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Being on a kernel stack doesn't mean we didn't come from userland: we now

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no longer pop %fs from the iframe in that case, too.
When we restore a custom stack, however, we'll now pop %fs from the iframe
as such strange threads may even do their own business with it.
Added some comments.


git-svn-id: file:///srv/svn/repos/haiku/trunk/current@9369 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Axel Dörfler 2004-10-15 15:50:41 +00:00
parent d296d770a3
commit 8593dcc214
1 changed files with 18 additions and 18 deletions
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36
src/kernel/core/arch/x86/arch_interrupts.S
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@ -93,17 +93,17 @@ int_bottom:
movl %eax,%ds
movl %eax,%es
movl %ss,%ebx
movl %esp,%esi
cmpl %eax,%ebx // check if we changed the stack
movl %esp,%esi // save the old stack pointer
cmpl %eax,%ebx // check if we changed the stack
jne custom_stack
kernel_stack:
call i386_handle_trap
pop %gs
pop %fs // kernel stacks don't care about TLS (which uses %fs)
addl $4, %esp // we skip %fs, as this contains the CPU dependent TLS segment
pop %es
pop %ds
popa
addl $16,%esp
addl $16,%esp // ignore the vector, error code, and original eax/edx values
iret
// custom stack -> copy registers to kernel stack and switch there
@ -112,23 +112,23 @@ int_bottom:
movl %eax,%es // the iframe is on the wrong stack
addl _interrupt_stack_offset,%edx
lss (%edx),%esp
movl %ebx,%ds
movl %ebx,%ds // point %ds to the user stack segment
subl $92,%esp
movl %esp,%edi
movl $21,%ecx
rep movsl
movl %esp,%edi // copy to the current stack
movl $21,%ecx // copy sizeof(iframe)
rep movsl // %esi still points to the old custom stack address
movl %eax,%ds
subl $84,%esi
movl %esi,(%edi) // save custom stack address
movl %ebx,4(%edi)
movl %esi,(%edi) // save custom stack address and segment *after* the
movl %ebx,4(%edi) // iframe structure on the stack
call i386_handle_trap
lss 84(%esp),%esp // reload custom stack address
pop %gs
addl $4, %esp // we skip %fs, as this contains the CPU dependent TLS segment
pop %fs // doesn't come from userland, doesn't need TLS, may have changed %fs
pop %es
pop %ds
popa
addl $16,%esp
addl $16,%esp // ignore the vector, error code, and original eax/edx values
iret
_interrupt_stack_offset:
@ -190,13 +190,13 @@ FUNCTION(i386_end_return_from_signal):
*/
FUNCTION(i386_restore_frame_from_syscall):
add $4, %esp // make the iframe our current stack position (we don't need the
// return address anymore, as we will use the one of the frame)
pop %gs // recreate the frame environment
addl $4, %esp // we skip %fs, as this contains the CPU dependent TLS segment
addl $4, %esp // make the iframe our current stack position (we don't need the
// return address anymore, as we will use the one of the frame)
pop %gs // recreate the frame environment
addl $4, %esp // we skip %fs, as this contains the CPU dependent TLS segment
pop %es
pop %ds
popa
addl $16,%esp // ignore the vector, error code, and original eax/edx values
// (which contain the syscall number and argument pointer)
addl $16,%esp // ignore the vector, error code, and original eax/edx values
// (which contain the syscall number and argument pointer)
iret