[PATCH] x86: pass in pt_regs pointer for syscalls that need it (take 2)

From: Brian Gerst
Date: Wed Feb 11 2009 - 16:44:18 EST

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 take the pointer as an argument instead of relying on
the assumption that the pt_regs structure overlaps the function
arguments.

Signed-off-by: Brian Gerst <brgerst@xxxxxxxxx>
---

v2: drop the regparm(1) usage due to concerns over gcc bugs.

arch/x86/include/asm/syscalls.h | 20 ++++++++++----------
arch/x86/kernel/entry_32.S | 20 ++++++++++++++++++++
arch/x86/kernel/ioport.c | 3 +--
arch/x86/kernel/process_32.c | 32 ++++++++++++++++----------------
arch/x86/kernel/signal.c | 22 ++++------------------
arch/x86/kernel/syscall_table_32.S | 20 ++++++++++----------
arch/x86/kernel/vm86_32.c | 16 ++++++++--------
7 files changed, 69 insertions(+), 64 deletions(-)

diff --git a/arch/x86/include/asm/syscalls.h b/arch/x86/include/asm/syscalls.h
index c0b0bda..77bb31a 100644
--- a/arch/x86/include/asm/syscalls.h
+++ b/arch/x86/include/asm/syscalls.h
@@ -29,21 +29,21 @@ 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);
+int sys_fork(struct pt_regs *);
+int sys_clone(struct pt_regs *);
+int sys_vfork(struct pt_regs *);
+int sys_execve(struct pt_regs *);

/* 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);
+int sys_sigaltstack(struct pt_regs *);
+unsigned long sys_sigreturn(struct pt_regs *);
+int sys_rt_sigreturn(struct pt_regs *);

/* kernel/ioport.c */
-asmlinkage long sys_iopl(unsigned long);
+long sys_iopl(struct pt_regs *);

/* kernel/sys_i386_32.c */
asmlinkage long sys_mmap2(unsigned long, unsigned long, unsigned long,
@@ -59,8 +59,8 @@ 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);
+int sys_vm86old(struct pt_regs *);
+int sys_vm86(struct pt_regs *);

#else /* CONFIG_X86_32 */

diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 5f5bd22..3de7b57 100644
--- 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 b12208f..e41980a 100644
--- a/arch/x86/kernel/ioport.c
+++ b/arch/x86/kernel/ioport.c
@@ -131,9 +131,8 @@ static int do_iopl(unsigned int level, struct pt_regs *regs)
}

#ifdef CONFIG_X86_32
-asmlinkage long sys_iopl(unsigned long regsp)
+long sys_iopl(struct pt_regs *regs)
{
- 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 b50604b..fec79ad 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -603,24 +603,24 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
return prev_p;
}

-asmlinkage int sys_fork(struct pt_regs regs)
+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)
+int sys_clone(struct pt_regs *regs)
{
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;
+ 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 +633,27 @@ 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)
+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)
+int sys_execve(struct pt_regs *regs)
{
int error;
char *filename;

- filename = getname((char __user *) regs.bx);
+ filename = getname((char __user *) regs->bx);
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);
+ (char __user * __user *) regs->cx,
+ (char __user * __user *) regs->dx,
+ 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 8562387..ccfb274 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -549,14 +549,9 @@ 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)
+int sys_sigaltstack(struct pt_regs *regs)
{
- /*
- * 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;
+ const stack_t __user *uss = (const stack_t __user *)regs->bx;
stack_t __user *uoss = (stack_t __user *)regs->cx;

return do_sigaltstack(uss, uoss, regs->sp);
@@ -574,14 +569,12 @@ sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
* Do a signal return; undo the signal stack.
*/
#ifdef CONFIG_X86_32
-asmlinkage unsigned long sys_sigreturn(unsigned long __unused)
+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)))
@@ -640,15 +633,8 @@ 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)
+int sys_rt_sigreturn(struct pt_regs *regs)
{
- struct pt_regs *regs = (struct pt_regs *)&__unused;
-
return do_rt_sigreturn(regs);
}
#else /* !CONFIG_X86_32 */
diff --git a/arch/x86/kernel/syscall_table_32.S b/arch/x86/kernel/syscall_table_32.S
index e2e86a0..3bdb648 100644
--- 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 55ea30d..d7ac84e 100644
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -197,9 +197,9 @@ 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)
+int sys_vm86old(struct pt_regs *regs)
{
- struct vm86_struct __user *v86 = (struct vm86_struct __user *)regs.bx;
+ 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 +218,7 @@ 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 +227,7 @@ out:
}


-asmlinkage int sys_vm86(struct pt_regs regs)
+int sys_vm86(struct pt_regs *regs)
{
struct kernel_vm86_struct info; /* declare this _on top_,
* this avoids wasting of stack space.
@@ -239,12 +239,12 @@ asmlinkage int sys_vm86(struct pt_regs regs)
struct vm86plus_struct __user *v86;

tsk = current;
- switch (regs.bx) {
+ switch (regs->bx) {
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(regs->bx, (int)regs->cx);
goto out;
case VM86_PLUS_INSTALL_CHECK:
/*
@@ -261,14 +261,14 @@ 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 *)regs->cx;
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);
--
1.6.1

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