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arm64: Better native ptrace support for compat tasks

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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: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Yao Qi <yao.qi@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Catalin Marinas 2015-07-14 16:20:17 +01:00 committed by Will Deacon
parent 0723c05fb7
commit 5d220ff942
1 changed files with 91 additions and 1 deletions
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92
arch/arm64/kernel/ptrace.c
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@ -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;
}