[RFC PATCH V2 06/38] riscv: u64ilp32: Add signal support for compat

[guoren]

From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>

The u64ilp32 reuses compat mode on the 64-bit Linux kernel, but the
signal context is the same as the native 64-bit, not u32ilp32. So use
the native signal procedure for u64ilp32 applications.

Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
Signed-off-by: Guo Ren <guoren@xxxxxxxxxx>
---
 arch/riscv/include/asm/signal32.h |  9 ++++++
 arch/riscv/kernel/compat_signal.c | 21 ++++--------
 arch/riscv/kernel/signal.c        | 53 ++++++++++++++++++++++---------
 3 files changed, 54 insertions(+), 29 deletions(-)

diff --git a/arch/riscv/include/asm/signal32.h b/arch/riscv/include/asm/signal32.h
index 96dc56932e76..cda62d7eb0a5 100644
--- a/arch/riscv/include/asm/signal32.h
+++ b/arch/riscv/include/asm/signal32.h
@@ -6,6 +6,7 @@
 #if IS_ENABLED(CONFIG_COMPAT)
 int compat_setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 			  struct pt_regs *regs);
+long __riscv_compat_rt_sigreturn(void);
 #else
 static inline
 int compat_setup_rt_frame(struct ksignal *ksig, sigset_t *set,
@@ -13,6 +14,14 @@ int compat_setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 {
 	return -1;
 }
+
+static inline
+long __riscv_compat_rt_sigreturn(void)
+{
+	return -1;
+}
 #endif
 
+void __riscv_rt_sigreturn_badframe(void);
+
 #endif
diff --git a/arch/riscv/kernel/compat_signal.c b/arch/riscv/kernel/compat_signal.c
index 8dea2012836e..955a638da2a4 100644
--- a/arch/riscv/kernel/compat_signal.c
+++ b/arch/riscv/kernel/compat_signal.c
@@ -116,18 +116,16 @@ static long compat_restore_sigcontext(struct pt_regs *regs,
 	return err;
 }
 
-COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
+long __riscv_compat_rt_sigreturn(void)
 {
-	struct pt_regs *regs = current_pt_regs();
-	struct compat_rt_sigframe __user *frame;
-	struct task_struct *task;
 	sigset_t set;
+	struct pt_regs *regs = current_pt_regs();
+	struct compat_rt_sigframe __user *frame =
+		(struct compat_rt_sigframe __user *)kernel_stack_pointer(regs);
 
 	/* Always make any pending restarted system calls return -EINTR */
 	current->restart_block.fn = do_no_restart_syscall;
 
-	frame = (struct compat_rt_sigframe __user *)regs->sp;
-
 	if (!access_ok(frame, sizeof(*frame)))
 		goto badframe;
 
@@ -142,17 +140,12 @@ COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
 	if (compat_restore_altstack(&frame->uc.uc_stack))
 		goto badframe;
 
+	regs->cause = -1UL;
+
 	return regs->a0;
 
 badframe:
-	task = current;
-	if (show_unhandled_signals) {
-		pr_info_ratelimited(
-			"%s[%d]: bad frame in %s: frame=%p pc=%p sp=%p\n",
-			task->comm, task_pid_nr(task), __func__,
-			frame, (void *)regs->epc, (void *)regs->sp);
-	}
-	force_sig(SIGSEGV);
+	__riscv_rt_sigreturn_badframe();
 	return 0;
 }
 
diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c
index 95c4a8d8a3f5..1c51a6783c98 100644
--- a/arch/riscv/kernel/signal.c
+++ b/arch/riscv/kernel/signal.c
@@ -224,19 +224,34 @@ static size_t get_rt_frame_size(bool cal_all)
 	return frame_size;
 }
 
-SYSCALL_DEFINE0(rt_sigreturn)
+void __riscv_rt_sigreturn_badframe(void)
+{
+	struct task_struct *task = current;
+	struct pt_regs *regs = task_pt_regs(task);
+
+	if (show_unhandled_signals) {
+		pr_info_ratelimited(
+			"%s[%d]: bad frame in %s: frame=%p pc=%p sp=%p\n",
+			task->comm, task_pid_nr(task), __func__,
+			(void *)kernel_stack_pointer(regs),
+			(void *)instruction_pointer(regs),
+			(void *)kernel_stack_pointer(regs));
+	}
+
+	force_sig(SIGSEGV);
+}
+
+static long __riscv_rt_sigreturn(void)
 {
-	struct pt_regs *regs = current_pt_regs();
-	struct rt_sigframe __user *frame;
-	struct task_struct *task;
 	sigset_t set;
 	size_t frame_size = get_rt_frame_size(false);
+	struct pt_regs *regs = current_pt_regs();
+	struct rt_sigframe __user *frame =
+		(struct rt_sigframe __user *)kernel_stack_pointer(regs);
 
 	/* Always make any pending restarted system calls return -EINTR */
 	current->restart_block.fn = do_no_restart_syscall;
 
-	frame = (struct rt_sigframe __user *)regs->sp;
-
 	if (!access_ok(frame, frame_size))
 		goto badframe;
 
@@ -256,17 +271,25 @@ SYSCALL_DEFINE0(rt_sigreturn)
 	return regs->a0;
 
 badframe:
-	task = current;
-	if (show_unhandled_signals) {
-		pr_info_ratelimited(
-			"%s[%d]: bad frame in %s: frame=%p pc=%p sp=%p\n",
-			task->comm, task_pid_nr(task), __func__,
-			frame, (void *)regs->epc, (void *)regs->sp);
-	}
-	force_sig(SIGSEGV);
+	__riscv_rt_sigreturn_badframe();
 	return 0;
 }
 
+SYSCALL_DEFINE0(rt_sigreturn)
+{
+	return __riscv_rt_sigreturn();
+}
+
+#ifdef CONFIG_COMPAT
+COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
+{
+	if (test_thread_flag(TIF_32BIT) && !test_thread_flag(TIF_64ILP32))
+		return __riscv_compat_rt_sigreturn();
+	else
+		return __riscv_rt_sigreturn();
+}
+#endif
+
 static long setup_sigcontext(struct rt_sigframe __user *frame,
 	struct pt_regs *regs)
 {
@@ -433,7 +456,7 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 	rseq_signal_deliver(ksig, regs);
 
 	/* Set up the stack frame */
-	if (is_compat_task())
+	if (test_thread_flag(TIF_32BIT) && !test_thread_flag(TIF_64ILP32))
 		ret = compat_setup_rt_frame(ksig, oldset, regs);
 	else
 		ret = setup_rt_frame(ksig, oldset, regs);
-- 
2.36.1