introduce generic sys_sigaltstack(), switch x86 and um to it

Conditional on CONFIG_GENERIC_SIGALTSTACK; architectures that do not
select it are completely unaffected

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

12 files changed, 7 insertions, 21 deletions

diff --git a/arch/Kconfig b/arch/Kconfig
index 0a8dd0585d0d..330176824594 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -335,6 +335,9 @@ config MODULES_USE_ELF_REL
           Modules only use ELF REL relocations.  Modules with ELF RELA
           relocations will give an error.
 
+config GENERIC_SIGALTSTACK
+        bool
+
 #
 # ABI hall of shame
 #
diff --git a/arch/um/kernel/signal.c b/arch/um/kernel/signal.c
index db18eb6124e1..48ccf718e290 100644
--- a/arch/um/kernel/signal.c
+++ b/arch/um/kernel/signal.c
@@ -132,8 +132,3 @@ long sys_sigsuspend(int history0, int history1, old_sigset_t mask)
         siginitset(&blocked, mask);
         return sigsuspend(&blocked);
 }
-
-long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
-{
-        return do_sigaltstack(uss, uoss, PT_REGS_SP(&current->thread.regs));
-}
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 01ca0ebaff0e..f380614d7d89 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -111,6 +111,7 @@ config X86
         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/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/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 2363e820ed68..6e462019f195 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)
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 70b27ee6118e..16d065c23baf 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -602,13 +602,6 @@ 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.
  */
diff --git a/arch/x86/syscalls/syscall_32.tbl b/arch/x86/syscalls/syscall_32.tbl
index ee3c220ee500..62c7b222e45c 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                 stub32_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 a582bfed95bb..6ffa7f9d005e 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
diff --git a/arch/x86/um/Kconfig b/arch/x86/um/Kconfig
index 0fd20f241e40..96b89d874ead 100644
--- a/arch/x86/um/Kconfig
+++ b/arch/x86/um/Kconfig
@@ -13,6 +13,7 @@ endmenu
 config UML_X86
         def_bool y
         select GENERIC_FIND_FIRST_BIT
+        select GENERIC_SIGALTSTACK
 
 config 64BIT
         bool "64-bit kernel" if SUBARCH = "x86"
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)