x86, um/x86: switch to generic sys_execve and kernel_execve

32bit wrapper is lost on that; 64bit one is *not*, since
we need to arrange for full pt_regs on stack when we call
sys_execve() and we need to load callee-saved ones from
there afterwards.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

17 files changed, 34 insertions, 158 deletions

diff --git a/arch/um/kernel/exec.c b/arch/um/kernel/exec.c
index 8c82786da823..e427301f55d6 100644
--- a/arch/um/kernel/exec.c
+++ b/arch/um/kernel/exec.c
@@ -16,7 +16,6 @@
 #include "mem_user.h"
 #include "skas.h"
 #include "os.h"
-#include "internal.h"
 
 void flush_thread(void)
 {
@@ -49,27 +48,7 @@ void start_thread(struct pt_regs *regs, unsigned long eip, unsigned long esp)
 }
 EXPORT_SYMBOL(start_thread);
 
-long um_execve(const char *file, const char __user *const __user *argv, const char __user *const __user *env)
+void __noreturn ret_from_kernel_execve(struct pt_regs *unused)
 {
-        long err;
-
-        err = do_execve(file, argv, env, &current->thread.regs);
-        if (!err)
-                UML_LONGJMP(current->thread.exec_buf, 1);
-        return err;
-}
-
-long sys_execve(const char __user *file, const char __user *const __user *argv,
-                const char __user *const __user *env)
-{
-        long error;
-        char *filename;
-
-        filename = getname(file);
-        error = PTR_ERR(filename);
-        if (IS_ERR(filename)) goto out;
-        error = do_execve(filename, argv, env, &current->thread.regs);
-        putname(filename);
- out:
-        return error;
+        UML_LONGJMP(current->thread.exec_buf, 1);
 }
diff --git a/arch/um/kernel/internal.h b/arch/um/kernel/internal.h
deleted file mode 100644
index 5bf97db24a04..000000000000
--- a/arch/um/kernel/internal.h
+++ /dev/null
@@ -1 +0,0 @@
-extern long um_execve(const char *file, const char __user *const __user *argv, const char __user *const __user *env);
diff --git a/arch/um/kernel/syscall.c b/arch/um/kernel/syscall.c
index a4c6d8eee74c..a5639c472772 100644
--- a/arch/um/kernel/syscall.c
+++ b/arch/um/kernel/syscall.c
@@ -13,7 +13,6 @@
 #include "asm/mman.h"
 #include "asm/uaccess.h"
 #include "asm/unistd.h"
-#include "internal.h"
 
 long sys_fork(void)
 {
@@ -50,19 +49,3 @@ long old_mmap(unsigned long addr, unsigned long len,
  out:
         return err;
 }
-
-int kernel_execve(const char *filename,
-                  const char *const argv[],
-                  const char *const envp[])
-{
-        mm_segment_t fs;
-        int ret;
-
-        fs = get_fs();
-        set_fs(KERNEL_DS);
-        ret = um_execve(filename, (const char __user *const __user *)argv,
-                        (const char __user *const __user *) envp);
-        set_fs(fs);
-
-        return ret;
-}
diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S
index 20e5f7ba0e6b..e75f941bd2b2 100644
--- a/arch/x86/ia32/ia32entry.S
+++ b/arch/x86/ia32/ia32entry.S
@@ -459,7 +459,7 @@ GLOBAL(\label)
         PTREGSCALL stub32_rt_sigreturn, sys32_rt_sigreturn, %rdi
         PTREGSCALL stub32_sigreturn, sys32_sigreturn, %rdi
         PTREGSCALL stub32_sigaltstack, sys32_sigaltstack, %rdx
-        PTREGSCALL stub32_execve, sys32_execve, %rcx
+        PTREGSCALL stub32_execve, compat_sys_execve, %rcx
         PTREGSCALL stub32_fork, sys_fork, %rdi
         PTREGSCALL stub32_clone, sys32_clone, %rdx
         PTREGSCALL stub32_vfork, sys_vfork, %rdi
diff --git a/arch/x86/ia32/sys_ia32.c b/arch/x86/ia32/sys_ia32.c
index 4540bece0946..6b31144589d0 100644
--- a/arch/x86/ia32/sys_ia32.c
+++ b/arch/x86/ia32/sys_ia32.c
@@ -385,21 +385,6 @@ asmlinkage long sys32_sendfile(int out_fd, int in_fd,
         return ret;
 }
 
-asmlinkage long sys32_execve(const char __user *name, compat_uptr_t __user *argv,
-                             compat_uptr_t __user *envp, struct pt_regs *regs)
-{
-        long error;
-        char *filename;
-
-        filename = getname(name);
-        error = PTR_ERR(filename);
-        if (IS_ERR(filename))
-                return error;
-        error = compat_do_execve(filename, argv, envp, regs);
-        putname(filename);
-        return error;
-}
-
 asmlinkage long sys32_clone(unsigned int clone_flags, unsigned int newsp,
                             struct pt_regs *regs)
 {
diff --git a/arch/x86/include/asm/sys_ia32.h b/arch/x86/include/asm/sys_ia32.h
index 3fda9db48819..1ac127f41fe6 100644
--- a/arch/x86/include/asm/sys_ia32.h
+++ b/arch/x86/include/asm/sys_ia32.h
@@ -54,8 +54,6 @@ asmlinkage long sys32_pwrite(unsigned int, const char __user *, u32, u32, u32);
 asmlinkage long sys32_personality(unsigned long);
 asmlinkage long sys32_sendfile(int, int, compat_off_t __user *, s32);
 
-asmlinkage long sys32_execve(const char __user *, compat_uptr_t __user *,
-                             compat_uptr_t __user *, struct pt_regs *);
 asmlinkage long sys32_clone(unsigned int, unsigned int, struct pt_regs *);
 
 long sys32_lseek(unsigned int, int, unsigned int);
diff --git a/arch/x86/include/asm/syscalls.h b/arch/x86/include/asm/syscalls.h
index f1d8b441fc77..2be0b880417e 100644
--- a/arch/x86/include/asm/syscalls.h
+++ b/arch/x86/include/asm/syscalls.h
@@ -25,7 +25,7 @@ int sys_fork(struct pt_regs *);
 int sys_vfork(struct pt_regs *);
 long sys_execve(const char __user *,
                 const char __user *const __user *,
-                const char __user *const __user *, struct pt_regs *);
+                const char __user *const __user *);
 long sys_clone(unsigned long, unsigned long, void __user *,
                void __user *, struct pt_regs *);
 
diff --git a/arch/x86/include/asm/unistd.h b/arch/x86/include/asm/unistd.h
index 0d9776e9e2dc..55d155560fdf 100644
--- a/arch/x86/include/asm/unistd.h
+++ b/arch/x86/include/asm/unistd.h
@@ -50,6 +50,8 @@
 # define __ARCH_WANT_SYS_TIME
 # define __ARCH_WANT_SYS_UTIME
 # define __ARCH_WANT_SYS_WAITPID
+# define __ARCH_WANT_SYS_EXECVE
+# define __ARCH_WANT_KERNEL_EXECVE
 
 /*
  * "Conditional" syscalls
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 8215e5652d97..566100002233 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -23,7 +23,7 @@ obj-y			+= time.o ioport.o ldt.o dumpstack.o nmi.o
 obj-y                   += setup.o x86_init.o i8259.o irqinit.o jump_label.o
 obj-$(CONFIG_IRQ_WORK)  += irq_work.o
 obj-y                   += probe_roms.o
-obj-$(CONFIG_X86_32)    += sys_i386_32.o i386_ksyms_32.o
+obj-$(CONFIG_X86_32)    += i386_ksyms_32.o
 obj-$(CONFIG_X86_64)    += sys_x86_64.o x8664_ksyms_64.o
 obj-y                   += syscall_$(BITS).o
 obj-$(CONFIG_X86_64)    += vsyscall_64.o
diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
index 68de2dc962ec..28610822fb3c 100644
--- a/arch/x86/kernel/asm-offsets.c
+++ b/arch/x86/kernel/asm-offsets.c
@@ -69,4 +69,7 @@ void common(void) {
         OFFSET(BP_kernel_alignment, boot_params, hdr.kernel_alignment);
         OFFSET(BP_pref_address, boot_params, hdr.pref_address);
         OFFSET(BP_code32_start, boot_params, hdr.code32_start);
+
+        BLANK();
+        DEFINE(PTREGS_SIZE, sizeof(struct pt_regs));
 }
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index ac1107346fc9..b6bb69239296 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -298,6 +298,13 @@ ENTRY(ret_from_fork)
         CFI_ENDPROC
 END(ret_from_fork)
 
+ENTRY(ret_from_kernel_execve)
+        movl %eax, %esp
+        movl $0,PT_EAX(%esp)
+        GET_THREAD_INFO(%ebp)
+        jmp syscall_exit
+END(ret_from_kernel_execve)
+
 /*
  * Interrupt exit functions should be protected against kprobes
  */
@@ -322,8 +329,7 @@ ret_from_intr:
         andl $(X86_EFLAGS_VM | SEGMENT_RPL_MASK), %eax
 #else
         /*
-         * We can be coming here from a syscall done in the kernel space,
-         * e.g. a failed kernel_execve().
+         * We can be coming here from child spawned by kernel_thread().
          */
         movl PT_CS(%esp), %eax
         andl $SEGMENT_RPL_MASK, %eax
@@ -727,7 +733,6 @@ ENDPROC(ptregs_##name)
 PTREGSCALL1(iopl)
 PTREGSCALL0(fork)
 PTREGSCALL0(vfork)
-PTREGSCALL3(execve)
 PTREGSCALL2(sigaltstack)
 PTREGSCALL0(sigreturn)
 PTREGSCALL0(rt_sigreturn)
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 5526d17db676..053c9552ffd9 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -767,7 +767,6 @@ ENTRY(stub_execve)
         PARTIAL_FRAME 0
         SAVE_REST
         FIXUP_TOP_OF_STACK %r11
-        movq %rsp, %rcx
         call sys_execve
         RESTORE_TOP_OF_STACK %r11
         movq %rax,RAX(%rsp)
@@ -817,8 +816,7 @@ ENTRY(stub_x32_execve)
         PARTIAL_FRAME 0
         SAVE_REST
         FIXUP_TOP_OF_STACK %r11
-        movq %rsp, %rcx
-        call sys32_execve
+        call compat_sys_execve
         RESTORE_TOP_OF_STACK %r11
         movq %rax,RAX(%rsp)
         RESTORE_REST
@@ -1216,36 +1214,19 @@ bad_gs:
         jmp  2b
         .previous
 
-/*
- * execve(). This function needs to use IRET, not SYSRET, to set up all state properly.
- *
- * C extern interface:
- *       extern long execve(const char *name, char **argv, char **envp)
- *
- * asm input arguments:
- *      rdi: name, rsi: argv, rdx: envp
- *
- * We want to fallback into:
- *      extern long sys_execve(const char *name, char **argv,char **envp, struct pt_regs *regs)
- *
- * do_sys_execve asm fallback arguments:
- *      rdi: name, rsi: argv, rdx: envp, rcx: fake frame on the stack
- */
-ENTRY(kernel_execve)
-        CFI_STARTPROC
-        FAKE_STACK_FRAME $0
-        SAVE_ALL
-        movq %rsp,%rcx
-        call sys_execve
-        movq %rax, RAX(%rsp)
-        RESTORE_REST
-        testq %rax,%rax
-        je int_ret_from_sys_call
-        RESTORE_ARGS
-        UNFAKE_STACK_FRAME
-        ret
-        CFI_ENDPROC
-END(kernel_execve)
+ENTRY(ret_from_kernel_execve)
+        movq %rdi, %rsp
+        movl $0, RAX(%rsp)
+        // RESTORE_REST
+        movq 0*8(%rsp), %r15
+        movq 1*8(%rsp), %r14
+        movq 2*8(%rsp), %r13
+        movq 3*8(%rsp), %r12
+        movq 4*8(%rsp), %rbp
+        movq 5*8(%rsp), %rbx
+        addq $(6*8), %rsp
+        jmp int_ret_from_sys_call
+END(ret_from_kernel_execve)
 
 /* Call softirq on interrupt stack. Interrupts are off. */
 ENTRY(call_softirq)
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 6947ec968bf8..eae2dd5cd5a0 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -299,25 +299,6 @@ sys_clone(unsigned long clone_flags, unsigned long newsp,
 }
 
 /*
- * sys_execve() executes a new program.
- */
-long sys_execve(const char __user *name,
-                const char __user *const __user *argv,
-                const char __user *const __user *envp, struct pt_regs *regs)
-{
-        long error;
-        char *filename;
-
-        filename = getname(name);
-        error = PTR_ERR(filename);
-        if (IS_ERR(filename))
-                return error;
-        error = do_execve(filename, argv, envp, regs);
-        putname(filename);
-        return error;
-}
-
-/*
  * Idle related variables and functions
  */
 unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index c9939875d267..25e7e9390d26 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -207,6 +207,7 @@ start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
         regs->cs                = __USER_CS;
         regs->ip                = new_ip;
         regs->sp                = new_sp;
+        regs->flags             = X86_EFLAGS_IF;
         /*
          * Free the old FP and other extended state
          */
diff --git a/arch/x86/kernel/sys_i386_32.c b/arch/x86/kernel/sys_i386_32.c
deleted file mode 100644
index 0b0cb5fede19..000000000000
--- a/arch/x86/kernel/sys_i386_32.c
+++ /dev/null
@@ -1,40 +0,0 @@
-/*
- * This file contains various random system calls that
- * have a non-standard calling sequence on the Linux/i386
- * platform.
- */
-
-#include <linux/errno.h>
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/fs.h>
-#include <linux/smp.h>
-#include <linux/sem.h>
-#include <linux/msg.h>
-#include <linux/shm.h>
-#include <linux/stat.h>
-#include <linux/syscalls.h>
-#include <linux/mman.h>
-#include <linux/file.h>
-#include <linux/utsname.h>
-#include <linux/ipc.h>
-
-#include <linux/uaccess.h>
-#include <linux/unistd.h>
-
-#include <asm/syscalls.h>
-
-/*
- * Do a system call from kernel instead of calling sys_execve so we
- * end up with proper pt_regs.
- */
-int kernel_execve(const char *filename,
-                  const char *const argv[],
-                  const char *const envp[])
-{
-        long __res;
-        asm volatile ("int $0x80"
-        : "=a" (__res)
-        : "0" (__NR_execve), "b" (filename), "c" (argv), "d" (envp) : "memory");
-        return __res;
-}
diff --git a/arch/x86/syscalls/syscall_32.tbl b/arch/x86/syscalls/syscall_32.tbl
index 7a35a6e71d44..a47103fbc692 100644
--- a/arch/x86/syscalls/syscall_32.tbl
+++ b/arch/x86/syscalls/syscall_32.tbl
@@ -17,7 +17,7 @@
 8       i386    creat                   sys_creat
 9       i386    link                    sys_link
 10      i386    unlink                  sys_unlink
-11      i386    execve                  ptregs_execve                   stub32_execve
+11      i386    execve                  sys_execve                      stub32_execve
 12      i386    chdir                   sys_chdir
 13      i386    time                    sys_time                        compat_sys_time
 14      i386    mknod                   sys_mknod
diff --git a/arch/x86/um/sys_call_table_32.c b/arch/x86/um/sys_call_table_32.c
index b5408cecac6c..232e60504b3a 100644
--- a/arch/x86/um/sys_call_table_32.c
+++ b/arch/x86/um/sys_call_table_32.c
@@ -25,7 +25,6 @@
 #define old_mmap sys_old_mmap
 
 #define ptregs_fork sys_fork
-#define ptregs_execve sys_execve
 #define ptregs_iopl sys_iopl
 #define ptregs_vm86old sys_vm86old
 #define ptregs_clone i386_clone