From: Ed Reed <ed.reed@aesec.com>
To: linux-assembly@vger.kernel.org
Subject: Question about entry.S RESTORE_REGS macro
Date: Mon, 25 Sep 2006 12:26:38 -0400 [thread overview]
Message-ID: <4518033E.7080903@aesec.com> (raw)
I'm looking at the entry / exit routines to the kernel in
arch/i386/kernel/entry.S, and at the entry conditions for
ret_from_fork() that is also defined there....
And looking at the assembler macro defined at the top of the file,
RESTORE_REGS, I'm trying to figure out what the ELF section stuff is
doing there - have you a clue, or a pointer you give me as to whom to
ask? I don't THINK it's relevant to my current efforts, but I'd like to
understand what's going on.
code:
#define SAVE_ALL \
cld; \
pushl %es; \
pushl %ds; \
pushl %eax; \
pushl %ebp; \
pushl %edi; \
pushl %esi; \
pushl %edx; \
pushl %ecx; \
pushl %ebx; \
movl $(__USER_DS), %edx; \
movl %edx, %ds; \
movl %edx, %es;
#define RESTORE_INT_REGS \
popl %ebx; \
popl %ecx; \
popl %edx; \
popl %esi; \
popl %edi; \
popl %ebp; \
popl %eax
#define RESTORE_REGS \
RESTORE_INT_REGS; \
1: popl %ds; \
2: popl %es; \
.section .fixup,"ax"; \
3: movl $0,(%esp); \
jmp 1b; \
4: movl $0,(%esp); \
jmp 2b; \
.previous; \
.section __ex_table,"a";\
.align 4; \
.long 1b,3b; \
.long 2b,4b; \
.previous
The SAVE_ALL and RESTORE_INT_REGS seem pretty straight forward, but in
RESTORE_REGS, are the two section entries and labels creating relocation
entries for the popl %ds and %es instructions?
Newbie question, I suppose, but that's the only think I can see that
would make sense, and don't know who else to ask.
reply other threads:[~2006-09-25 16:26 UTC|newest]
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