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.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>

diff --git a/sysdeps/aarch64/Makefile b/sysdeps/aarch64/Makefile
index 7183895d04ea8d42234683e184e4a68384f3405f..17fb1c5b727dda05b857e9b0a79e4c481e9cc889 100644 (file)
--- 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 b40050a9817873f445ba4b0ba7205f8650f0c596..fe120bb507d32cecf81a3a6b31892e83ddb73d71 100644 (file)
--- 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 (file)
index 0000000..a3a57bd
--- /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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <sysdep.h>
+
+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)