um: Fix check for _xstate for older hosts

ffainelli · richardweinberger · commit 2fb44600fe78 · 2017-08-24T21:52:28.000+02:00
Commit 0a98764 ("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 61e8d46 ("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: 61e8d46 ("um: Correctly check for PTRACE_GETRESET/SETREGSET") Fixes: 0a98764 ("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
@@ -50,7 +50,7 @@ void foo(void)
 	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));
