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x86/uaccess, xen: Suppress SMAP warnings 

drivers/xen/privcmd.o: warning: objtool: privcmd_ioctl()+0x1414: call to hypercall_page() with UACCESS enabled

Some Xen hypercalls allow parameter buffers in user land, so they need
to set AC=1. Avoid the warning for those cases.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: andrew.cooper3@citrix.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2019-03-06 19:09:08 +01:00 committed by Ingo Molnar
parent ff05ab2305
commit 4fc0f0e947
1 changed files with 20 additions and 4 deletions
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24
arch/x86/include/asm/xen/hypercall.h
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@ -214,6 +214,22 @@ xen_single_call(unsigned int call,
return (long)__res;
}
static __always_inline void __xen_stac(void)
{
/*
* Suppress objtool seeing the STAC/CLAC and getting confused about it
* calling random code with AC=1.
*/
asm volatile(ANNOTATE_IGNORE_ALTERNATIVE
ASM_STAC ::: "memory", "flags");
}
static __always_inline void __xen_clac(void)
{
asm volatile(ANNOTATE_IGNORE_ALTERNATIVE
ASM_CLAC ::: "memory", "flags");
}
static inline long
privcmd_call(unsigned int call,
unsigned long a1, unsigned long a2,
@ -222,9 +238,9 @@ privcmd_call(unsigned int call,
{
long res;
stac();
__xen_stac();
res = xen_single_call(call, a1, a2, a3, a4, a5);
clac();
__xen_clac();
return res;
}
@ -421,9 +437,9 @@ HYPERVISOR_dm_op(
domid_t dom, unsigned int nr_bufs, struct xen_dm_op_buf *bufs)
{
int ret;
stac();
__xen_stac();
ret = _hypercall3(int, dm_op, dom, nr_bufs, bufs);
clac();
__xen_clac();
return ret;
}