um: Use POSIX ucontext_t instead of struct ucontext

Krzysztof Mazur · richardweinberger · commit 4d1a535b8ec5 · 2018-02-19T19:38:51.000+01:00
glibc 2.26 removed the 'struct ucontext' to "improve" POSIX compliance
and break programs, including User Mode Linux. Fix User Mode Linux
by using POSIX ucontext_t.

This fixes:

arch/um/os-Linux/signal.c: In function 'hard_handler':
arch/um/os-Linux/signal.c:163:22: error: dereferencing pointer to incomplete type 'struct ucontext'
  mcontext_t *mc = &amp;uc-&gt;uc_mcontext;
arch/x86/um/stub_segv.c: In function 'stub_segv_handler':
arch/x86/um/stub_segv.c:16:13: error: dereferencing pointer to incomplete type 'struct ucontext'
          &amp;uc-&gt;uc_mcontext);

Cc: stable@vger.kernel.org
Signed-off-by: Krzysztof Mazur &lt;krzysiek@podlesie.net&gt;
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
@@ -159,7 +159,7 @@ static void (*handlers[_NSIG])(int sig, struct siginfo *si, mcontext_t *mc) = {
 
 static void hard_handler(int sig, siginfo_t *si, void *p)
 {
-	struct ucontext *uc = p;
+	ucontext_t *uc = p;
 	mcontext_t *mc = &uc->uc_mcontext;
 	unsigned long pending = 1UL << sig;
 
diff --git a/arch/x86/um/stub_segv.c b/arch/x86/um/stub_segv.c
@@ -10,7 +10,7 @@
 void __attribute__ ((__section__ (".__syscall_stub")))
 stub_segv_handler(int sig, siginfo_t *info, void *p)
 {
-	struct ucontext *uc = p;
+	ucontext_t *uc = p;
 
 	GET_FAULTINFO_FROM_MC(*((struct faultinfo *) STUB_DATA),
 			      &uc->uc_mcontext);

Original file line number	Diff line number	Diff line change
`@@ -159,7 +159,7 @@ static void (handlers[_NSIG])(int sig, struct siginfo si, mcontext_t *mc) = {`
`159`	`159`
`160`	`160`	`static void hard_handler(int sig, siginfo_t si, void p)`
`161`	`161`	`{`
`162`		`- struct ucontext *uc = p;`
	`162`	`+ ucontext_t *uc = p;`
`163`	`163`	`mcontext_t *mc = &uc->uc_mcontext;`
`164`	`164`	`unsigned long pending = 1UL << sig;`
`165`	`165`
Original file line number	Diff line number	Diff line change
`@@ -10,7 +10,7 @@`
`10`	`10`	`void __attribute__ ((__section__ (".__syscall_stub")))`
`11`	`11`	`stub_segv_handler(int sig, siginfo_t info, void p)`
`12`	`12`	`{`
`13`		`- struct ucontext *uc = p;`
	`13`	`+ ucontext_t *uc = p;`
`14`	`14`
`15`	`15`	`GET_FAULTINFO_FROM_MC(((struct faultinfo ) STUB_DATA),`
`16`	`16`	`&uc->uc_mcontext);`