x86: pass in pt_regs pointer for syscalls that need it

Some syscalls need to access the pt_regs structure, either to copy
user register state or to modifiy it.  This patch adds stubs to load
the address of the pt_regs struct into the %eax register, and changes
the syscalls to regparm(1) to receive the pt_regs pointer as the
first argument.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/include/asm/linkage.h b/arch/x86/include/asm/linkage.h
index 5d98d0b68ffc8e08e07cf829ed15103f6fc09796..2fd5926fb97d668ef65b25980fc944142f33e4ce 100644 (file)
--- a/arch/x86/include/asm/linkage.h
+++ b/arch/x86/include/asm/linkage.h
@@ -17,6 +17,13 @@
  */
 #define asmregparm __attribute__((regparm(3)))
 
+/*
+ * For syscalls that need a pointer to the pt_regs struct (ie. fork).
+ * The regs pointer is passed in %eax as the first argument.  The
+ * remaining function arguments remain on the stack.
+ */
+#define ptregscall __attribute__((regparm(1)))
+
 /*
  * Make sure the compiler doesn't do anything stupid with the
  * arguments on the stack - they are owned by the *caller*, not

diff --git a/arch/x86/include/asm/syscalls.h b/arch/x86/include/asm/syscalls.h
index c0b0bda754eeece404b25e3fbe206e790abc87de..617295255a17c5b9e794ab231fd16ce48049ca9e 100644 (file)
--- a/arch/x86/include/asm/syscalls.h
+++ b/arch/x86/include/asm/syscalls.h
@@ -29,21 +29,26 @@ asmlinkage int sys_get_thread_area(struct user_desc __user *);
 /* X86_32 only */
 #ifdef CONFIG_X86_32
 /* kernel/process_32.c */
-asmlinkage int sys_fork(struct pt_regs);
-asmlinkage int sys_clone(struct pt_regs);
-asmlinkage int sys_vfork(struct pt_regs);
-asmlinkage int sys_execve(struct pt_regs);
+ptregscall int sys_fork(struct pt_regs *);
+ptregscall int sys_clone(struct pt_regs *, unsigned long,
+                        unsigned long, int __user *,
+                        unsigned long, int __user *);
+ptregscall int sys_vfork(struct pt_regs *);
+ptregscall int sys_execve(struct pt_regs *, char __user *,
+                         char __user * __user *,
+                         char __user * __user *);
 
 /* kernel/signal_32.c */
 asmlinkage int sys_sigsuspend(int, int, old_sigset_t);
 asmlinkage int sys_sigaction(int, const struct old_sigaction __user *,
                             struct old_sigaction __user *);
-asmlinkage int sys_sigaltstack(unsigned long);
-asmlinkage unsigned long sys_sigreturn(unsigned long);
-asmlinkage int sys_rt_sigreturn(unsigned long);
+ptregscall int sys_sigaltstack(struct pt_regs *, const stack_t __user *,
+                              stack_t __user *);
+ptregscall unsigned long sys_sigreturn(struct pt_regs *);
+ptregscall int sys_rt_sigreturn(struct pt_regs *);
 
 /* kernel/ioport.c */
-asmlinkage long sys_iopl(unsigned long);
+ptregscall long sys_iopl(struct pt_regs *, unsigned int);
 
 /* kernel/sys_i386_32.c */
 asmlinkage long sys_mmap2(unsigned long, unsigned long, unsigned long,
@@ -59,8 +64,8 @@ struct oldold_utsname;
 asmlinkage int sys_olduname(struct oldold_utsname __user *);
 
 /* kernel/vm86_32.c */
-asmlinkage int sys_vm86old(struct pt_regs);
-asmlinkage int sys_vm86(struct pt_regs);
+ptregscall int sys_vm86old(struct pt_regs *, struct vm86_struct __user *);
+ptregscall int sys_vm86(struct pt_regs *, unsigned long, unsigned long);
 
 #else /* CONFIG_X86_32 */
 

diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 5f5bd22adcd471a13d2f83775317c1c77714368b..3de7b5710dc8a004ca5329aec21ba2d3dc60ebc7 100644 (file)
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -697,6 +697,26 @@ syscall_badsys:
 END(syscall_badsys)
        CFI_ENDPROC
 
+/*
+ * System calls that need a pt_regs pointer.
+ */
+#define PTREGSCALL(name) \
+       ALIGN; \
+ptregs_##name: \
+       leal 4(%esp),%eax; \
+       jmp sys_##name;
+
+PTREGSCALL(iopl)
+PTREGSCALL(fork)
+PTREGSCALL(clone)
+PTREGSCALL(vfork)
+PTREGSCALL(execve)
+PTREGSCALL(sigaltstack)
+PTREGSCALL(sigreturn)
+PTREGSCALL(rt_sigreturn)
+PTREGSCALL(vm86)
+PTREGSCALL(vm86old)
+
 .macro FIXUP_ESPFIX_STACK
        /* since we are on a wrong stack, we cant make it a C code :( */
        PER_CPU(gdt_page, %ebx)

diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c
index b12208f4dfee80cbe208c29149aeceafed394f38..7ec148646312f2b13807043af2368e6d770f60d4 100644 (file)
--- a/arch/x86/kernel/ioport.c
+++ b/arch/x86/kernel/ioport.c
@@ -131,10 +131,8 @@ static int do_iopl(unsigned int level, struct pt_regs *regs)
 }
 
 #ifdef CONFIG_X86_32
-asmlinkage long sys_iopl(unsigned long regsp)
+ptregscall long sys_iopl(struct pt_regs *regs, unsigned int level)
 {
-       struct pt_regs *regs = (struct pt_regs *)&regsp;
-       unsigned int level = regs->bx;
        struct thread_struct *t = &current->thread;
        int rc;
 

diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index b50604bb1e41818cd3779b3da5cafcebbee1ec04..5a9dcfb01f7136722d39782804b29274b7f774e2 100644 (file)
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -603,24 +603,18 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
        return prev_p;
 }
 
-asmlinkage int sys_fork(struct pt_regs regs)
+ptregscall int sys_fork(struct pt_regs *regs)
 {
-       return do_fork(SIGCHLD, regs.sp, &regs, 0, NULL, NULL);
+       return do_fork(SIGCHLD, regs->sp, regs, 0, NULL, NULL);
 }
 
-asmlinkage int sys_clone(struct pt_regs regs)
+ptregscall int sys_clone(struct pt_regs *regs, unsigned long clone_flags,
+                        unsigned long newsp, int __user *parent_tidptr,
+                        unsigned long unused, int __user *child_tidptr)
 {
-       unsigned long clone_flags;
-       unsigned long newsp;
-       int __user *parent_tidptr, *child_tidptr;
-
-       clone_flags = regs.bx;
-       newsp = regs.cx;
-       parent_tidptr = (int __user *)regs.dx;
-       child_tidptr = (int __user *)regs.di;
        if (!newsp)
-               newsp = regs.sp;
-       return do_fork(clone_flags, newsp, &regs, 0, parent_tidptr, child_tidptr);
+               newsp = regs->sp;
+       return do_fork(clone_flags, newsp, regs, 0, parent_tidptr, child_tidptr);
 }
 
 /*
@@ -633,27 +627,26 @@ asmlinkage int sys_clone(struct pt_regs regs)
  * do not have enough call-clobbered registers to hold all
  * the information you need.
  */
-asmlinkage int sys_vfork(struct pt_regs regs)
+ptregscall int sys_vfork(struct pt_regs *regs)
 {
-       return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.sp, &regs, 0, NULL, NULL);
+       return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->sp, regs, 0, NULL, NULL);
 }
 
 /*
  * sys_execve() executes a new program.
  */
-asmlinkage int sys_execve(struct pt_regs regs)
+ptregscall int sys_execve(struct pt_regs *regs, char __user *u_filename,
+                         char __user * __user *argv,
+                         char __user * __user *envp)
 {
        int error;
        char *filename;
 
-       filename = getname((char __user *) regs.bx);
+       filename = getname(u_filename);
        error = PTR_ERR(filename);
        if (IS_ERR(filename))
                goto out;
-       error = do_execve(filename,
-                       (char __user * __user *) regs.cx,
-                       (char __user * __user *) regs.dx,
-                       &regs);
+       error = do_execve(filename, argv, envp, regs);
        if (error == 0) {
                /* Make sure we don't return using sysenter.. */
                set_thread_flag(TIF_IRET);

diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 8562387c75a712f98fb6ed6e63cc31d475147775..d7a158367e3866dbce6dbff59414c8b7e3372ea6 100644 (file)
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -549,39 +549,28 @@ sys_sigaction(int sig, const struct old_sigaction __user *act,
 #endif /* CONFIG_X86_32 */
 
 #ifdef CONFIG_X86_32
-asmlinkage int sys_sigaltstack(unsigned long bx)
-{
-       /*
-        * This is needed to make gcc realize it doesn't own the
-        * "struct pt_regs"
-        */
-       struct pt_regs *regs = (struct pt_regs *)&bx;
-       const stack_t __user *uss = (const stack_t __user *)bx;
-       stack_t __user *uoss = (stack_t __user *)regs->cx;
-
-       return do_sigaltstack(uss, uoss, regs->sp);
-}
+ptregscall int
+sys_sigaltstack(struct pt_regs *regs, const stack_t __user *uss,
+               stack_t __user *uoss)
 #else /* !CONFIG_X86_32 */
 asmlinkage long
 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
                struct pt_regs *regs)
+#endif /* CONFIG_X86_32 */
 {
        return do_sigaltstack(uss, uoss, regs->sp);
 }
-#endif /* CONFIG_X86_32 */
 
 /*
  * Do a signal return; undo the signal stack.
  */
 #ifdef CONFIG_X86_32
-asmlinkage unsigned long sys_sigreturn(unsigned long __unused)
+ptregscall unsigned long sys_sigreturn(struct pt_regs *regs)
 {
        struct sigframe __user *frame;
-       struct pt_regs *regs;
        unsigned long ax;
        sigset_t set;
 
-       regs = (struct pt_regs *) &__unused;
        frame = (struct sigframe __user *)(regs->sp - 8);
 
        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
@@ -640,23 +629,13 @@ badframe:
 }
 
 #ifdef CONFIG_X86_32
-/*
- * Note: do not pass in pt_regs directly as with tail-call optimization
- * GCC will incorrectly stomp on the caller's frame and corrupt user-space
- * register state:
- */
-asmlinkage int sys_rt_sigreturn(unsigned long __unused)
-{
-       struct pt_regs *regs = (struct pt_regs *)&__unused;
-
-       return do_rt_sigreturn(regs);
-}
+ptregscall int sys_rt_sigreturn(struct pt_regs *regs)
 #else /* !CONFIG_X86_32 */
 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
+#endif /* CONFIG_X86_32 */
 {
        return do_rt_sigreturn(regs);
 }
-#endif /* CONFIG_X86_32 */
 
 /*
  * OK, we're invoking a handler:

diff --git a/arch/x86/kernel/syscall_table_32.S b/arch/x86/kernel/syscall_table_32.S
index e2e86a08f31d29a52fb116ba8d3befcc2424d8ae..3bdb64829b82718f42bafed884f55d1dbe9e65a2 100644 (file)
--- a/arch/x86/kernel/syscall_table_32.S
+++ b/arch/x86/kernel/syscall_table_32.S
@@ -1,7 +1,7 @@
 ENTRY(sys_call_table)
        .long sys_restart_syscall       /* 0 - old "setup()" system call, used for restarting */
        .long sys_exit
-       .long sys_fork
+       .long ptregs_fork
        .long sys_read
        .long sys_write
        .long sys_open          /* 5 */
@@ -10,7 +10,7 @@ ENTRY(sys_call_table)
        .long sys_creat
        .long sys_link
        .long sys_unlink        /* 10 */
-       .long sys_execve
+       .long ptregs_execve
        .long sys_chdir
        .long sys_time
        .long sys_mknod
@@ -109,17 +109,17 @@ ENTRY(sys_call_table)
        .long sys_newlstat
        .long sys_newfstat
        .long sys_uname
-       .long sys_iopl          /* 110 */
+       .long ptregs_iopl       /* 110 */
        .long sys_vhangup
        .long sys_ni_syscall    /* old "idle" system call */
-       .long sys_vm86old
+       .long ptregs_vm86old
        .long sys_wait4
        .long sys_swapoff       /* 115 */
        .long sys_sysinfo
        .long sys_ipc
        .long sys_fsync
-       .long sys_sigreturn
-       .long sys_clone         /* 120 */
+       .long ptregs_sigreturn
+       .long ptregs_clone      /* 120 */
        .long sys_setdomainname
        .long sys_newuname
        .long sys_modify_ldt
@@ -165,14 +165,14 @@ ENTRY(sys_call_table)
        .long sys_mremap
        .long sys_setresuid16
        .long sys_getresuid16   /* 165 */
-       .long sys_vm86
+       .long ptregs_vm86
        .long sys_ni_syscall    /* Old sys_query_module */
        .long sys_poll
        .long sys_nfsservctl
        .long sys_setresgid16   /* 170 */
        .long sys_getresgid16
        .long sys_prctl
-       .long sys_rt_sigreturn
+       .long ptregs_rt_sigreturn
        .long sys_rt_sigaction
        .long sys_rt_sigprocmask        /* 175 */
        .long sys_rt_sigpending
@@ -185,11 +185,11 @@ ENTRY(sys_call_table)
        .long sys_getcwd
        .long sys_capget
        .long sys_capset        /* 185 */
-       .long sys_sigaltstack
+       .long ptregs_sigaltstack
        .long sys_sendfile
        .long sys_ni_syscall    /* reserved for streams1 */
        .long sys_ni_syscall    /* reserved for streams2 */
-       .long sys_vfork         /* 190 */
+       .long ptregs_vfork      /* 190 */
        .long sys_getrlimit
        .long sys_mmap2
        .long sys_truncate64

diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index 55ea30d2a3d68e8f1061d6a2d4349e0c3f1e9576..8fa6ba7c923326d10ce5fda2502164bc4b7eb3ea 100644 (file)
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -197,9 +197,8 @@ out:
 static int do_vm86_irq_handling(int subfunction, int irqnumber);
 static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk);
 
-asmlinkage int sys_vm86old(struct pt_regs regs)
+ptregscall int sys_vm86old(struct pt_regs *regs, struct vm86_struct __user *v86)
 {
-       struct vm86_struct __user *v86 = (struct vm86_struct __user *)regs.bx;
        struct kernel_vm86_struct info; /* declare this _on top_,
                                         * this avoids wasting of stack space.
                                         * This remains on the stack until we
@@ -218,7 +217,7 @@ asmlinkage int sys_vm86old(struct pt_regs regs)
        if (tmp)
                goto out;
        memset(&info.vm86plus, 0, (int)&info.regs32 - (int)&info.vm86plus);
-       info.regs32 = &regs;
+       info.regs32 = regs;
        tsk->thread.vm86_info = v86;
        do_sys_vm86(&info, tsk);
        ret = 0;        /* we never return here */
@@ -227,7 +226,7 @@ out:
 }
 
 
-asmlinkage int sys_vm86(struct pt_regs regs)
+ptregscall int sys_vm86(struct pt_regs *regs, unsigned long cmd, unsigned long arg)
 {
        struct kernel_vm86_struct info; /* declare this _on top_,
                                         * this avoids wasting of stack space.
@@ -239,12 +238,12 @@ asmlinkage int sys_vm86(struct pt_regs regs)
        struct vm86plus_struct __user *v86;
 
        tsk = current;
-       switch (regs.bx) {
+       switch (cmd) {
        case VM86_REQUEST_IRQ:
        case VM86_FREE_IRQ:
        case VM86_GET_IRQ_BITS:
        case VM86_GET_AND_RESET_IRQ:
-               ret = do_vm86_irq_handling(regs.bx, (int)regs.cx);
+               ret = do_vm86_irq_handling(cmd, (int)arg);
                goto out;
        case VM86_PLUS_INSTALL_CHECK:
                /*
@@ -261,14 +260,14 @@ asmlinkage int sys_vm86(struct pt_regs regs)
        ret = -EPERM;
        if (tsk->thread.saved_sp0)
                goto out;
-       v86 = (struct vm86plus_struct __user *)regs.cx;
+       v86 = (struct vm86plus_struct __user *)arg;
        tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs,
                                       offsetof(struct kernel_vm86_struct, regs32) -
                                       sizeof(info.regs));
        ret = -EFAULT;
        if (tmp)
                goto out;
-       info.regs32 = &regs;
+       info.regs32 = regs;
        info.vm86plus.is_vm86pus = 1;
        tsk->thread.vm86_info = (struct vm86_struct __user *)v86;
        do_sys_vm86(&info, tsk);