um: use POSIX ucontext_t instead of struct ucontext
diff mbox series

Message ID 20171115101239.4882-1-krzysiek@podlesie.net
State New, archived
Headers show
Series
  • um: use POSIX ucontext_t instead of struct ucontext
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Commit Message

Krzysztof Mazur Nov. 15, 2017, 10:12 a.m. UTC
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 = &uc->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'
          &uc->uc_mcontext);

Signed-off-by: Krzysztof Mazur <krzysiek@podlesie.net>
---
Tested only on x86.

 arch/um/os-Linux/signal.c | 2 +-
 arch/x86/um/stub_segv.c   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

Comments

Richard Weinberger Nov. 15, 2017, 10:19 a.m. UTC | #1
Am Mittwoch, 15. November 2017, 11:12:39 CET schrieb Krzysztof Mazur:
> 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 = &uc->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' &uc->uc_mcontext);

Do all older glibcs have ucontext_t?
Otherwise this patch will break other stuff.

Thanks,
//richard
Krzysztof Mazur Nov. 15, 2017, 11:04 a.m. UTC | #2
On Wed, Nov 15, 2017 at 11:19:41AM +0100, Richard Weinberger wrote:
> Am Mittwoch, 15. November 2017, 11:12:39 CET schrieb Krzysztof Mazur:
> > 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 = &uc->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' &uc->uc_mcontext);
> 
> Do all older glibcs have ucontext_t?
> Otherwise this patch will break other stuff.

Yes, ucontext_t typedef was always available. They changed:

typedef struct ucontext { ... } ucontex_t;

to

typedef struct ucontext_t { ... } ucontex_t;

https://sourceware.org/glibc/wiki/Release/2.26#Removal_of_.27struct_ucontext.27

Thanks,
Krzysiek
Richard Weinberger Nov. 15, 2017, 11:15 a.m. UTC | #3
Am Mittwoch, 15. November 2017, 12:04:16 CET schrieb Krzysztof Mazur:
> On Wed, Nov 15, 2017 at 11:19:41AM +0100, Richard Weinberger wrote:
> > Am Mittwoch, 15. November 2017, 11:12:39 CET schrieb Krzysztof Mazur:
> > > 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 = &uc->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' &uc->uc_mcontext);
> > 
> > Do all older glibcs have ucontext_t?
> > Otherwise this patch will break other stuff.
> 
> Yes, ucontext_t typedef was always available. They changed:
> 
> typedef struct ucontext { ... } ucontex_t;
> 
> to
> 
> typedef struct ucontext_t { ... } ucontex_t;
> 
> https://sourceware.org/glibc/wiki/Release/2.26#Removal_of_.27struct_ucontext
> .27

Okay, then we can mark your patch as stable and hope for the best. ;-)

Thanks,
//richard
Krzysztof Mazur Nov. 15, 2017, 11:22 a.m. UTC | #4
On Wed, Nov 15, 2017 at 12:15:00PM +0100, Richard Weinberger wrote:
> Am Mittwoch, 15. November 2017, 12:04:16 CET schrieb Krzysztof Mazur:
> > On Wed, Nov 15, 2017 at 11:19:41AM +0100, Richard Weinberger wrote:
> > > Am Mittwoch, 15. November 2017, 11:12:39 CET schrieb Krzysztof Mazur:
> > > > 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 = &uc->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' &uc->uc_mcontext);
> > > 
> > > Do all older glibcs have ucontext_t?
> > > Otherwise this patch will break other stuff.
> > 
> > Yes, ucontext_t typedef was always available. They changed:
> > 
> > typedef struct ucontext { ... } ucontex_t;
> > 
> > to
> > 
> > typedef struct ucontext_t { ... } ucontex_t;
> > 
> > https://sourceware.org/glibc/wiki/Release/2.26#Removal_of_.27struct_ucontext
> > .27
> 
> Okay, then we can mark your patch as stable and hope for the best. ;-)

Thanks

Krzysiek

Patch
diff mbox series

diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index a86d7cc2c2d8..a5c0c909c48b 100644
--- 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
index 1518d2805ae8..fd6825537b97 100644
--- 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);