What about this? It even generates shorter code in each branch, as
movl xx(%esp),%yy is 4 byte, while movl xx(%ebx),%yy is 3 byte opcode.
I also converted "movl %4(%edx),%edx; call *%edx" to "call *4(%edx)", 2 bytes
and one opcode shorter. I hope that it is also faster...
Appears to work...
Petr Vandrovec
vandrove@vc.cvut.cz
---lcall7 and lcall27 paths differ only in one constant. Let's use constant first, and execute common code after this.
entry.S | 47 ++++++++++++----------------------------------- 1 files changed, 12 insertions(+), 35 deletions(-)
--- linux-2.5.47-c849.dist/arch/i386/kernel/entry.S 2002-11-14 19:38:33.000000000 +0100 +++ linux-2.5.47-c849/arch/i386/kernel/entry.S 2002-11-14 20:53:26.000000000 +0100 @@ -130,12 +130,16 @@ # gates, which has to be cleaned up later.. pushl %eax SAVE_ALL - movl EIP(%esp), %eax # due to call gates, this is eflags, not eip.. - movl CS(%esp), %edx # this is eip.. - movl EFLAGS(%esp), %ecx # and this is cs.. - movl %eax,EFLAGS(%esp) # - movl %edx,EIP(%esp) # Now we move them to their "normal" places - movl %ecx,CS(%esp) # + movl %esp, %ebx + pushl %ebx + pushl $0x7 +do_lcall: + movl EIP(%ebx), %eax # due to call gates, this is eflags, not eip.. + movl CS(%ebx), %edx # this is eip.. + movl EFLAGS(%ebx), %ecx # and this is cs.. + movl %eax,EFLAGS(%ebx) # + movl %edx,EIP(%ebx) # Now we move them to their "normal" places + movl %ecx,CS(%ebx) # # # Call gates don't clear TF and NT in eflags like @@ -147,13 +151,9 @@ pushl %eax popfl - movl %esp, %ebx - pushl %ebx andl $-8192, %ebx # GET_THREAD_INFO movl TI_EXEC_DOMAIN(%ebx), %edx # Get the execution domain - movl 4(%edx), %edx # Get the lcall7 handler for the domain - pushl $0x7 - call *%edx + call *4(%edx) # Call the lcall7 handler for the domain addl $4, %esp popl %eax jmp resume_userspace @@ -163,33 +163,10 @@ # gates, which has to be cleaned up later.. pushl %eax SAVE_ALL - movl EIP(%esp), %eax # due to call gates, this is eflags, not eip.. - movl CS(%esp), %edx # this is eip.. - movl EFLAGS(%esp), %ecx # and this is cs.. - movl %eax,EFLAGS(%esp) # - movl %edx,EIP(%esp) # Now we move them to their "normal" places - movl %ecx,CS(%esp) # - - # - # Call gates don't clear TF and NT in eflags like - # traps do, so we need to do it ourselves. - # %eax already contains eflags (but it may have - # DF set, clear that also) - # - andl $~(DF_MASK | TF_MASK | NT_MASK),%eax - pushl %eax - popfl - movl %esp, %ebx pushl %ebx - andl $-8192, %ebx # GET_THREAD_INFO - movl TI_EXEC_DOMAIN(%ebx), %edx # Get the execution domain - movl 4(%edx), %edx # Get the lcall7 handler for the domain pushl $0x27 - call *%edx - addl $4, %esp - popl %eax - jmp resume_userspace + jmp do_lcall ENTRY(ret_from_fork) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/