[PATCH v6 17/20] arm64: ilp32: introduce ilp32-specific handlers for sigframe

From: Yury Norov
Date: Tue Dec 15 2015 - 16:51:22 EST

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ILP32 uses AARCH32 compat structures and syscall handlers for signals.
But ILP32 struct rt_sigframe differs from both LP64 and AARCH32. So some
specific mechanism is needed to take care of it.

Signed-off-by: Yury Norov <ynorov@xxxxxxxxxxxxxxxxxx>
---
arch/arm64/include/asm/signal_ilp32.h | 38 ++++++++++
arch/arm64/kernel/Makefile | 2 +-
arch/arm64/kernel/entry_ilp32.S | 32 +++++++++
arch/arm64/kernel/signal.c | 3 +
arch/arm64/kernel/signal_ilp32.c | 126 ++++++++++++++++++++++++++++++++++
arch/arm64/kernel/sys_ilp32.c | 3 +
6 files changed, 203 insertions(+), 1 deletion(-)
create mode 100644 arch/arm64/include/asm/signal_ilp32.h
create mode 100644 arch/arm64/kernel/entry_ilp32.S
create mode 100644 arch/arm64/kernel/signal_ilp32.c

diff --git a/arch/arm64/include/asm/signal_ilp32.h b/arch/arm64/include/asm/signal_ilp32.h
new file mode 100644
index 0000000..81e1909
--- /dev/null
+++ b/arch/arm64/include/asm/signal_ilp32.h
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2015 Cavium Networks.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __ASM_SIGNAL_ILP32_H
+#define __ASM_SIGNAL_ILP32_H
+
+#ifdef __KERNEL__
+#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 /* __KERNEL__ */
+#endif /* __ASM_SIGNAL_ILP32_H */
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index f90fb08..f92e707 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -24,7 +24,7 @@ arm64-obj-$(CONFIG_AARCH32_EL0) += sys32.o kuser32.o signal32.o \
sys_compat.o entry32.o \
../../arm/kernel/opcodes.o
arm64-obj-$(CONFIG_FUNCTION_TRACER) += ftrace.o entry-ftrace.o
-arm64-obj-$(CONFIG_ARM64_ILP32) += sys_ilp32.o
+arm64-obj-$(CONFIG_ARM64_ILP32) += signal_ilp32.o sys_ilp32.o entry_ilp32.o
arm64-obj-$(CONFIG_COMPAT) += entry32-common.o signal32_common.o
arm64-obj-$(CONFIG_MODULES) += arm64ksyms.o module.o
arm64-obj-$(CONFIG_PERF_EVENTS) += perf_regs.o perf_callchain.o
diff --git a/arch/arm64/kernel/entry_ilp32.S b/arch/arm64/kernel/entry_ilp32.S
new file mode 100644
index 0000000..424060f
--- /dev/null
+++ b/arch/arm64/kernel/entry_ilp32.S
@@ -0,0 +1,32 @@
+/*
+ * ILP32 system call wrappers
+ *
+ * Copyright (C) 2015 Cavium Networks.
+ * Author: Yury Norov <ynorov@xxxxxxxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/linkage.h>
+#include <linux/const.h>
+
+#include <asm/assembler.h>
+#include <asm/asm-offsets.h>
+#include <asm/errno.h>
+#include <asm/page.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.c b/arch/arm64/kernel/signal.c
index 4b8efe5..d67a9b8 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -34,6 +34,7 @@
#include <asm/fpsimd.h>
#include <asm/signal32.h>
#include <asm/signal_common.h>
+#include <asm/signal_ilp32.h>

/*
* Do a signal return; undo the signal stack. These are aligned to 128-bit.
@@ -153,6 +154,8 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
ret = compat_setup_rt_frame(usig, ksig, oldset, regs);
else
ret = compat_setup_frame(usig, ksig, oldset, regs);
+ } else if (is_ilp32_compat_task()) {
+ ret = ilp32_setup_rt_frame(usig, ksig, oldset, regs);
} else {
ret = setup_rt_frame(usig, ksig, oldset, regs);
}
diff --git a/arch/arm64/kernel/signal_ilp32.c b/arch/arm64/kernel/signal_ilp32.c
new file mode 100644
index 0000000..d38434b
--- /dev/null
+++ b/arch/arm64/kernel/signal_ilp32.c
@@ -0,0 +1,126 @@
+/*
+ * Based on arch/arm/kernel/signal.c
+ *
+ * Copyright (C) 2015 Cavium Networks.
+ * Yury Norov <ynorov@xxxxxxxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/compat.h>
+#include <linux/signal.h>
+#include <linux/syscalls.h>
+#include <linux/ratelimit.h>
+
+#include <asm/esr.h>
+#include <asm/fpsimd.h>
+#include <asm/signal32_common.h>
+#include <asm/signal_common.h>
+#include <asm/uaccess.h>
+#include <asm/unistd.h>
+#include <asm/ucontext.h>
+
+struct ilp32_rt_sigframe {
+ struct compat_siginfo info;
+ struct sigframe sig;
+};
+
+asmlinkage int ilp32_sys_rt_sigreturn(struct pt_regs *regs)
+{
+ struct ilp32_rt_sigframe __user *frame;
+
+ /* Always make any pending restarted system calls return -EINTR */
+ current->restart_block.fn = do_no_restart_syscall;
+
+ /*
+ * Since we stacked the signal on a 64-bit boundary,
+ * then 'sp' should be word aligned here. If it's
+ * not, then the user is trying to mess with us.
+ */
+ if (regs->sp & 15)
+ goto badframe;
+
+ frame = (struct ilp32_rt_sigframe __user *)regs->sp;
+
+ if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
+ goto badframe;
+
+ if (restore_sigframe(regs, &frame->sig))
+ goto badframe;
+
+ if (restore_altstack(&frame->sig.uc.uc_stack))
+ goto badframe;
+
+ return regs->regs[0];
+
+badframe:
+ if (show_unhandled_signals)
+ pr_info_ratelimited("%s[%d]: bad frame in %s: pc=%08llx sp=%08llx\n",
+ current->comm, task_pid_nr(current), __func__,
+ regs->pc, regs->compat_sp);
+ force_sig(SIGSEGV, current);
+ return 0;
+}
+
+static struct ilp32_rt_sigframe __user *ilp32_get_sigframe(struct ksignal *ksig,
+ struct pt_regs *regs)
+{
+ unsigned long sp, sp_top;
+ struct ilp32_rt_sigframe __user *frame;
+
+ sp = sp_top = sigsp(regs->sp, ksig);
+
+ sp = (sp - sizeof(struct ilp32_rt_sigframe)) & ~15;
+ frame = (struct ilp32_rt_sigframe __user *)sp;
+
+ /*
+ * Check that we can actually write to the signal frame.
+ */
+ if (!access_ok(VERIFY_WRITE, frame, sp_top - sp))
+ frame = NULL;
+
+ return frame;
+}
+
+/*
+ * ILP32 signal handling routines called from signal.c
+ */
+int ilp32_setup_rt_frame(int usig, struct ksignal *ksig,
+ sigset_t *set, struct pt_regs *regs)
+{
+ struct ilp32_rt_sigframe __user *frame;
+ int err = 0;
+
+ frame = ilp32_get_sigframe(ksig, regs);
+
+ if (!frame)
+ return 1;
+
+ __put_user_error(0, &frame->sig.uc.uc_flags, err);
+ __put_user_error(NULL, &frame->sig.uc.uc_link, err);
+
+ err |= __save_altstack(&frame->sig.uc.uc_stack, regs->sp);
+ err |= setup_sigframe(&frame->sig, regs, set);
+ if (err == 0) {
+ setup_return(regs, &ksig->ka, frame,
+ offsetof(struct ilp32_rt_sigframe, sig), usig);
+ if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
+ err |= copy_siginfo_to_user32(&frame->info, &ksig->info);
+ regs->regs[1] = (unsigned long)&frame->info;
+ regs->regs[2] = (unsigned long)&frame->sig.uc;
+ }
+ }
+
+ return err;
+}
+
diff --git a/arch/arm64/kernel/sys_ilp32.c b/arch/arm64/kernel/sys_ilp32.c
index c282fa2..1882bb3 100644
--- a/arch/arm64/kernel/sys_ilp32.c
+++ b/arch/arm64/kernel/sys_ilp32.c
@@ -54,6 +54,9 @@ asmlinkage long compat_sys_fstatfs64_wrapper(void);
asmlinkage long compat_sys_statfs64_wrapper(void);
#define compat_sys_statfs64 compat_sys_statfs64_wrapper

+asmlinkage long ilp32_sys_rt_sigreturn_wrapper(void);
+#define compat_sys_rt_sigreturn ilp32_sys_rt_sigreturn_wrapper
+
#include <asm/syscall.h>

#undef __SYSCALL
--
2.5.0

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Next message: Yury Norov: "[PATCH v6 18/20] arm64:ilp32: add vdso-ilp32 and use for signal return"
Previous message: Yury Norov: "[PATCH v6 16/20] arm64: signal32: move ilp32 and aarch32 common code to separated file"
In reply to: Yury Norov: "[PATCH v6 16/20] arm64: signal32: move ilp32 and aarch32 common code to separated file"
Next in thread: Yury Norov: "[PATCH v6 18/20] arm64:ilp32: add vdso-ilp32 and use for signal return"
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