Commit 5d220ff9 authored by Catalin Marinas's avatar Catalin Marinas Committed by Will Deacon
Browse files

arm64: Better native ptrace support for compat tasks 



The compat ptrace interface allows access to the TLS register, hardware
breakpoints and watchpoints, syscall number. However, a native task
using the native ptrace interface to debug compat tasks (e.g. multi-arch
gdb) only has access to the general and VFP register sets. The compat
ptrace interface cannot be accessed from a native task.

This patch adds a new user_aarch32_ptrace_view which contains the TLS,
hardware breakpoint/watchpoint and syscall number regsets in addition to
the existing GPR and VFP regsets. This view is backwards compatible with
the previous kernels. Core dumping of 32-bit tasks and compat ptrace are
not affected since the original user_aarch32_view is preserved.

Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Reported-by: default avatarYao Qi <yao.qi@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 0723c05f

arch/arm64/kernel/ptrace.c

+91 −1
Original line number Diff line number Diff line
@@ -826,6 +826,30 @@ static int compat_vfp_set(struct task_struct *target, 
	return ret;

}



static int compat_tls_get(struct task_struct *target,

			  const struct user_regset *regset, unsigned int pos,

			  unsigned int count, void *kbuf, void __user *ubuf)

{

	compat_ulong_t tls = (compat_ulong_t)target->thread.tp_value;

	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, &tls, 0, -1);

}



static int compat_tls_set(struct task_struct *target,

			  const struct user_regset *regset, unsigned int pos,

			  unsigned int count, const void *kbuf,

			  const void __user *ubuf)

{

	int ret;

	compat_ulong_t tls;



	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &tls, 0, -1);

	if (ret)

		return ret;



	target->thread.tp_value = tls;

	return ret;

}



static const struct user_regset aarch32_regsets[] = {

	[REGSET_COMPAT_GPR] = {

		.core_note_type = NT_PRSTATUS,
@@ -850,6 +874,64 @@ static const struct user_regset_view user_aarch32_view = { 
	.regsets = aarch32_regsets, .n = ARRAY_SIZE(aarch32_regsets)

};



static const struct user_regset aarch32_ptrace_regsets[] = {

	[REGSET_GPR] = {

		.core_note_type = NT_PRSTATUS,

		.n = COMPAT_ELF_NGREG,

		.size = sizeof(compat_elf_greg_t),

		.align = sizeof(compat_elf_greg_t),

		.get = compat_gpr_get,

		.set = compat_gpr_set

	},

	[REGSET_FPR] = {

		.core_note_type = NT_ARM_VFP,

		.n = VFP_STATE_SIZE / sizeof(compat_ulong_t),

		.size = sizeof(compat_ulong_t),

		.align = sizeof(compat_ulong_t),

		.get = compat_vfp_get,

		.set = compat_vfp_set

	},

	[REGSET_TLS] = {

		.core_note_type = NT_ARM_TLS,

		.n = 1,

		.size = sizeof(compat_ulong_t),

		.align = sizeof(compat_ulong_t),

		.get = compat_tls_get,

		.set = compat_tls_set,

	},

#ifdef CONFIG_HAVE_HW_BREAKPOINT

	[REGSET_HW_BREAK] = {

		.core_note_type = NT_ARM_HW_BREAK,

		.n = sizeof(struct user_hwdebug_state) / sizeof(u32),

		.size = sizeof(u32),

		.align = sizeof(u32),

		.get = hw_break_get,

		.set = hw_break_set,

	},

	[REGSET_HW_WATCH] = {

		.core_note_type = NT_ARM_HW_WATCH,

		.n = sizeof(struct user_hwdebug_state) / sizeof(u32),

		.size = sizeof(u32),

		.align = sizeof(u32),

		.get = hw_break_get,

		.set = hw_break_set,

	},

#endif

	[REGSET_SYSTEM_CALL] = {

		.core_note_type = NT_ARM_SYSTEM_CALL,

		.n = 1,

		.size = sizeof(int),

		.align = sizeof(int),

		.get = system_call_get,

		.set = system_call_set,

	},

};



static const struct user_regset_view user_aarch32_ptrace_view = {

	.name = "aarch32", .e_machine = EM_ARM,

	.regsets = aarch32_ptrace_regsets, .n = ARRAY_SIZE(aarch32_ptrace_regsets)

};



static int compat_ptrace_read_user(struct task_struct *tsk, compat_ulong_t off,

				   compat_ulong_t __user *ret)

{
@@ -1109,8 +1191,16 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request, 
const struct user_regset_view *task_user_regset_view(struct task_struct *task)

{

#ifdef CONFIG_COMPAT

	if (is_compat_thread(task_thread_info(task)))

	/*

	 * Core dumping of 32-bit tasks or compat ptrace requests must use the

	 * user_aarch32_view compatible with arm32. Native ptrace requests on

	 * 32-bit children use an extended user_aarch32_ptrace_view to allow

	 * access to the TLS register.

	 */

	if (is_compat_task())

		return &user_aarch32_view;

	else if (is_compat_thread(task_thread_info(task)))

		return &user_aarch32_ptrace_view;

#endif

	return &user_aarch64_view;

}

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