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[Xen-devel] [PATCH v3 1/3] syscalls, x86 Expose arch_prctl on x86-32.



arch_prctl is currently 64-bit only. Wire it up for 32-bits, as a no-op for
now. Rename the second arg to a more generic name.

Signed-off-by: Kyle Huey <khuey@xxxxxxxxxxxx>
---
 arch/x86/entry/syscalls/syscall_32.tbl |  1 +
 arch/x86/include/asm/proto.h           |  5 ++++-
 arch/x86/kernel/process.c              | 10 ++++++++++
 arch/x86/kernel/process_64.c           | 33 +++++++++++++++++++++------------
 arch/x86/kernel/ptrace.c               |  8 ++++----
 arch/x86/um/Makefile                   |  2 +-
 arch/x86/um/syscalls_32.c              |  7 +++++++
 arch/x86/um/syscalls_64.c              |  4 ++--
 include/linux/compat.h                 |  2 ++
 9 files changed, 52 insertions(+), 20 deletions(-)
 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 f848572..666fa61 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -386,3 +386,4 @@
 377    i386    copy_file_range         sys_copy_file_range
 378    i386    preadv2                 sys_preadv2                     
compat_sys_preadv2
 379    i386    pwritev2                sys_pwritev2                    
compat_sys_pwritev2
+380    i386    arch_prctl              compat_sys_arch_prctl           
compat_sys_arch_prctl
diff --git a/arch/x86/include/asm/proto.h b/arch/x86/include/asm/proto.h
index 9b9b30b..f0e86aa 100644
--- a/arch/x86/include/asm/proto.h
+++ b/arch/x86/include/asm/proto.h
@@ -30,6 +30,9 @@ void x86_report_nx(void);
 
 extern int reboot_force;
 
-long do_arch_prctl(struct task_struct *task, int code, unsigned long addr);
+long do_arch_prctl_common(struct task_struct *task, int code, unsigned long 
addr);
+#ifdef CONFIG_X86_64
+long do_arch_prctl_64(struct task_struct *task, int code, unsigned long addr);
+#endif
 
 #endif /* _ASM_X86_PROTO_H */
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 62c0b0e..1421451 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -567,3 +567,13 @@ unsigned long get_wchan(struct task_struct *p)
        } while (count++ < 16 && p->state != TASK_RUNNING);
        return 0;
 }
+
+long do_arch_prctl_common(struct task_struct *task, int code, unsigned long 
arg2)
+{
+       return -EINVAL;
+}
+
+asmlinkage long compat_sys_arch_prctl(int code, unsigned long arg2)
+{
+       return do_arch_prctl_common(current, code, arg2);
+}
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 63236d8..0e44608 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -35,6 +35,7 @@
 #include <linux/uaccess.h>
 #include <linux/io.h>
 #include <linux/ftrace.h>
+#include <linux/syscalls.h>
 
 #include <asm/pgtable.h>
 #include <asm/processor.h>
@@ -196,7 +197,7 @@ int copy_thread_tls(unsigned long clone_flags, unsigned 
long sp,
                                (struct user_desc __user *)tls, 0);
                else
 #endif
-                       err = do_arch_prctl(p, ARCH_SET_FS, tls);
+                       err = do_arch_prctl_64(p, ARCH_SET_FS, tls);
                if (err)
                        goto out;
        }
@@ -524,7 +525,7 @@ void set_personality_ia32(bool x32)
 }
 EXPORT_SYMBOL_GPL(set_personality_ia32);
 
-long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
+long do_arch_prctl_64(struct task_struct *task, int code, unsigned long arg2)
 {
        int ret = 0;
        int doit = task == current;
@@ -532,48 +533,50 @@ long do_arch_prctl(struct task_struct *task, int code, 
unsigned long addr)
 
        switch (code) {
        case ARCH_SET_GS:
-               if (addr >= TASK_SIZE_MAX)
+               if (arg2 >= TASK_SIZE_MAX)
                        return -EPERM;
                cpu = get_cpu();
                task->thread.gsindex = 0;
-               task->thread.gsbase = addr;
+               task->thread.gsbase = arg2;
                if (doit) {
                        load_gs_index(0);
-                       ret = wrmsrl_safe(MSR_KERNEL_GS_BASE, addr);
+                       ret = wrmsrl_safe(MSR_KERNEL_GS_BASE, arg2);
                }
                put_cpu();
                break;
        case ARCH_SET_FS:
                /* Not strictly needed for fs, but do it for symmetry
                   with gs */
-               if (addr >= TASK_SIZE_MAX)
+               if (arg2 >= TASK_SIZE_MAX)
                        return -EPERM;
                cpu = get_cpu();
                task->thread.fsindex = 0;
-               task->thread.fsbase = addr;
+               task->thread.fsbase = arg2;
                if (doit) {
                        /* set the selector to 0 to not confuse __switch_to */
                        loadsegment(fs, 0);
-                       ret = wrmsrl_safe(MSR_FS_BASE, addr);
+                       ret = wrmsrl_safe(MSR_FS_BASE, arg2);
                }
                put_cpu();
                break;
        case ARCH_GET_FS: {
                unsigned long base;
+
                if (doit)
                        rdmsrl(MSR_FS_BASE, base);
                else
                        base = task->thread.fsbase;
-               ret = put_user(base, (unsigned long __user *)addr);
+               ret = put_user(base, (unsigned long __user *)arg2);
                break;
        }
        case ARCH_GET_GS: {
                unsigned long base;
+
                if (doit)
                        rdmsrl(MSR_KERNEL_GS_BASE, base);
                else
                        base = task->thread.gsbase;
-               ret = put_user(base, (unsigned long __user *)addr);
+               ret = put_user(base, (unsigned long __user *)arg2);
                break;
        }
 
@@ -585,9 +588,15 @@ long do_arch_prctl(struct task_struct *task, int code, 
unsigned long addr)
        return ret;
 }
 
-long sys_arch_prctl(int code, unsigned long addr)
+SYSCALL_DEFINE2(arch_prctl, int, code, unsigned long, arg2)
 {
-       return do_arch_prctl(current, code, addr);
+       long ret;
+
+       ret = do_arch_prctl_64(current, code, arg2);
+       if (ret == -EINVAL)
+               ret = do_arch_prctl_common(current, code, arg2);
+
+       return ret;
 }
 
 unsigned long KSTK_ESP(struct task_struct *task)
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index f79576a..030cbc5 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -395,12 +395,12 @@ static int putreg(struct task_struct *child,
                if (value >= TASK_SIZE_MAX)
                        return -EIO;
                /*
-                * When changing the segment base, use do_arch_prctl
+                * When changing the segment base, use do_arch_prctl_64
                 * to set either thread.fs or thread.fsindex and the
                 * corresponding GDT slot.
                 */
                if (child->thread.fsbase != value)
-                       return do_arch_prctl(child, ARCH_SET_FS, value);
+                       return do_arch_prctl_64(child, ARCH_SET_FS, value);
                return 0;
        case offsetof(struct user_regs_struct,gs_base):
                /*
@@ -409,7 +409,7 @@ static int putreg(struct task_struct *child,
                if (value >= TASK_SIZE_MAX)
                        return -EIO;
                if (child->thread.gsbase != value)
-                       return do_arch_prctl(child, ARCH_SET_GS, value);
+                       return do_arch_prctl_64(child, ARCH_SET_GS, value);
                return 0;
 #endif
        }
@@ -868,7 +868,7 @@ long arch_ptrace(struct task_struct *child, long request,
                   Works just like arch_prctl, except that the arguments
                   are reversed. */
        case PTRACE_ARCH_PRCTL:
-               ret = do_arch_prctl(child, data, addr);
+               ret = do_arch_prctl_64(child, data, addr);
                break;
 #endif
 
diff --git a/arch/x86/um/Makefile b/arch/x86/um/Makefile
index 3ee2bb6..5e039d6 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 ksyms.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 0000000..c6812c1
--- /dev/null
+++ b/arch/x86/um/syscalls_32.c
@@ -0,0 +1,7 @@
+#include <linux/syscalls.h>
+#include <os.h>
+
+long compat_sys_arch_prctl(int code, unsigned long arg2)
+{
+       return -EINVAL;
+}
diff --git a/arch/x86/um/syscalls_64.c b/arch/x86/um/syscalls_64.c
index e655227..d0a7160 100644
--- a/arch/x86/um/syscalls_64.c
+++ b/arch/x86/um/syscalls_64.c
@@ -72,9 +72,9 @@ long arch_prctl(struct task_struct *task, int code, unsigned 
long __user *addr)
        return ret;
 }
 
-long sys_arch_prctl(int code, unsigned long addr)
+long sys_arch_prctl(int code, unsigned long arg2)
 {
-       return arch_prctl(current, code, (unsigned long __user *) addr);
+       return arch_prctl(current, code, (unsigned long __user *) arg2);
 }
 
 void arch_switch_to(struct task_struct *to)
diff --git a/include/linux/compat.h b/include/linux/compat.h
index f964ef7..0039d53 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -722,6 +722,8 @@ 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, unsigned long);
+
 /*
  * 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
-- 
2.9.3

base-commit: 4cea8776571b18db7485930cb422faa739580c8c

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