[PATCH v16 06/10] x86/syscalls/32: Wire up arch_prctl on x86-32

From: Kyle Huey
Date: Mon Mar 20 2017 - 12:50:33 EST


Hook up arch_prctl to call do_arch_prctl() on x86-32, and in 32 bit compat
mode on x86-64. This allows us to have arch_prctls that are not specific to
64 bits.

On UML, simply stub out this syscall.

Signed-off-by: Kyle Huey <khuey@xxxxxxxxxxxx>
---
arch/x86/entry/syscalls/syscall_32.tbl | 1 +
arch/x86/kernel/process_32.c | 7 +++++++
arch/x86/kernel/process_64.c | 7 +++++++
arch/x86/um/Makefile | 2 +-
arch/x86/um/syscalls_32.c | 7 +++++++
include/linux/compat.h | 2 ++
6 files changed, 25 insertions(+), 1 deletion(-)
create mode 100644 arch/x86/um/syscalls_32.c

diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index 9ba050fe47f3..0af59fa789ea 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -390,3 +390,4 @@
381 i386 pkey_alloc sys_pkey_alloc
382 i386 pkey_free sys_pkey_free
383 i386 statx sys_statx
+384 i386 arch_prctl sys_arch_prctl compat_sys_arch_prctl
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 4c818f8bc135..ff40e74c9181 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -37,6 +37,7 @@
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/kdebug.h>
+#include <linux/syscalls.h>

#include <asm/pgtable.h>
#include <asm/ldt.h>
@@ -56,6 +57,7 @@
#include <asm/switch_to.h>
#include <asm/vm86.h>
#include <asm/intel_rdt.h>
+#include <asm/proto.h>

void __show_regs(struct pt_regs *regs, int all)
{
@@ -304,3 +306,8 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)

return prev_p;
}
+
+SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2)
+{
+ return do_arch_prctl_common(current, option, arg2);
+}
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index d81b0a60a45c..ea1a6180bf39 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -635,6 +635,13 @@ SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2)
return ret;
}

+#ifdef CONFIG_IA32_EMULATION
+COMPAT_SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2)
+{
+ return do_arch_prctl_common(current, option, arg2);
+}
+#endif
+
unsigned long KSTK_ESP(struct task_struct *task)
{
return task_pt_regs(task)->sp;
diff --git a/arch/x86/um/Makefile b/arch/x86/um/Makefile
index e7e7055a8658..69f0827d5f53 100644
--- a/arch/x86/um/Makefile
+++ b/arch/x86/um/Makefile
@@ -16,7 +16,7 @@ obj-y = bug.o bugs_$(BITS).o delay.o fault.o ldt.o \

ifeq ($(CONFIG_X86_32),y)

-obj-y += checksum_32.o
+obj-y += checksum_32.o syscalls_32.o
obj-$(CONFIG_ELF_CORE) += elfcore.o

subarch-y = ../lib/string_32.o ../lib/atomic64_32.o ../lib/atomic64_cx8_32.o
diff --git a/arch/x86/um/syscalls_32.c b/arch/x86/um/syscalls_32.c
new file mode 100644
index 000000000000..627d68836b16
--- /dev/null
+++ b/arch/x86/um/syscalls_32.c
@@ -0,0 +1,7 @@
+#include <linux/syscalls.h>
+#include <os.h>
+
+SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2)
+{
+ return -EINVAL;
+}
diff --git a/include/linux/compat.h b/include/linux/compat.h
index aef47be2a5c1..af9dbc44fd92 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -723,6 +723,8 @@ asmlinkage long compat_sys_sched_rr_get_interval(compat_pid_t pid,
asmlinkage long compat_sys_fanotify_mark(int, unsigned int, __u32, __u32,
int, const char __user *);

+asmlinkage long compat_sys_arch_prctl(int option, unsigned long arg2);
+
/*
* For most but not all architectures, "am I in a compat syscall?" and
* "am I a compat task?" are the same question. For architectures on which
--
2.11.0