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[RFC PATCH 07/23] hurd: Pass the data pointer to _hurd_stack_setup expli
From: |
Sergey Bugaev |
Subject: |
[RFC PATCH 07/23] hurd: Pass the data pointer to _hurd_stack_setup explicitly |
Date: |
Wed, 3 Jan 2024 20:14:40 +0300 |
Instead of relying on the stack frame layout to figure out where the stack
pointer was prior to the _hurd_stack_setup () call, just pass the pointer
as an argument explicitly. This is less brittle and much more portable.
Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
---
sysdeps/mach/hurd/i386/static-start.S | 3 +++
sysdeps/mach/hurd/x86/init-first.c | 16 +++++++---------
sysdeps/mach/hurd/x86_64/static-start.S | 1 +
3 files changed, 11 insertions(+), 9 deletions(-)
diff --git a/sysdeps/mach/hurd/i386/static-start.S
b/sysdeps/mach/hurd/i386/static-start.S
index d83505b2..3ffcb47d 100644
--- a/sysdeps/mach/hurd/i386/static-start.S
+++ b/sysdeps/mach/hurd/i386/static-start.S
@@ -19,7 +19,10 @@
.text
.globl _start
_start:
+ pushl %esp
call _hurd_stack_setup
+ /* No need to "addl %4, %esp", since _hurd_stack_setup
+ * returns with an already adjusted stack pointer. */
xorl %edx, %edx
jmp _start1
diff --git a/sysdeps/mach/hurd/x86/init-first.c
b/sysdeps/mach/hurd/x86/init-first.c
index bb051418..6f71d71b 100644
--- a/sysdeps/mach/hurd/x86/init-first.c
+++ b/sysdeps/mach/hurd/x86/init-first.c
@@ -197,7 +197,7 @@ strong_alias (posixland_init, __libc_init_first);
which should not exist at all. */
void
inhibit_stack_protector
-_hurd_stack_setup (void)
+_hurd_stack_setup (void **argptr)
{
/* This is the very first C code that runs in a statically linked
executable -- calling this function is the first thing that _start in
@@ -206,14 +206,12 @@ _hurd_stack_setup (void)
_start1 expects the arguments, environment, and a Hurd data block to be
located at the top of the stack. The data may already be located there,
- or we may need to receive it from the exec server. */
- void *caller = __builtin_extract_return_addr (__builtin_return_address (0));
- /* If the arguments and environment are already located on the stack, this is
- where they are, just above our call frame. Note that this may not be a
- valid pointer in case we're supposed to receive the arguments from the
exec
- server, so we can not dereference it yet. */
- void **p = (void **) __builtin_frame_address (0) + 2;
+ or we may need to receive it from the exec server. If the data is located
+ on the stack (just above our call frame), argptr points to it. Note that
+ this may not be a valid pointer in case we're supposed to receive the
+ arguments from the exec server, so we can not dereference it yet. */
+ void *caller = __builtin_extract_return_addr (__builtin_return_address (0));
/* Init the essential things. */
first_init ();
@@ -245,7 +243,7 @@ _hurd_stack_setup (void)
the stack pointer to the data (which is somewhere on the current stack
anyway). This way, _start1 find the data on the top of the stack, just as
it expects to. */
- _hurd_startup (p, &doinit);
+ _hurd_startup (argptr, &doinit);
__builtin_unreachable ();
}
#endif
diff --git a/sysdeps/mach/hurd/x86_64/static-start.S
b/sysdeps/mach/hurd/x86_64/static-start.S
index 9b9db937..0ec00905 100644
--- a/sysdeps/mach/hurd/x86_64/static-start.S
+++ b/sysdeps/mach/hurd/x86_64/static-start.S
@@ -25,6 +25,7 @@ _start:
leaq __strlen_sse2(%rip), %rax
movq %rax, strlen@GOTPCREL(%rip)
+ movq %rsp, %rdi
call _hurd_stack_setup
xorq %rdx, %rdx
jmp _start1
--
2.43.0
- Re: [PATCH 01/23] hurd: Add some missing includes, (continued)
Re: [PATCH 01/23] hurd: Add some missing includes, Samuel Thibault, 2024/01/03
[PATCH 02/23] hurd: Declare _hurd_intr_rpc_msg* with protected visibility, Sergey Bugaev, 2024/01/03
[PATCH 04/23] mach: Drop some unnecessary vm_param.h includes, Sergey Bugaev, 2024/01/03
[RFC PATCH 03/23] Allow glibc to be compiled without EXEC_PAGESIZE, Sergey Bugaev, 2024/01/03
[RFC PATCH 08/23] hurd: Drop x86-specific assembly from init-first.c, Sergey Bugaev, 2024/01/03
[RFC PATCH 07/23] hurd: Pass the data pointer to _hurd_stack_setup explicitly,
Sergey Bugaev <=
[PATCH 06/23] mach: Drop SNARF_ARGS macro, Sergey Bugaev, 2024/01/03
[RFC PATCH 09/23] hurd: Make init-first.c no longer x86-specific, Sergey Bugaev, 2024/01/03
[RFC PATCH 10/23] hurd: Only init early static TLS if it's used to store stack or pointer guards, Sergey Bugaev, 2024/01/03
[RFC PATCH 11/23] hurd: Initializy _dl_pagesize early in static builds, Sergey Bugaev, 2024/01/03
[RFC PATCH 12/23] aarch64: Make cpu-features definitions not Linux-specific, Sergey Bugaev, 2024/01/03