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* [glibc] hurd: Pass the data pointer to _hurd_stack_setup explicitly
@ 2024-01-04 22:49 Samuel Thibault
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From: Samuel Thibault @ 2024-01-04 22:49 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=24b707c1665afae7eb302542ffa92d53aa577111
commit 24b707c1665afae7eb302542ffa92d53aa577111
Author: Sergey Bugaev <bugaevc@gmail.com>
Date: Wed Jan 3 20:14:40 2024 +0300
hurd: Pass the data pointer to _hurd_stack_setup explicitly
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>
Message-ID: <20240103171502.1358371-8-bugaevc@gmail.com>
Diff:
---
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 d83505b2bc..3ffcb47d90 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 bb05141899..6f71d71bf0 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 9b9db937bd..0ec00905a0 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
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