Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal

Pull signal handling cleanups from Al Viro:
 "sigaltstack infrastructure + conversion for x86, alpha and um,
  COMPAT_SYSCALL_DEFINE infrastructure.

  Note that there are several conflicts between "unify
  SS_ONSTACK/SS_DISABLE definitions" and UAPI patches in mainline;
  resolution is trivial - just remove definitions of SS_ONSTACK and
  SS_DISABLED from arch/*/uapi/asm/signal.h; they are all identical and
  include/uapi/linux/signal.h contains the unified variant."

Fixed up conflicts as per Al.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal:
  alpha: switch to generic sigaltstack
  new helpers: __save_altstack/__compat_save_altstack, switch x86 and um to those
  generic compat_sys_sigaltstack()
  introduce generic sys_sigaltstack(), switch x86 and um to it
  new helper: compat_user_stack_pointer()
  new helper: restore_altstack()
  unify SS_ONSTACK/SS_DISABLE definitions
  new helper: current_user_stack_pointer()
  missing user_stack_pointer() instances
  Bury the conditionals from kernel_thread/kernel_execve series
  COMPAT_SYSCALL_DEFINE: infrastructure

19 files changed, 24 insertions, 118 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 97f8c5ad8c2d..79795af59810 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -110,11 +110,10 @@ config X86
         select GENERIC_STRNLEN_USER
         select HAVE_CONTEXT_TRACKING if X86_64
         select HAVE_IRQ_TIME_ACCOUNTING
-        select GENERIC_KERNEL_THREAD
-        select GENERIC_KERNEL_EXECVE
         select MODULES_USE_ELF_REL if X86_32
         select MODULES_USE_ELF_RELA if X86_64
         select CLONE_BACKWARDS if X86_32
+        select GENERIC_SIGALTSTACK
 
 config INSTRUCTION_DECODER
         def_bool y
diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index efc6a958b71d..a1daf4a65009 100644
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -136,52 +136,6 @@ asmlinkage long sys32_sigsuspend(int history0, int history1, old_sigset_t mask)
         return sigsuspend(&blocked);
 }
 
-asmlinkage long sys32_sigaltstack(const stack_ia32_t __user *uss_ptr,
-                                  stack_ia32_t __user *uoss_ptr,
-                                  struct pt_regs *regs)
-{
-        stack_t uss, uoss;
-        int ret, err = 0;
-        mm_segment_t seg;
-
-        if (uss_ptr) {
-                u32 ptr;
-
-                memset(&uss, 0, sizeof(stack_t));
-                if (!access_ok(VERIFY_READ, uss_ptr, sizeof(stack_ia32_t)))
-                        return -EFAULT;
-
-                get_user_try {
-                        get_user_ex(ptr, &uss_ptr->ss_sp);
-                        get_user_ex(uss.ss_flags, &uss_ptr->ss_flags);
-                        get_user_ex(uss.ss_size, &uss_ptr->ss_size);
-                } get_user_catch(err);
-
-                if (err)
-                        return -EFAULT;
-                uss.ss_sp = compat_ptr(ptr);
-        }
-        seg = get_fs();
-        set_fs(KERNEL_DS);
-        ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
-                             (stack_t __force __user *) &uoss, regs->sp);
-        set_fs(seg);
-        if (ret >= 0 && uoss_ptr)  {
-                if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(stack_ia32_t)))
-                        return -EFAULT;
-
-                put_user_try {
-                        put_user_ex(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp);
-                        put_user_ex(uoss.ss_flags, &uoss_ptr->ss_flags);
-                        put_user_ex(uoss.ss_size, &uoss_ptr->ss_size);
-                } put_user_catch(err);
-
-                if (err)
-                        ret = -EFAULT;
-        }
-        return ret;
-}
-
 /*
  * Do a signal return; undo the signal stack.
  */
@@ -292,7 +246,6 @@ asmlinkage long sys32_rt_sigreturn(struct pt_regs *regs)
         struct rt_sigframe_ia32 __user *frame;
         sigset_t set;
         unsigned int ax;
-        struct pt_regs tregs;
 
         frame = (struct rt_sigframe_ia32 __user *)(regs->sp - 4);
 
@@ -306,8 +259,7 @@ asmlinkage long sys32_rt_sigreturn(struct pt_regs *regs)
         if (ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
                 goto badframe;
 
-        tregs = *regs;
-        if (sys32_sigaltstack(&frame->uc.uc_stack, NULL, &tregs) == -EFAULT)
+        if (compat_restore_altstack(&frame->uc.uc_stack))
                 goto badframe;
 
         return ax;
@@ -515,10 +467,7 @@ int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
                 else
                         put_user_ex(0, &frame->uc.uc_flags);
                 put_user_ex(0, &frame->uc.uc_link);
-                put_user_ex(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
-                put_user_ex(sas_ss_flags(regs->sp),
-                            &frame->uc.uc_stack.ss_flags);
-                put_user_ex(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
+                err |= __compat_save_altstack(&frame->uc.uc_stack, regs->sp);
 
                 if (ka->sa.sa_flags & SA_RESTORER)
                         restorer = ka->sa.sa_restorer;
diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S
index 32e6f05ddaaa..102ff7cb3e41 100644
--- a/arch/x86/ia32/ia32entry.S
+++ b/arch/x86/ia32/ia32entry.S
@@ -464,7 +464,6 @@ GLOBAL(\label)
 
         PTREGSCALL stub32_rt_sigreturn, sys32_rt_sigreturn, %rdi
         PTREGSCALL stub32_sigreturn, sys32_sigreturn, %rdi
-        PTREGSCALL stub32_sigaltstack, sys32_sigaltstack, %rdx
         PTREGSCALL stub32_execve, compat_sys_execve, %rcx
         PTREGSCALL stub32_fork, sys_fork, %rdi
         PTREGSCALL stub32_vfork, sys_vfork, %rdi
diff --git a/arch/x86/include/asm/ia32.h b/arch/x86/include/asm/ia32.h
index e6232773ce49..4c6da2e4bb1d 100644
--- a/arch/x86/include/asm/ia32.h
+++ b/arch/x86/include/asm/ia32.h
@@ -29,16 +29,10 @@ struct old_sigaction32 {
         unsigned int sa_restorer;       /* Another 32 bit pointer */
 };
 
-typedef struct sigaltstack_ia32 {
-        unsigned int    ss_sp;
-        int             ss_flags;
-        unsigned int    ss_size;
-} stack_ia32_t;
-
 struct ucontext_ia32 {
         unsigned int      uc_flags;
         unsigned int      uc_link;
-        stack_ia32_t      uc_stack;
+        compat_stack_t    uc_stack;
         struct sigcontext_ia32 uc_mcontext;
         compat_sigset_t   uc_sigmask;   /* mask last for extensibility */
 };
@@ -46,7 +40,7 @@ struct ucontext_ia32 {
 struct ucontext_x32 {
         unsigned int      uc_flags;
         unsigned int      uc_link;
-        stack_ia32_t      uc_stack;
+        compat_stack_t    uc_stack;
         unsigned int      uc__pad0;     /* needed for alignment */
         struct sigcontext uc_mcontext;  /* the 64-bit sigcontext type */
         compat_sigset_t   uc_sigmask;   /* mask last for extensibility */
diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 03ca442d8f0d..942a08623a1a 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -133,6 +133,13 @@ static inline bool user_64bit_mode(struct pt_regs *regs)
         return regs->cs == __USER_CS || regs->cs == pv_info.extra_user_64bit_cs;
 #endif
 }
+
+#define current_user_stack_pointer()    this_cpu_read(old_rsp)
+/* ia32 vs. x32 difference */
+#define compat_user_stack_pointer()     \
+        (test_thread_flag(TIF_IA32)     \
+         ? current_pt_regs()->sp        \
+         : this_cpu_read(old_rsp))
 #endif
 
 #ifdef CONFIG_X86_32
diff --git a/arch/x86/include/asm/sys_ia32.h b/arch/x86/include/asm/sys_ia32.h
index c76fae4d90be..31f61f96e0fb 100644
--- a/arch/x86/include/asm/sys_ia32.h
+++ b/arch/x86/include/asm/sys_ia32.h
@@ -69,8 +69,6 @@ asmlinkage long sys32_fallocate(int, int, unsigned,
 
 /* ia32/ia32_signal.c */
 asmlinkage long sys32_sigsuspend(int, int, old_sigset_t);
-asmlinkage long sys32_sigaltstack(const stack_ia32_t __user *,
-                                  stack_ia32_t __user *, struct pt_regs *);
 asmlinkage long sys32_sigreturn(struct pt_regs *);
 asmlinkage long sys32_rt_sigreturn(struct pt_regs *);
 
diff --git a/arch/x86/include/asm/syscalls.h b/arch/x86/include/asm/syscalls.h
index 2f8374718aa3..58b7e3eac0ae 100644
--- a/arch/x86/include/asm/syscalls.h
+++ b/arch/x86/include/asm/syscalls.h
@@ -25,9 +25,6 @@ asmlinkage int sys_modify_ldt(int, void __user *, unsigned long);
 
 /* kernel/signal.c */
 long sys_rt_sigreturn(struct pt_regs *);
-long sys_sigaltstack(const stack_t __user *, stack_t __user *,
-                     struct pt_regs *);
-
 
 /* kernel/tls.c */
 asmlinkage int sys_set_thread_area(struct user_desc __user *);
diff --git a/arch/x86/include/asm/unistd.h b/arch/x86/include/asm/unistd.h
index 1003e69a40d9..a0790e07ba65 100644
--- a/arch/x86/include/asm/unistd.h
+++ b/arch/x86/include/asm/unistd.h
@@ -48,7 +48,6 @@
 # define __ARCH_WANT_SYS_TIME
 # define __ARCH_WANT_SYS_UTIME
 # define __ARCH_WANT_SYS_WAITPID
-# define __ARCH_WANT_SYS_EXECVE
 # define __ARCH_WANT_SYS_FORK
 # define __ARCH_WANT_SYS_VFORK
 # define __ARCH_WANT_SYS_CLONE
diff --git a/arch/x86/include/uapi/asm/signal.h b/arch/x86/include/uapi/asm/signal.h
index 0818f9a8e889..aa7d6ae39e0e 100644
--- a/arch/x86/include/uapi/asm/signal.h
+++ b/arch/x86/include/uapi/asm/signal.h
@@ -87,12 +87,6 @@ typedef unsigned long sigset_t;
 
 #define SA_RESTORER     0x04000000
 
-/*
- * sigaltstack controls
- */
-#define SS_ONSTACK      1
-#define SS_DISABLE      2
-
 #define MINSIGSTKSZ     2048
 #define SIGSTKSZ        8192
 
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index c763116c5359..ff84d5469d77 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -739,7 +739,6 @@ ENTRY(ptregs_##name) ; \
 ENDPROC(ptregs_##name)
 
 PTREGSCALL1(iopl)
-PTREGSCALL2(sigaltstack)
 PTREGSCALL0(sigreturn)
 PTREGSCALL0(rt_sigreturn)
 PTREGSCALL2(vm86)
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 70641aff0c25..07a7a04529bc 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -864,7 +864,6 @@ END(stub_\func)
         FORK_LIKE  clone
         FORK_LIKE  fork
         FORK_LIKE  vfork
-        PTREGSCALL stub_sigaltstack, sys_sigaltstack, %rdx
         PTREGSCALL stub_iopl, sys_iopl, %rsi
 
 ENTRY(ptregscall_common)
@@ -913,8 +912,6 @@ ENTRY(stub_rt_sigreturn)
 END(stub_rt_sigreturn)
 
 #ifdef CONFIG_X86_X32_ABI
-        PTREGSCALL stub_x32_sigaltstack, sys32_sigaltstack, %rdx
-
 ENTRY(stub_x32_rt_sigreturn)
         CFI_STARTPROC
         addq $8, %rsp
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index fbbb604313a2..d6bf1f34a6e9 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -364,10 +364,7 @@ static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
                 else
                         put_user_ex(0, &frame->uc.uc_flags);
                 put_user_ex(0, &frame->uc.uc_link);
-                put_user_ex(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
-                put_user_ex(sas_ss_flags(regs->sp),
-                            &frame->uc.uc_stack.ss_flags);
-                put_user_ex(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
+                err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
 
                 /* Set up to return from userspace.  */
                 restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
@@ -414,7 +411,6 @@ static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
         struct rt_sigframe __user *frame;
         void __user *fp = NULL;
         int err = 0;
-        struct task_struct *me = current;
 
         frame = get_sigframe(ka, regs, sizeof(struct rt_sigframe), &fp);
 
@@ -433,10 +429,7 @@ static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
                 else
                         put_user_ex(0, &frame->uc.uc_flags);
                 put_user_ex(0, &frame->uc.uc_link);
-                put_user_ex(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
-                put_user_ex(sas_ss_flags(regs->sp),
-                            &frame->uc.uc_stack.ss_flags);
-                put_user_ex(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
+                err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
 
                 /* Set up to return from userspace.  If provided, use a stub
                    already in userspace.  */
@@ -503,10 +496,7 @@ static int x32_setup_rt_frame(int sig, struct k_sigaction *ka,
                 else
                         put_user_ex(0, &frame->uc.uc_flags);
                 put_user_ex(0, &frame->uc.uc_link);
-                put_user_ex(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
-                put_user_ex(sas_ss_flags(regs->sp),
-                            &frame->uc.uc_stack.ss_flags);
-                put_user_ex(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
+                err |= __compat_save_altstack(&frame->uc.uc_stack, regs->sp);
                 put_user_ex(0, &frame->uc.uc__pad0);
 
                 if (ka->sa.sa_flags & SA_RESTORER) {
@@ -603,13 +593,6 @@ sys_sigaction(int sig, const struct old_sigaction __user *act,
 }
 #endif /* CONFIG_X86_32 */
 
-long
-sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
-                struct pt_regs *regs)
-{
-        return do_sigaltstack(uss, uoss, regs->sp);
-}
-
 /*
  * Do a signal return; undo the signal stack.
  */
@@ -659,7 +642,7 @@ long sys_rt_sigreturn(struct pt_regs *regs)
         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
                 goto badframe;
 
-        if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
+        if (restore_altstack(&frame->uc.uc_stack))
                 goto badframe;
 
         return ax;
@@ -865,7 +848,6 @@ asmlinkage long sys32_x32_rt_sigreturn(struct pt_regs *regs)
         struct rt_sigframe_x32 __user *frame;
         sigset_t set;
         unsigned long ax;
-        struct pt_regs tregs;
 
         frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
 
@@ -879,8 +861,7 @@ asmlinkage long sys32_x32_rt_sigreturn(struct pt_regs *regs)
         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
                 goto badframe;
 
-        tregs = *regs;
-        if (sys32_sigaltstack(&frame->uc.uc_stack, NULL, &tregs) == -EFAULT)
+        if (compat_restore_altstack(&frame->uc.uc_stack))
                 goto badframe;
 
         return ax;
diff --git a/arch/x86/syscalls/syscall_32.tbl b/arch/x86/syscalls/syscall_32.tbl
index 05f404f53f59..28e3fa9056ea 100644
--- a/arch/x86/syscalls/syscall_32.tbl
+++ b/arch/x86/syscalls/syscall_32.tbl
@@ -192,7 +192,7 @@
 183     i386    getcwd                  sys_getcwd
 184     i386    capget                  sys_capget
 185     i386    capset                  sys_capset
-186     i386    sigaltstack             ptregs_sigaltstack              stub32_sigaltstack
+186     i386    sigaltstack             sys_sigaltstack                 compat_sys_sigaltstack
 187     i386    sendfile                sys_sendfile                    sys32_sendfile
 188     i386    getpmsg
 189     i386    putpmsg
diff --git a/arch/x86/syscalls/syscall_64.tbl b/arch/x86/syscalls/syscall_64.tbl
index 7c58c84b7bc8..dc97328bd90a 100644
--- a/arch/x86/syscalls/syscall_64.tbl
+++ b/arch/x86/syscalls/syscall_64.tbl
@@ -137,7 +137,7 @@
 128     64      rt_sigtimedwait         sys_rt_sigtimedwait
 129     64      rt_sigqueueinfo         sys_rt_sigqueueinfo
 130     common  rt_sigsuspend           sys_rt_sigsuspend
-131     64      sigaltstack             stub_sigaltstack
+131     64      sigaltstack             sys_sigaltstack
 132     common  utime                   sys_utime
 133     common  mknod                   sys_mknod
 134     64      uselib
@@ -338,7 +338,7 @@
 522     x32     rt_sigpending           sys32_rt_sigpending
 523     x32     rt_sigtimedwait         compat_sys_rt_sigtimedwait
 524     x32     rt_sigqueueinfo         sys32_rt_sigqueueinfo
-525     x32     sigaltstack             stub_x32_sigaltstack
+525     x32     sigaltstack             compat_sys_sigaltstack
 526     x32     timer_create            compat_sys_timer_create
 527     x32     mq_notify               compat_sys_mq_notify
 528     x32     kexec_load              compat_sys_kexec_load
diff --git a/arch/x86/um/Kconfig b/arch/x86/um/Kconfig
index 983997041963..53c90fd412d1 100644
--- a/arch/x86/um/Kconfig
+++ b/arch/x86/um/Kconfig
@@ -13,8 +13,7 @@ endmenu
 config UML_X86
         def_bool y
         select GENERIC_FIND_FIRST_BIT
-        select GENERIC_KERNEL_THREAD
-        select GENERIC_KERNEL_EXECVE
+        select GENERIC_SIGALTSTACK
 
 config 64BIT
         bool "64-bit kernel" if SUBARCH = "x86"
diff --git a/arch/x86/um/asm/ptrace.h b/arch/x86/um/asm/ptrace.h
index 755133258c45..54f8102ccde5 100644
--- a/arch/x86/um/asm/ptrace.h
+++ b/arch/x86/um/asm/ptrace.h
@@ -86,4 +86,5 @@ extern long arch_prctl(struct task_struct *task, int code,
                        unsigned long __user *addr);
 
 #endif
+#define user_stack_pointer(regs) PT_REGS_SP(regs)
 #endif /* __UM_X86_PTRACE_H */
diff --git a/arch/x86/um/signal.c b/arch/x86/um/signal.c
index bdaa08cfbcf4..71cef48ea5cd 100644
--- a/arch/x86/um/signal.c
+++ b/arch/x86/um/signal.c
@@ -342,9 +342,7 @@ static int copy_ucontext_to_user(struct ucontext __user *uc,
 {
         int err = 0;
 
-        err |= put_user(current->sas_ss_sp, &uc->uc_stack.ss_sp);
-        err |= put_user(sas_ss_flags(sp), &uc->uc_stack.ss_flags);
-        err |= put_user(current->sas_ss_size, &uc->uc_stack.ss_size);
+        err |= __save_altstack(&uc->uc_stack, sp);
         err |= copy_sc_to_user(&uc->uc_mcontext, fp, &current->thread.regs, 0);
         err |= copy_to_user(&uc->uc_sigmask, set, sizeof(*set));
         return err;
@@ -529,10 +527,7 @@ int setup_signal_stack_si(unsigned long stack_top, int sig,
         /* Create the ucontext.  */
         err |= __put_user(0, &frame->uc.uc_flags);
         err |= __put_user(0, &frame->uc.uc_link);
-        err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
-        err |= __put_user(sas_ss_flags(PT_REGS_SP(regs)),
-                          &frame->uc.uc_stack.ss_flags);
-        err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
+        err |= __save_altstack(&frame->uc.uc_stack, PT_REGS_SP(regs));
         err |= copy_sc_to_user(&frame->uc.uc_mcontext, &frame->fpstate, regs,
                                set->sig[0]);
         err |= __put_user(&frame->fpstate, &frame->uc.uc_mcontext.fpstate);
diff --git a/arch/x86/um/sys_call_table_32.c b/arch/x86/um/sys_call_table_32.c
index 812e98c098e4..a0c3b0d1a122 100644
--- a/arch/x86/um/sys_call_table_32.c
+++ b/arch/x86/um/sys_call_table_32.c
@@ -27,7 +27,6 @@
 #define ptregs_iopl sys_iopl
 #define ptregs_vm86old sys_vm86old
 #define ptregs_vm86 sys_vm86
-#define ptregs_sigaltstack sys_sigaltstack
 
 #define __SYSCALL_I386(nr, sym, compat) extern asmlinkage void sym(void) ;
 #include <asm/syscalls_32.h>
diff --git a/arch/x86/um/sys_call_table_64.c b/arch/x86/um/sys_call_table_64.c
index 170bd926a69c..f2f0723070ca 100644
--- a/arch/x86/um/sys_call_table_64.c
+++ b/arch/x86/um/sys_call_table_64.c
@@ -31,7 +31,6 @@
 #define stub_fork sys_fork
 #define stub_vfork sys_vfork
 #define stub_execve sys_execve
-#define stub_sigaltstack sys_sigaltstack
 #define stub_rt_sigreturn sys_rt_sigreturn
 
 #define __SYSCALL_COMMON(nr, sym, compat) __SYSCALL_64(nr, sym, compat)