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[RFC PATCH 5/9] hurd: Simplify init-first.c a bit
From: |
Sergey Bugaev |
Subject: |
[RFC PATCH 5/9] hurd: Simplify init-first.c a bit |
Date: |
Sat, 18 Feb 2023 23:37:13 +0300 |
And make it a bit more 64-bit ready. This is in preparation to moving this
file into x86/
Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
---
sysdeps/mach/hurd/i386/init-first.c | 23 +++++++----------------
1 file changed, 7 insertions(+), 16 deletions(-)
diff --git a/sysdeps/mach/hurd/i386/init-first.c
b/sysdeps/mach/hurd/i386/init-first.c
index 94c94651..a558da16 100644
--- a/sysdeps/mach/hurd/i386/init-first.c
+++ b/sysdeps/mach/hurd/i386/init-first.c
@@ -195,7 +195,7 @@ init (int *data)
/* Call `init1' (above) with the user code as the return address, and the
argument data immediately above that on the stack. */
- int usercode;
+ void *usercode, **ret_address;
void call_init1 (void);
@@ -206,10 +206,11 @@ init (int *data)
recognize that this read operation may alias the following write
operation, and thus is free to reorder the two, clobbering the
original return address. */
- usercode = *((int *) __builtin_frame_address (0) + 1);
+ ret_address = (void **) __builtin_frame_address (0) + 1;
+ usercode = *ret_address;
/* GCC 4.4.6 also wants us to force loading USERCODE already here. */
asm volatile ("# %0" : : "X" (usercode));
- *((void **) __builtin_frame_address (0) + 1) = &call_init1;
+ *ret_address = &call_init1;
/* Force USERCODE into %eax and &init1 into %ecx, which are not
restored by function return. */
asm volatile ("# a %0 c %1" : : "a" (usercode), "c" (&init1));
@@ -223,19 +224,9 @@ init (int *data)
/* The return address of `init' above, was redirected to here, so at
this point our stack is unwound and callers' registers restored.
Only %ecx and %eax are call-clobbered and thus still have the
- values we set just above. Fetch from there the new stack pointer
- we will run on, and jmp to the run-time address of `init1'; when it
- returns, it will run the user code with the argument data at the
- top of the stack. */
-asm ("switch_stacks:\n"
- " movl %eax, %esp\n"
- " jmp *%ecx");
-
-/* As in the stack-switching case, at this point our stack is unwound
- and callers' registers restored, and only %ecx and %eax communicate
- values from the lines above. In this case we have stashed in %eax
- the user code return address. Push it on the top of the stack so
- it acts as init1's return address, and then jump there. */
+ values we set just above. We have stashed in %eax the user code
+ return address. Push it on the top of the stack so it acts as
+ init1's return address, and then jump there. */
asm ("call_init1:\n"
" push %eax\n"
" jmp *%ecx\n");
--
2.39.2
- [RFC PATCH 0/9] More x86_64-gnu glibc work, Sergey Bugaev, 2023/02/18
- [RFC PATCH 1/9] hurd: Move thread state manipulation into _hurd_tls_new (), Sergey Bugaev, 2023/02/18
- [RFC PATCH 2/9] hurd: Use proper integer types, Sergey Bugaev, 2023/02/18
- [RFC PATCH 3/9] hurd: Fix xattr function return type, Sergey Bugaev, 2023/02/18
- [RFC PATCH 5/9] hurd: Simplify init-first.c a bit,
Sergey Bugaev <=
- [RFC PATCH 4/9] hurd: Make timer_t pointer-sized, Sergey Bugaev, 2023/02/18
- [RFC PATCH 6/9] mach: Use PAGE_SIZE, Sergey Bugaev, 2023/02/18
- [RFC PATCH 7/9] hurd: Generalize init-first.c to support x86_64, Sergey Bugaev, 2023/02/18