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x86: only enable interrupts when kernel state has been set up 

The sysenter path tries to enable interrupts immediately.  Unfortunately
this doesn't work in a paravirt environment, because not enough kernel
state has been set up at that point (namely, pointing %fs to the kernel
percpu data segment).  To fix this, defer ENABLE_INTERRUPTS until after
the kernel state has been set up.

Unfortunately this means that we're running with interrupts disabled
for a while without calling the IRQ tracing code, but that can't be
called without setting up %fs either.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Jeremy Fitzhardinge 2008-03-24 16:43:21 -07:00 committed by Ingo Molnar
parent 687c805409
commit d93c870bad
1 changed files with 10 additions and 9 deletions
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19
arch/x86/kernel/entry_32.S
View File

@ -291,10 +291,10 @@ ENTRY(ia32_sysenter_target)
movl TSS_sysenter_sp0(%esp),%esp
sysenter_past_esp:
/*
* No need to follow this irqs on/off section: the syscall
* disabled irqs and here we enable it straight after entry:
* Interrupts are disabled here, but we can't trace it until
* enough kernel state to call TRACE_IRQS_OFF can be called - but
* we immediately enable interrupts at that point anyway.
*/
ENABLE_INTERRUPTS(CLBR_NONE)
pushl $(__USER_DS)
CFI_ADJUST_CFA_OFFSET 4
/*CFI_REL_OFFSET ss, 0*/
@ -302,6 +302,7 @@ sysenter_past_esp:
CFI_ADJUST_CFA_OFFSET 4
CFI_REL_OFFSET esp, 0
pushfl
orl $X86_EFLAGS_IF, (%esp)
CFI_ADJUST_CFA_OFFSET 4
pushl $(__USER_CS)
CFI_ADJUST_CFA_OFFSET 4
@ -315,6 +316,11 @@ sysenter_past_esp:
CFI_ADJUST_CFA_OFFSET 4
CFI_REL_OFFSET eip, 0
pushl %eax
CFI_ADJUST_CFA_OFFSET 4
SAVE_ALL
ENABLE_INTERRUPTS(CLBR_NONE)
/*
* Load the potential sixth argument from user stack.
* Careful about security.
@ -322,14 +328,12 @@ sysenter_past_esp:
cmpl $__PAGE_OFFSET-3,%ebp
jae syscall_fault
1: movl (%ebp),%ebp
movl %ebp,PT_EBP(%esp)
.section __ex_table,"a"
.align 4
.long 1b,syscall_fault
.previous
pushl %eax
CFI_ADJUST_CFA_OFFSET 4
SAVE_ALL
GET_THREAD_INFO(%ebp)
/* Note, _TIF_SECCOMP is bit number 8, and so it needs testw and not testb */
@ -543,9 +547,6 @@ END(syscall_exit_work)
RING0_INT_FRAME # can't unwind into user space anyway
syscall_fault:
pushl %eax # save orig_eax
CFI_ADJUST_CFA_OFFSET 4
SAVE_ALL
GET_THREAD_INFO(%ebp)
movl $-EFAULT,PT_EAX(%esp)
jmp resume_userspace