powerpc/signal32: Switch handle_rt_signal32() to user_access_begin() logic

On the same way as handle_signal32(), replace all user
accesses with equivalent unsafe_ versions, and move the
trampoline code icache flush outside the user access block.

Functions that have no unsafe_ equivalent also remains outside
the access block.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/2974314226256f958e2984912b48883ef1754185.1597770847.git.christophe.leroy@csgroup.eu

diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index fc8ba4b..93c2d63 100644 (file)
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -58,8 +58,6 @@
 #define mcontext       mcontext32
 #define ucontext       ucontext32
 
-#define __save_altstack __compat_save_altstack
-
 /*
  * Userspace code may pass a ucontext which doesn't include VSX added
  * at the end.  We need to check for this case.
@@ -745,16 +743,28 @@ int handle_rt_signal32(struct ksignal *ksig, sigset_t *oldset,
 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
        tm_mctx = &frame->uc_transact.uc_mcontext;
 #endif
-       if (!access_ok(frame, sizeof(*frame)))
+       if (!user_write_access_begin(frame, sizeof(*frame)))
                goto badframe;
 
        /* Put the siginfo & fill in most of the ucontext */
-       if (copy_siginfo_to_user(&frame->info, &ksig->info) ||
-           __put_user(0, &frame->uc.uc_flags) ||
-           __save_altstack(&frame->uc.uc_stack, regs->gpr[1]) ||
-           __put_user(to_user_ptr(&frame->uc.uc_mcontext), &frame->uc.uc_regs) ||
-           put_sigset_t(&frame->uc.uc_sigmask, oldset))
-               goto badframe;
+       unsafe_put_user(0, &frame->uc.uc_flags, failed);
+#ifdef CONFIG_PPC64
+       unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->gpr[1], failed);
+#else
+       unsafe_save_altstack(&frame->uc.uc_stack, regs->gpr[1], failed);
+#endif
+       unsafe_put_user(to_user_ptr(&frame->uc.uc_mcontext), &frame->uc.uc_regs, failed);
+
+       if (MSR_TM_ACTIVE(msr)) {
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+               unsafe_put_user((unsigned long)&frame->uc_transact,
+                               &frame->uc.uc_link, failed);
+               unsafe_put_user((unsigned long)tm_mctx,
+                               &frame->uc_transact.uc_regs, failed);
+#endif
+       } else {
+               unsafe_put_user(0, &frame->uc.uc_link, failed);
+       }
 
        /* Save user registers on the stack */
        if (vdso32_rt_sigtramp && tsk->mm->context.vdso_base) {
@@ -762,28 +772,28 @@ int handle_rt_signal32(struct ksignal *ksig, sigset_t *oldset,
        } else {
                tramp = (unsigned long)mctx->mc_pad;
                /* Set up the sigreturn trampoline: li r0,sigret; sc */
-               if (__put_user(PPC_INST_ADDI + __NR_sigreturn, &mctx->mc_pad[0]))
-                       goto badframe;
-               if (__put_user(PPC_INST_SC, &mctx->mc_pad[1]))
-                       goto badframe;
-               flush_icache_range(tramp, tramp + 2 * sizeof(unsigned long));
+               unsafe_put_user(PPC_INST_ADDI + __NR_rt_sigreturn, &mctx->mc_pad[0],
+                               failed);
+               unsafe_put_user(PPC_INST_SC, &mctx->mc_pad[1], failed);
        }
+       user_write_access_end();
+
+       if (put_sigset_t(&frame->uc.uc_sigmask, oldset))
+               goto badframe;
+       if (copy_siginfo_to_user(&frame->info, &ksig->info))
+               goto badframe;
+
+       if (tramp == (unsigned long)mctx->mc_pad)
+               flush_icache_range(tramp, tramp + 2 * sizeof(unsigned long));
 
 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
        if (MSR_TM_ACTIVE(msr)) {
-               if (__put_user((unsigned long)&frame->uc_transact,
-                              &frame->uc.uc_link) ||
-                   __put_user((unsigned long)tm_mctx,
-                              &frame->uc_transact.uc_regs))
-                       goto badframe;
                if (save_tm_user_regs(regs, mctx, tm_mctx, msr))
                        goto badframe;
        }
        else
 #endif
        {
-               if (__put_user(0, &frame->uc.uc_link))
-                       goto badframe;
                if (save_user_regs(regs, mctx, tm_mctx, 1))
                        goto badframe;
        }
@@ -810,6 +820,9 @@ int handle_rt_signal32(struct ksignal *ksig, sigset_t *oldset,
        regs->msr |= (MSR_KERNEL & MSR_LE);
        return 0;
 
+failed:
+       user_write_access_end();
+
 badframe:
        signal_fault(tsk, regs, "handle_rt_signal32", frame);