[PATCH v10 11/20] x86/xen: Add xen_cpuid() and xen_setup_gdt() to stackvalidate whitelists

From: Josh Poimboeuf
Date: Thu Aug 13 2015 - 23:14:57 EST

stackvalidate reports the following false positive warnings:

stackvalidate: arch/x86/xen/enlighten.o: xen_cpuid()+0x41: can't find jump dest instruction at .text+0x108
stackvalidate: arch/x86/xen/enlighten.o: xen_setup_gdt.constprop.23()+0x2e: kernel entry/exit from callable instruction

The first warning is due to xen_cpuid()'s use of XEN_EMULATE_PREFIX to
insert some fake instructions which stackvalidate doesn't know how to

The second warning is due to xen_setup_gdt()'s use of an lret
instruction, which stackvalidate normally doesn't allow in callable
functions. But this seems to be a valid use of the instruction.

Add both functions to the stackvalidate whitelist.

Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: David Vrabel <david.vrabel@xxxxxxxxxx>
arch/x86/xen/enlighten.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index d9cfa45..4ca89ac 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -32,6 +32,7 @@
#include <linux/gfp.h>
#include <linux/memblock.h>
#include <linux/edd.h>
+#include <linux/stackvalidate.h>

#include <xen/xen.h>
#include <xen/events.h>
@@ -345,8 +346,8 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx,
*cx &= maskecx;
*cx |= setecx;
*dx &= maskedx;

static bool __init xen_check_mwait(void)
@@ -1443,6 +1444,7 @@ static void __ref xen_setup_gdt(int cpu)
pv_cpu_ops.write_gdt_entry = xen_write_gdt_entry;
pv_cpu_ops.load_gdt = xen_load_gdt;


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