In a 32-bit SMP kernel, the stack canary is a percpu variable accessed as %fs:__stack_chk_guard. However, the ABI for PVH entry does not specify the %fs register state. It currently works because the initial %fs register is 0x10 for QEMU, which is the same as $PVH_DS_SEL. %However, for added safety, the percpu should be set up explicitly %before calling xen_prepare_pvh(), which accesses the stack canary. Signed-off-by: Hou Wenlong <houwenlong.hwl@xxxxxxxxxxxx> --- arch/x86/platform/pvh/head.S | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/platform/pvh/head.S b/arch/x86/platform/pvh/head.S index c4365a05ab83..cee4dadf5344 100644 --- a/arch/x86/platform/pvh/head.S +++ b/arch/x86/platform/pvh/head.S @@ -121,6 +121,10 @@ SYM_CODE_START_LOCAL(pvh_start_xen) ljmp $PVH_CS_SEL, $1f 1: + /* Set percpu for stack canary. */ + mov $PVH_DS_SEL,%eax + mov %eax, %fs + call xen_prepare_pvh mov $_pa(pvh_bootparams), %esi -- 2.31.1
