From: Jan Beulich Date: Fri, 9 Apr 2021 07:12:51 +0000 (+0200) Subject: x86: refine guest_mode() X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=dfcf494f96671a9d3ee2fed70250ef1eedc1c00e;p=people%2Fsstabellini%2Fxen-unstable.git%2F.git x86: refine guest_mode() The 2nd of the assertions as well as the macro's return value have been assuming we're on the primary stack. While for most IST exceptions we switch back to the main one when user mode was interrupted, for #DF we intentionally never do, and hence a #DF actually triggering on a user mode insn (which then is still a Xen bug) would in turn trigger this assertion, rather than cleanly logging state. Reported-by: Andrew Cooper Signed-off-by: Jan Beulich Reviewed-by: Roger Pau Monné --- diff --git a/xen/include/asm-x86/regs.h b/xen/include/asm-x86/regs.h index 8d984ea388..3fb94deedc 100644 --- a/xen/include/asm-x86/regs.h +++ b/xen/include/asm-x86/regs.h @@ -10,9 +10,10 @@ /* Frame pointer must point into current CPU stack. */ \ ASSERT(diff < STACK_SIZE); \ /* If not a guest frame, it must be a hypervisor frame. */ \ - ASSERT((diff == 0) || (r->cs == __HYPERVISOR_CS)); \ + if ( diff < PRIMARY_STACK_SIZE ) \ + ASSERT(!diff || ((r)->cs == __HYPERVISOR_CS)); \ /* Return TRUE if it's a guest frame. */ \ - (diff == 0); \ + !diff || ((r)->cs != __HYPERVISOR_CS); \ }) #define read_sreg(name) ({ \