diff mbox series

[16/17] x86_64: Remove _dl_skip_args usage

Message ID 20220526165003.705355-17-adhemerval.zanella@linaro.org
State Committed
Commit ec7bc492b6047529603bb7f59575b6551c73639e
Headers
Series Remove _dl_skip_args |

Checks

Context Check Description
dj/TryBot-apply_patch success Patch applied to master at the time it was sent

Commit Message

Adhemerval Zanella May 26, 2022, 4:50 p.m. UTC 
  Since ad43cac44a the generic code already shuffles the argv/envp/auxv
on the stack to remove the ld.so own arguments and thus _dl_skip_args
is always 0.   So there is no need to adjust the argc or argv.

Checked on x86_64-linux-gnu and i686-linux-gnu.
---
 sysdeps/x86_64/dl-machine.h     | 13 ++-----------
 sysdeps/x86_64/x32/dl-machine.h | 12 +-----------
 2 files changed, 3 insertions(+), 22 deletions(-)

Comments

H.J. Lu May 26, 2022, 8:52 p.m. UTC | #1 
On Thu, May 26, 2022 at 10:02 AM Adhemerval Zanella via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> Since ad43cac44a the generic code already shuffles the argv/envp/auxv
> on the stack to remove the ld.so own arguments and thus _dl_skip_args
> is always 0.   So there is no need to adjust the argc or argv.
>
> Checked on x86_64-linux-gnu and i686-linux-gnu.
> ---
>  sysdeps/x86_64/dl-machine.h     | 13 ++-----------
>  sysdeps/x86_64/x32/dl-machine.h | 12 +-----------
>  2 files changed, 3 insertions(+), 22 deletions(-)
>
> diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h
> index c70af7ab1e..e33ca2cc1a 100644
> --- a/sysdeps/x86_64/dl-machine.h
> +++ b/sysdeps/x86_64/dl-machine.h
> @@ -140,17 +140,8 @@ _start:\n\
>  _dl_start_user:\n\
>         # Save the user entry point address in %r12.\n\
>         movq %rax, %r12\n\
> -       # See if we were run as a command with the executable file\n\
> -       # name as an extra leading argument.\n\
> -       movl _dl_skip_args(%rip), %eax\n\
> -       # Pop the original argument count.\n\
> -       popq %rdx\n\
> -       # Adjust the stack pointer to skip _dl_skip_args words.\n\
> -       leaq (%rsp,%rax,8), %rsp\n\
> -       # Subtract _dl_skip_args from argc.\n\
> -       subl %eax, %edx\n\
> -       # Push argc back on the stack.\n\
> -       pushq %rdx\n\
> +       # Read the original argument count.\n\
> +       movq (%rsp), %rdx\n\
>         # Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)\n\
>         # argc -> rsi\n\
>         movq %rdx, %rsi\n\
> diff --git a/sysdeps/x86_64/x32/dl-machine.h b/sysdeps/x86_64/x32/dl-machine.h
> index 331374069e..681016c8d8 100644
> --- a/sysdeps/x86_64/x32/dl-machine.h
> +++ b/sysdeps/x86_64/x32/dl-machine.h
> @@ -45,18 +45,8 @@ _start:\n\
>  _dl_start_user:\n\
>         # Save the user entry point address in %r12.\n\
>         movl %eax, %r12d\n\
> -       # See if we were run as a command with the executable file\n\
> -       # name as an extra leading argument.\n\
> -       movl _dl_skip_args(%rip), %eax\n\
> -       # Pop the original argument count.\n\
> +       # Read the original argument count.\n\
>         movl (%rsp), %edx\n\
> -       # Adjust the stack pointer to skip _dl_skip_args words.\n\
> -       lea 4(%rsp,%rax,4), %esp\n\
> -       # Subtract _dl_skip_args from argc.\n\
> -       subl %eax, %edx\n\
> -       # Push argc back on the stack.\n\
> -       subl $4, %esp\n\
> -       movl %edx, (%rsp)\n\
>         # Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)\n\
>         # argc -> rsi\n\
>         movl %edx, %esi\n\
> --
> 2.34.1
>

LGTM.

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>

Thanks.
diff mbox series

Patch

diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h
index c70af7ab1e..e33ca2cc1a 100644
--- a/sysdeps/x86_64/dl-machine.h
+++ b/sysdeps/x86_64/dl-machine.h
@@ -140,17 +140,8 @@  _start:\n\
 _dl_start_user:\n\
 	# Save the user entry point address in %r12.\n\
 	movq %rax, %r12\n\
-	# See if we were run as a command with the executable file\n\
-	# name as an extra leading argument.\n\
-	movl _dl_skip_args(%rip), %eax\n\
-	# Pop the original argument count.\n\
-	popq %rdx\n\
-	# Adjust the stack pointer to skip _dl_skip_args words.\n\
-	leaq (%rsp,%rax,8), %rsp\n\
-	# Subtract _dl_skip_args from argc.\n\
-	subl %eax, %edx\n\
-	# Push argc back on the stack.\n\
-	pushq %rdx\n\
+	# Read the original argument count.\n\
+	movq (%rsp), %rdx\n\
 	# Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)\n\
 	# argc -> rsi\n\
 	movq %rdx, %rsi\n\
diff --git a/sysdeps/x86_64/x32/dl-machine.h b/sysdeps/x86_64/x32/dl-machine.h
index 331374069e..681016c8d8 100644
--- a/sysdeps/x86_64/x32/dl-machine.h
+++ b/sysdeps/x86_64/x32/dl-machine.h
@@ -45,18 +45,8 @@  _start:\n\
 _dl_start_user:\n\
 	# Save the user entry point address in %r12.\n\
 	movl %eax, %r12d\n\
-	# See if we were run as a command with the executable file\n\
-	# name as an extra leading argument.\n\
-	movl _dl_skip_args(%rip), %eax\n\
-	# Pop the original argument count.\n\
+	# Read the original argument count.\n\
 	movl (%rsp), %edx\n\
-	# Adjust the stack pointer to skip _dl_skip_args words.\n\
-	lea 4(%rsp,%rax,4), %esp\n\
-	# Subtract _dl_skip_args from argc.\n\
-	subl %eax, %edx\n\
-	# Push argc back on the stack.\n\
-	subl $4, %esp\n\
-	movl %edx, (%rsp)\n\
 	# Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)\n\
 	# argc -> rsi\n\
 	movl %edx, %esi\n\