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x32: Add ptrace for x32

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X32 ptrace is a hybrid of 64bit ptrace and compat ptrace with 32bit
address and longs.  It use 64bit ptrace to access the full 64bit
registers.  PTRACE_PEEKUSR and PTRACE_POKEUSR are only allowed to access
segment and debug registers.  PTRACE_PEEKUSR returns the lower 32bits
and PTRACE_POKEUSR zero-extends 32bit value to 64bit.   It works since
the upper 32bits of segment and debug registers of x32 process are always
zero.  GDB only uses PTRACE_PEEKUSR and PTRACE_POKEUSR to access
segment and debug registers.

[ hpa: changed TIF_X32 test to use !is_ia32_task() instead, and moved
  the system call number to the now-unused 521 slot. ]

Signed-off-by: "H.J. Lu" <hjl.tools@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Link: http://lkml.kernel.org/r/1329696488-16970-1-git-send-email-hpa@zytor.com
This commit is contained in:
H.J. Lu 2012-03-05 15:32:11 -08:00 committed by H. Peter Anvin
parent e7084fd52e
commit 55283e2537
2 changed files with 101 additions and 2 deletions
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99
arch/x86/kernel/ptrace.c
View file

@ -1130,6 +1130,100 @@ static int genregs32_set(struct task_struct *target,
return ret;
}
#ifdef CONFIG_X86_X32_ABI
static long x32_arch_ptrace(struct task_struct *child,
compat_long_t request, compat_ulong_t caddr,
compat_ulong_t cdata)
{
unsigned long addr = caddr;
unsigned long data = cdata;
void __user *datap = compat_ptr(data);
int ret;
switch (request) {
/* Read 32bits at location addr in the USER area. Only allow
to return the lower 32bits of segment and debug registers. */
case PTRACE_PEEKUSR: {
u32 tmp;
ret = -EIO;
if ((addr & (sizeof(data) - 1)) || addr >= sizeof(struct user) ||
addr < offsetof(struct user_regs_struct, cs))
break;
tmp = 0; /* Default return condition */
if (addr < sizeof(struct user_regs_struct))
tmp = getreg(child, addr);
else if (addr >= offsetof(struct user, u_debugreg[0]) &&
addr <= offsetof(struct user, u_debugreg[7])) {
addr -= offsetof(struct user, u_debugreg[0]);
tmp = ptrace_get_debugreg(child, addr / sizeof(data));
}
ret = put_user(tmp, (__u32 __user *)datap);
break;
}
/* Write the word at location addr in the USER area. Only allow
to update segment and debug registers with the upper 32bits
zero-extended. */
case PTRACE_POKEUSR:
ret = -EIO;
if ((addr & (sizeof(data) - 1)) || addr >= sizeof(struct user) ||
addr < offsetof(struct user_regs_struct, cs))
break;
if (addr < sizeof(struct user_regs_struct))
ret = putreg(child, addr, data);
else if (addr >= offsetof(struct user, u_debugreg[0]) &&
addr <= offsetof(struct user, u_debugreg[7])) {
addr -= offsetof(struct user, u_debugreg[0]);
ret = ptrace_set_debugreg(child,
addr / sizeof(data), data);
}
break;
case PTRACE_GETREGS: /* Get all gp regs from the child. */
return copy_regset_to_user(child,
task_user_regset_view(current),
REGSET_GENERAL,
0, sizeof(struct user_regs_struct),
datap);
case PTRACE_SETREGS: /* Set all gp regs in the child. */
return copy_regset_from_user(child,
task_user_regset_view(current),
REGSET_GENERAL,
0, sizeof(struct user_regs_struct),
datap);
case PTRACE_GETFPREGS: /* Get the child FPU state. */
return copy_regset_to_user(child,
task_user_regset_view(current),
REGSET_FP,
0, sizeof(struct user_i387_struct),
datap);
case PTRACE_SETFPREGS: /* Set the child FPU state. */
return copy_regset_from_user(child,
task_user_regset_view(current),
REGSET_FP,
0, sizeof(struct user_i387_struct),
datap);
/* normal 64bit interface to access TLS data.
Works just like arch_prctl, except that the arguments
are reversed. */
case PTRACE_ARCH_PRCTL:
return do_arch_prctl(child, data, addr);
default:
return compat_ptrace_request(child, request, addr, data);
}
return ret;
}
#endif
long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
compat_ulong_t caddr, compat_ulong_t cdata)
{
@ -1139,6 +1233,11 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
int ret;
__u32 val;
#ifdef CONFIG_X86_X32_ABI
if (!is_ia32_task())
return x32_arch_ptrace(child, request, caddr, cdata);
#endif
switch (request) {
case PTRACE_PEEKUSR:
ret = getreg32(child, addr, &val);

4
arch/x86/syscalls/syscall_64.tbl
View file

@ -107,7 +107,7 @@
98 common getrusage sys_getrusage
99 common sysinfo sys_sysinfo
100 common times sys_times
101 common ptrace sys_ptrace
101 64 ptrace sys_ptrace
102 common getuid sys_getuid
103 common syslog sys_syslog
104 common getgid sys_getgid
@ -331,7 +331,7 @@
518 x32 sendmsg compat_sys_sendmsg
519 x32 recvmsg compat_sys_recvmsg
520 x32 execve stub_x32_execve
# 521 available
521 x32 ptrace compat_sys_ptrace
522 x32 rt_sigpending sys32_rt_sigpending
523 x32 rt_sigtimedwait compat_sys_rt_sigtimedwait
524 x32 rt_sigqueueinfo sys32_rt_sigqueueinfo