arm64: switch to generic sigaltstack

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

8 files changed, 6 insertions, 80 deletions

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index f8f362aafee9..d9c901dd3fdb 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -10,6 +10,7 @@ config ARM64
         select GENERIC_IOMAP
         select GENERIC_IRQ_PROBE
         select GENERIC_IRQ_SHOW
+        select GENERIC_SIGALTSTACK
         select GENERIC_SMP_IDLE_THREAD
         select GENERIC_TIME_VSYSCALL
         select HARDIRQS_SW_RESEND
diff --git a/arch/arm64/include/asm/syscalls.h b/arch/arm64/include/asm/syscalls.h
index 20d63b290665..48fe7c600e98 100644
--- a/arch/arm64/include/asm/syscalls.h
+++ b/arch/arm64/include/asm/syscalls.h
@@ -24,8 +24,6 @@
  * System call wrappers implemented in kernel/entry.S.
  */
 asmlinkage long sys_rt_sigreturn_wrapper(void);
-asmlinkage long sys_sigaltstack_wrapper(const stack_t __user *uss,
-                                        stack_t __user *uoss);
 
 #include <asm-generic/syscalls.h>
 
diff --git a/arch/arm64/include/asm/unistd32.h b/arch/arm64/include/asm/unistd32.h
index 5ef47ba3ed45..008406aff09f 100644
--- a/arch/arm64/include/asm/unistd32.h
+++ b/arch/arm64/include/asm/unistd32.h
@@ -207,7 +207,7 @@ __SYSCALL(182, sys_chown16)
 __SYSCALL(183, sys_getcwd)
 __SYSCALL(184, sys_capget)
 __SYSCALL(185, sys_capset)
-__SYSCALL(186, compat_sys_sigaltstack_wrapper)
+__SYSCALL(186, compat_sys_sigaltstack)
 __SYSCALL(187, compat_sys_sendfile)
 __SYSCALL(188, sys_ni_syscall)                  /* 188 reserved */
 __SYSCALL(189, sys_ni_syscall)                  /* 189 reserved */
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 9c94f404ded6..514d6098dbee 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -677,10 +677,5 @@ ENTRY(sys_rt_sigreturn_wrapper)
         b       sys_rt_sigreturn
 ENDPROC(sys_rt_sigreturn_wrapper)
 
-ENTRY(sys_sigaltstack_wrapper)
-        ldr     x2, [sp, #S_SP]
-        b       sys_sigaltstack
-ENDPROC(sys_sigaltstack_wrapper)
-
 ENTRY(handle_arch_irq)
         .quad   0
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index abd756315cb5..890a591f75dd 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -149,8 +149,7 @@ asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
         if (restore_sigframe(regs, frame))
                 goto badframe;
 
-        if (do_sigaltstack(&frame->uc.uc_stack,
-                           NULL, regs->sp) == -EFAULT)
+        if (restore_altstack(&frame->uc.uc_stack))
                 goto badframe;
 
         return regs->regs[0];
@@ -164,12 +163,6 @@ badframe:
         return 0;
 }
 
-asmlinkage long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
-                                unsigned long sp)
-{
-        return do_sigaltstack(uss, uoss, sp);
-}
-
 static int setup_sigframe(struct rt_sigframe __user *sf,
                           struct pt_regs *regs, sigset_t *set)
 {
@@ -250,7 +243,6 @@ static int setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
                           sigset_t *set, struct pt_regs *regs)
 {
         struct rt_sigframe __user *frame;
-        stack_t stack;
         int err = 0;
 
         frame = get_sigframe(ka, regs);
@@ -260,12 +252,7 @@ static int setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
         __put_user_error(0, &frame->uc.uc_flags, err);
         __put_user_error(NULL, &frame->uc.uc_link, err);
 
-        memset(&stack, 0, sizeof(stack));
-        stack.ss_sp = (void __user *)current->sas_ss_sp;
-        stack.ss_flags = sas_ss_flags(regs->sp);
-        stack.ss_size = current->sas_ss_size;
-        err |= __copy_to_user(&frame->uc.uc_stack, &stack, sizeof(stack));
-
+        err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
         err |= setup_sigframe(frame, regs, set);
         if (err == 0) {
                 setup_return(regs, ka, frame, usig);
diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index a4db3d22aac4..54920c5342b2 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -42,12 +42,6 @@ struct compat_old_sigaction {
         compat_uptr_t                   sa_restorer;
 };
 
-typedef struct compat_sigaltstack {
-        compat_uptr_t                   ss_sp;
-        int                             ss_flags;
-        compat_size_t                   ss_size;
-} compat_stack_t;
-
 struct compat_sigcontext {
         /* We always set these two fields to 0 */
         compat_ulong_t                  trap_no;
@@ -423,43 +417,6 @@ asmlinkage int compat_sys_rt_sigaction(int sig,
         return ret;
 }
 
-int compat_do_sigaltstack(compat_uptr_t compat_uss, compat_uptr_t compat_uoss,
-                          compat_ulong_t sp)
-{
-        compat_stack_t __user *newstack = compat_ptr(compat_uss);
-        compat_stack_t __user *oldstack = compat_ptr(compat_uoss);
-        compat_uptr_t ss_sp;
-        int ret;
-        mm_segment_t old_fs;
-        stack_t uss, uoss;
-
-        /* Marshall the compat new stack into a stack_t */
-        if (newstack) {
-                if (get_user(ss_sp, &newstack->ss_sp) ||
-                    __get_user(uss.ss_flags, &newstack->ss_flags) ||
-                    __get_user(uss.ss_size, &newstack->ss_size))
-                        return -EFAULT;
-                uss.ss_sp = compat_ptr(ss_sp);
-        }
-
-        old_fs = get_fs();
-        set_fs(KERNEL_DS);
-        /* The __user pointer casts are valid because of the set_fs() */
-        ret = do_sigaltstack(
-                newstack ? (stack_t __user *) &uss : NULL,
-                oldstack ? (stack_t __user *) &uoss : NULL,
-                (unsigned long)sp);
-        set_fs(old_fs);
-
-        /* Convert the old stack_t into a compat stack. */
-        if (!ret && oldstack &&
-                (put_user(ptr_to_compat(uoss.ss_sp), &oldstack->ss_sp) ||
-                 __put_user(uoss.ss_flags, &oldstack->ss_flags) ||
-                 __put_user(uoss.ss_size, &oldstack->ss_size)))
-                return -EFAULT;
-        return ret;
-}
-
 static int compat_restore_sigframe(struct pt_regs *regs,
                                    struct compat_sigframe __user *sf)
 {
@@ -562,9 +519,7 @@ asmlinkage int compat_sys_rt_sigreturn(struct pt_regs *regs)
         if (compat_restore_sigframe(regs, &frame->sig))
                 goto badframe;
 
-        if (compat_do_sigaltstack(ptr_to_compat(&frame->sig.uc.uc_stack),
-                                 ptr_to_compat((void __user *)NULL),
-                                 regs->compat_sp) == -EFAULT)
+        if (compat_restore_altstack(&frame->sig.uc.uc_stack))
                 goto badframe;
 
         return regs->regs[0];
@@ -705,11 +660,7 @@ int compat_setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
         __put_user_error(0, &frame->sig.uc.uc_flags, err);
         __put_user_error(NULL, &frame->sig.uc.uc_link, err);
 
-        memset(&stack, 0, sizeof(stack));
-        stack.ss_sp = (compat_uptr_t)current->sas_ss_sp;
-        stack.ss_flags = sas_ss_flags(regs->compat_sp);
-        stack.ss_size = current->sas_ss_size;
-        err |= __copy_to_user(&frame->sig.uc.uc_stack, &stack, sizeof(stack));
+        err |= __compat_save_altstack(&frame->sig.uc.uc_stack, regs->compat_sp);
 
         err |= compat_setup_sigframe(&frame->sig, regs, set);
 
diff --git a/arch/arm64/kernel/sys.c b/arch/arm64/kernel/sys.c
index 8292a9b090f8..3fa98ff14f0e 100644
--- a/arch/arm64/kernel/sys.c
+++ b/arch/arm64/kernel/sys.c
@@ -40,7 +40,6 @@ asmlinkage long sys_mmap(unsigned long addr, unsigned long len,
  * Wrappers to pass the pt_regs argument.
  */
 #define sys_rt_sigreturn        sys_rt_sigreturn_wrapper
-#define sys_sigaltstack         sys_sigaltstack_wrapper
 
 #include <asm/syscalls.h>
 
diff --git a/arch/arm64/kernel/sys32.S b/arch/arm64/kernel/sys32.S
index 7ef59e9245ef..6abb05721614 100644
--- a/arch/arm64/kernel/sys32.S
+++ b/arch/arm64/kernel/sys32.S
@@ -39,11 +39,6 @@ compat_sys_rt_sigreturn_wrapper:
         b       compat_sys_rt_sigreturn
 ENDPROC(compat_sys_rt_sigreturn_wrapper)
 
-compat_sys_sigaltstack_wrapper:
-        ldr     x2, [sp, #S_COMPAT_SP]
-        b       compat_do_sigaltstack
-ENDPROC(compat_sys_sigaltstack_wrapper)
-
 compat_sys_statfs64_wrapper:
         mov     w3, #84
         cmp     w1, #88