arm64: ilp32: introduce ilp32-specific sigframe and ucontext

ILP32 uses AARCH32 compat structures and syscall handlers for signals. But
ILP32 rt_sigframe and ucontext structures differ from both LP64 and AARCH32.
From software point of view ILP32 is typical 32-bit compat ABI, and from
hardware point of view, it's just like LP64.

struct rt_sigframe defined in this patch in
arch/arm64/kernel/signal_ilp32.c redefines one in
arch/arm64/kernel/signal.c. And functions located in
arch/arm64/include/signal_common.h pick up new structure to generate the
code suitable for ILP32.

Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>

4 files changed, 102 insertions, 1 deletions

diff --git a/arch/arm64/include/asm/signal_ilp32.h b/arch/arm64/include/asm/signal_ilp32.h
new file mode 100644
index 000000000000..7ee97c133605
--- /dev/null
+++ b/arch/arm64/include/asm/signal_ilp32.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+#ifndef __ASM_SIGNAL_ILP32_H
+#define __ASM_SIGNAL_ILP32_H
+
+#ifdef CONFIG_ARM64_ILP32
+
+#include <linux/compat.h>
+
+int ilp32_setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,
+			  struct pt_regs *regs);
+
+#else
+
+static inline int ilp32_setup_rt_frame(int usig, struct ksignal *ksig,
+					sigset_t *set, struct pt_regs *regs)
+{
+	return -ENOSYS;
+}
+
+#endif /* CONFIG_ARM64_ILP32 */
+
+#endif /* __ASM_SIGNAL_ILP32_H */
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 9e127c47a25c..27ddf5369f89 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -28,7 +28,8 @@ $(obj)/%.stub.o: $(obj)/%.o FORCE
 
 arm64-obj-$(CONFIG_AARCH32_EL0)		+= sys32.o kuser32.o signal32.o 	\
 					   sys_compat.o entry32.o binfmt_elf32.o
-arm64-obj-$(CONFIG_ARM64_ILP32)		+= binfmt_ilp32.o sys_ilp32.o
+arm64-obj-$(CONFIG_ARM64_ILP32)		+= binfmt_ilp32.o sys_ilp32.o 		\
+					   signal_ilp32.o entry_ilp32.o
 arm64-obj-$(CONFIG_COMPAT)		+= entry32_common.o signal32_common.o
 arm64-obj-$(CONFIG_FUNCTION_TRACER)	+= ftrace.o entry-ftrace.o
 arm64-obj-$(CONFIG_MODULES)		+= arm64ksyms.o module.o
diff --git a/arch/arm64/kernel/entry_ilp32.S b/arch/arm64/kernel/entry_ilp32.S
new file mode 100644
index 000000000000..562d5d0a7d82
--- /dev/null
+++ b/arch/arm64/kernel/entry_ilp32.S
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+/*
+ * ILP32 system call wrappers
+ */
+
+#include <linux/linkage.h>
+
+ENTRY(ilp32_sys_rt_sigreturn_wrapper)
+	mov	x0, sp
+	b	ilp32_sys_rt_sigreturn
+ENDPROC(ilp32_sys_rt_sigreturn_wrapper)
diff --git a/arch/arm64/kernel/signal_ilp32.c b/arch/arm64/kernel/signal_ilp32.c
new file mode 100644
index 000000000000..f4bcb7332010
--- /dev/null
+++ b/arch/arm64/kernel/signal_ilp32.c
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+/*
+ * Copyright (C) 1995-2009 Russell King
+ * Copyright (C) 2012 ARM Ltd.
+ * Copyright (C) 2018 Cavium Networks.
+ * Yury Norov <ynorov@caviumnetworks.com>
+ */
+
+#include <linux/compat.h>
+#include <linux/signal.h>
+#include <linux/syscalls.h>
+
+#include <asm/fpsimd.h>
+#include <asm/unistd.h>
+#include <asm/ucontext.h>
+#include <asm/vdso.h>
+
+#include <asm/signal_ilp32.h>
+#include <asm/signal32_common.h>
+
+#define get_sigset(s, m) get_sigset_t(s, m)
+#define put_sigset(s, m) put_sigset_t(m, s)
+
+#define restore_altstack(stack) compat_restore_altstack(stack)
+#define __save_altstack(stack, sp) __compat_save_altstack(stack, sp)
+#define copy_siginfo_to_user(frame_info, ksig_info) \
+		copy_siginfo_to_user32(frame_info, ksig_info)
+
+#define setup_return(regs, ka, user_layout, usig)			\
+{									\
+	__setup_return(regs, ka, user_layout, usig);			\
+	regs->regs[30] =						\
+		(unsigned long)VDSO_SYMBOL(current->mm->context.vdso,	\
+						    sigtramp_ilp32);	\
+}
+
+struct ilp32_ucontext {
+	u32		uc_flags;
+	u32		uc_link;
+	compat_stack_t	uc_stack;
+	compat_sigset_t	uc_sigmask;
+	/* glibc uses a 1024-bit sigset_t */
+	__u8		__unused[1024 / 8 - sizeof(compat_sigset_t)];
+	/* last for future expansion */
+	struct sigcontext uc_mcontext;
+};
+
+struct rt_sigframe {
+	struct compat_siginfo info;
+	struct ilp32_ucontext uc;
+};
+
+#include <asm/signal_common.h>
+
+asmlinkage long ilp32_sys_rt_sigreturn(struct pt_regs *regs)
+{
+	return __sys_rt_sigreturn(regs);
+}
+
+int ilp32_setup_rt_frame(int usig, struct ksignal *ksig,
+			  sigset_t *set, struct pt_regs *regs)
+{
+	return __setup_rt_frame(usig, ksig, set, regs);
+}