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[PATCH v12 12/21] x86/xen: Add xen_cpuid() and xen_setup_gdt() to stacktool whitelists

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  [PATCH v12 12/21] x86/xen: Add xen_cpuid() and xen_setup_gdt() to stacktool whitelists Josh Poimboeuf <jpoimboe@redhat.com> - 2015-09-09 15:30 +0200
    Re: [PATCH v12 12/21] x86/xen: Add xen_cpuid() and xen_setup_gdt()  to stacktool whitelists David Vrabel <david.vrabel@citrix.com> - 2015-09-09 15:40 +0200

#1221433 — [PATCH v12 12/21] x86/xen: Add xen_cpuid() and xen_setup_gdt() to stacktool whitelists

stacktool reports the following false positive warnings:

  stacktool: arch/x86/xen/enlighten.o: xen_cpuid()+0x41: can't find jump dest instruction at .text+0x108
  stacktool: 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 stacktool doesn't know how to
decode.

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

Add both functions to the stacktool whitelist.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
---
 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..6cc682d 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/stacktool.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;
-
 }
+STACKTOOL_IGNORE_FUNC(xen_cpuid);
 
 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;
 }
+STACKTOOL_IGNORE_FUNC(xen_setup_gdt);
 
 #ifdef CONFIG_XEN_PVH
 /*
-- 
2.4.3

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#1221453 — Re: [PATCH v12 12/21] x86/xen: Add xen_cpuid() and xen_setup_gdt() to stacktool whitelists

On 09/09/15 14:21, Josh Poimboeuf wrote:
> stacktool reports the following false positive warnings:
> 
>   stacktool: arch/x86/xen/enlighten.o: xen_cpuid()+0x41: can't find jump dest instruction at .text+0x108
>   stacktool: 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 stacktool doesn't know how to
> decode.
> 
> The second warning is due to xen_setup_gdt()'s use of an lret
> instruction, which stacktool normally doesn't allow in callable
> functions.  But this seems to be a valid use of the instruction.
> 
> Add both functions to the stacktool whitelist.

Reviewed-by: David Vrabel <david.vrabel@citrix.com>

David
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