On Wed, 01 May 2019 16:28:31 -0400 Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S > index d309f30cf7af..50bbf4035baf 100644 > --- a/arch/x86/entry/entry_32.S > +++ b/arch/x86/entry/entry_32.S > @@ -1478,6 +1478,17 @@ ENTRY(int3) > ASM_CLAC > pushl $-1 # mark this as an int > > +#ifdef CONFIG_VM86 > + testl $X86_EFLAGS_VM, PT_EFLAGS(%esp) > + jnz .Lfrom_usermode_no_gap > +#endif > + testl $SEGMENT_RPL_MASK, PT_CS(%esp) > + jnz .Lfrom_usermode_no_gap > + .rept 6 > + pushl 5*4(%esp) > + .endr > +.Lfrom_usermode_no_gap: > + > SAVE_ALL switch_stacks=1 > ENCODE_FRAME_POINTER > TRACE_IRQS_OFF This failed to work on 32 bit at all (crashed and burned badly - triple fault!). Looking at it I found one issue. This code is done before the regs are saved, and PT_EFLAGS(%esp) and PT_CS(%esp) expect %esp to contain them. I applied this patch against this but it didn't totally fix the problems. It still constantly crashes (although, with this update I can put in some printks to get some ideas). I haven't spent too much time on it, but it looks like there's an issue with the entry-stack that int3 switches to. I'm not sure its handling the copy well. -- Steve diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index 50bbf4035baf..4f427285e421 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -1479,10 +1479,10 @@ ENTRY(int3) pushl $-1 # mark this as an int #ifdef CONFIG_VM86 - testl $X86_EFLAGS_VM, PT_EFLAGS(%esp) + testl $X86_EFLAGS_VM, PT_EFLAGS-PT_ORIG_EAX(%esp) jnz .Lfrom_usermode_no_gap #endif - testl $SEGMENT_RPL_MASK, PT_CS(%esp) + testl $SEGMENT_RPL_MASK, PT_CS-PT_ORIG_EAX(%esp) jnz .Lfrom_usermode_no_gap .rept 6 pushl 5*4(%esp)
