd5a1 --- /dev/null +++ b/sysdeps/aarch64/dl-start.S @@ -0,0 +1,53 @@ +/* ld.so _start code. + Copyright (C) 2022 Free Software Foundation, Inc. + + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#include + +ENTRY (_start) + /* Create an initial frame with 0 LR and FP */ + cfi_undefined (x30) + mov x29, #0 + mov x30, #0 + + mov x0, sp + PTR_ARG (0) + bl _dl_start + /* Returns user entry point in x0. */ + mov PTR_REG (21), PTR_REG (0) +.globl _dl_start_user +.type _dl_start_user, %function +_dl_start_user: + /* Get argc. */ + ldr PTR_REG (1), [sp] + /* Get argv. */ + add x2, sp, PTR_SIZE + /* Compute envp. */ + add PTR_REG (3), PTR_REG (2), PTR_REG (1), lsl PTR_LOG_SIZE + add PTR_REG (3), PTR_REG (3), PTR_SIZE + adrp x16, _rtld_local + add PTR_REG (16), PTR_REG (16), :lo12:_rtld_local + ldr PTR_REG (0), [x16] + bl _dl_init + /* Load the finalizer function. */ + adrp x0, _dl_fini + add PTR_REG (0), PTR_REG (0), :lo12:_dl_fini + /* Jump to the user's entry point. */ + mov x16, x21 + br x16 +END (_start)