Commit 55283e25 authored by H.J. Lu's avatar H.J. Lu Committed by H. Peter Anvin
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x32: Add ptrace for x32 



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: default avatar"H.J. Lu" <hjl.tools@gmail.com>
Signed-off-by: default avatarH. 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
parent e7084fd5

arch/x86/kernel/ptrace.c

+99 −0
Original line number Diff line number Diff line
@@ -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);

arch/x86/syscalls/syscall_64.tbl

+2 −2
Original line number Diff line number Diff line
@@ -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

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