um: Fix check for _xstate for older hosts
Commit 0a987645672e ("um: Allow building and running on older
hosts") attempted to check for PTRACE_{GET,SET}REGSET under the premise
that these ptrace(2) parameters were directly linked with the presence
of the _xstate structure.
After Richard's commit 61e8d462457f ("um: Correctly check for
PTRACE_GETRESET/SETREGSET") which properly included linux/ptrace.h
instead of asm/ptrace.h, we could get into the original build failure
that I reported:
arch/x86/um/user-offsets.c: In function 'foo':
arch/x86/um/user-offsets.c:54: error: invalid application of 'sizeof' to
incomplete type 'struct _xstate'
On this particular host, we do have PTRACE_GETREGSET and
PTRACE_SETREGSET defined in linux/ptrace.h, but not the structure
_xstate that should be pulled from the following include chain: signal.h
-> bits/sigcontext.h.
Correctly fix this by checking for FP_XSTATE_MAGIC1 which is the correct
way to see if struct _xstate is available or not on the host.
Fixes: 61e8d462457f ("um: Correctly check for PTRACE_GETRESET/SETREGSET")
Fixes: 0a987645672e ("um: Allow building and running on older hosts")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
diff --git a/arch/x86/um/user-offsets.c b/arch/x86/um/user-offsets.c
index ae4cd58..02250b2 100644
--- a/arch/x86/um/user-offsets.c
+++ b/arch/x86/um/user-offsets.c
@@ -50,7 +50,7 @@
DEFINE(HOST_GS, GS);
DEFINE(HOST_ORIG_AX, ORIG_EAX);
#else
-#if defined(PTRACE_GETREGSET) && defined(PTRACE_SETREGSET)
+#ifdef FP_XSTATE_MAGIC1
DEFINE(HOST_FP_SIZE, sizeof(struct _xstate) / sizeof(unsigned long));
#else
DEFINE(HOST_FP_SIZE, sizeof(struct _fpstate) / sizeof(unsigned long));