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linux/arch/mips/kernel/ptrace.c
Alex Smith 57c7ea513f MIPS: ptrace: Avoid smp_processor_id() in preemptible code 
ptrace_{get,set}_watch_regs access current_cpu_data to get the watch
register count/masks, which calls smp_processor_id(). However they are
run in preemptible context and therefore trigger warnings like so:

[ 6340.092000] BUG: using smp_processor_id() in preemptible [00000000] code: gdb/367
[ 6340.092000] caller is ptrace_get_watch_regs+0x44/0x220

Since the watch register count/masks should be the same across all
CPUs, use boot_cpu_data instead. Note that this may need to change in
future should a heterogenous system be supported where the count/masks
are not the same across all CPUs (the current code is also incorrect
for this scenario - current_cpu_data here would not necessarily be
correct for the CPU that the target task will execute on).

Signed-off-by: Alex Smith <alex.smith@imgtec.com>
Reviewed-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6879/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-05-28 10:54:41 +02:00

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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1992 Ross Biro
* Copyright (C) Linus Torvalds
* Copyright (C) 1994, 95, 96, 97, 98, 2000 Ralf Baechle
* Copyright (C) 1996 David S. Miller
* Kevin D. Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
* Copyright (C) 1999 MIPS Technologies, Inc.
* Copyright (C) 2000 Ulf Carlsson
*
* At this time Linux/MIPS64 only supports syscall tracing, even for 32-bit
* binaries.
*/
#include <linux/compiler.h>
#include <linux/context_tracking.h>
#include <linux/elf.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/regset.h>
#include <linux/smp.h>
#include <linux/user.h>
#include <linux/security.h>
#include <linux/tracehook.h>
#include <linux/audit.h>
#include <linux/seccomp.h>
#include <linux/ftrace.h>
#include <asm/byteorder.h>
#include <asm/cpu.h>
#include <asm/dsp.h>
#include <asm/fpu.h>
#include <asm/mipsregs.h>
#include <asm/mipsmtregs.h>
#include <asm/pgtable.h>
#include <asm/page.h>
#include <asm/syscall.h>
#include <asm/uaccess.h>
#include <asm/bootinfo.h>
#include <asm/reg.h>
#define CREATE_TRACE_POINTS
#include <trace/events/syscalls.h>
/*
* Called by kernel/ptrace.c when detaching..
*
* Make sure single step bits etc are not set.
*/
void ptrace_disable(struct task_struct *child)
{
/* Don't load the watchpoint registers for the ex-child. */
clear_tsk_thread_flag(child, TIF_LOAD_WATCH);
}
/*
* Read a general register set. We always use the 64-bit format, even
* for 32-bit kernels and for 32-bit processes on a 64-bit kernel.
* Registers are sign extended to fill the available space.
*/
int ptrace_getregs(struct task_struct *child, __s64 __user *data)
{
struct pt_regs *regs;
int i;
if (!access_ok(VERIFY_WRITE, data, 38 * 8))
return -EIO;
regs = task_pt_regs(child);
for (i = 0; i < 32; i++)
__put_user((long)regs->regs[i], data + i);
__put_user((long)regs->lo, data + EF_LO - EF_R0);
__put_user((long)regs->hi, data + EF_HI - EF_R0);
__put_user((long)regs->cp0_epc, data + EF_CP0_EPC - EF_R0);
__put_user((long)regs->cp0_badvaddr, data + EF_CP0_BADVADDR - EF_R0);
__put_user((long)regs->cp0_status, data + EF_CP0_STATUS - EF_R0);
__put_user((long)regs->cp0_cause, data + EF_CP0_CAUSE - EF_R0);
return 0;
}
/*
* Write a general register set. As for PTRACE_GETREGS, we always use
* the 64-bit format. On a 32-bit kernel only the lower order half
* (according to endianness) will be used.
*/
int ptrace_setregs(struct task_struct *child, __s64 __user *data)
{
struct pt_regs *regs;
int i;
if (!access_ok(VERIFY_READ, data, 38 * 8))
return -EIO;
regs = task_pt_regs(child);
for (i = 0; i < 32; i++)
__get_user(regs->regs[i], data + i);
__get_user(regs->lo, data + EF_LO - EF_R0);
__get_user(regs->hi, data + EF_HI - EF_R0);
__get_user(regs->cp0_epc, data + EF_CP0_EPC - EF_R0);
/* badvaddr, status, and cause may not be written. */
return 0;
}
int ptrace_getfpregs(struct task_struct *child, __u32 __user *data)
{
int i;
if (!access_ok(VERIFY_WRITE, data, 33 * 8))
return -EIO;
if (tsk_used_math(child)) {
union fpureg *fregs = get_fpu_regs(child);
for (i = 0; i < 32; i++)
__put_user(get_fpr64(&fregs[i], 0),
i + (__u64 __user *)data);
} else {
for (i = 0; i < 32; i++)
__put_user((__u64) -1, i + (__u64 __user *) data);
}
__put_user(child->thread.fpu.fcr31, data + 64);
__put_user(current_cpu_data.fpu_id, data + 65);
return 0;
}
int ptrace_setfpregs(struct task_struct *child, __u32 __user *data)
{
union fpureg *fregs;
u64 fpr_val;
int i;
if (!access_ok(VERIFY_READ, data, 33 * 8))
return -EIO;
fregs = get_fpu_regs(child);
for (i = 0; i < 32; i++) {
__get_user(fpr_val, i + (__u64 __user *)data);
set_fpr64(&fregs[i], 0, fpr_val);
}
__get_user(child->thread.fpu.fcr31, data + 64);
/* FIR may not be written. */
return 0;
}
int ptrace_get_watch_regs(struct task_struct *child,
struct pt_watch_regs __user *addr)
{
enum pt_watch_style style;
int i;
if (!cpu_has_watch || boot_cpu_data.watch_reg_use_cnt == 0)
return -EIO;
if (!access_ok(VERIFY_WRITE, addr, sizeof(struct pt_watch_regs)))
return -EIO;
#ifdef CONFIG_32BIT
style = pt_watch_style_mips32;
#define WATCH_STYLE mips32
#else
style = pt_watch_style_mips64;
#define WATCH_STYLE mips64
#endif
__put_user(style, &addr->style);
__put_user(boot_cpu_data.watch_reg_use_cnt,
&addr->WATCH_STYLE.num_valid);
for (i = 0; i < boot_cpu_data.watch_reg_use_cnt; i++) {
__put_user(child->thread.watch.mips3264.watchlo[i],
&addr->WATCH_STYLE.watchlo[i]);
__put_user(child->thread.watch.mips3264.watchhi[i] & 0xfff,
&addr->WATCH_STYLE.watchhi[i]);
__put_user(boot_cpu_data.watch_reg_masks[i],
&addr->WATCH_STYLE.watch_masks[i]);
}
for (; i < 8; i++) {
__put_user(0, &addr->WATCH_STYLE.watchlo[i]);
__put_user(0, &addr->WATCH_STYLE.watchhi[i]);
__put_user(0, &addr->WATCH_STYLE.watch_masks[i]);
}
return 0;
}
int ptrace_set_watch_regs(struct task_struct *child,
struct pt_watch_regs __user *addr)
{
int i;
int watch_active = 0;
unsigned long lt[NUM_WATCH_REGS];
u16 ht[NUM_WATCH_REGS];
if (!cpu_has_watch || boot_cpu_data.watch_reg_use_cnt == 0)
return -EIO;
if (!access_ok(VERIFY_READ, addr, sizeof(struct pt_watch_regs)))
return -EIO;
/* Check the values. */
for (i = 0; i < boot_cpu_data.watch_reg_use_cnt; i++) {
__get_user(lt[i], &addr->WATCH_STYLE.watchlo[i]);
#ifdef CONFIG_32BIT
if (lt[i] & __UA_LIMIT)
return -EINVAL;
#else
if (test_tsk_thread_flag(child, TIF_32BIT_ADDR)) {
if (lt[i] & 0xffffffff80000000UL)
return -EINVAL;
} else {
if (lt[i] & __UA_LIMIT)
return -EINVAL;
}
#endif
__get_user(ht[i], &addr->WATCH_STYLE.watchhi[i]);
if (ht[i] & ~0xff8)
return -EINVAL;
}
/* Install them. */
for (i = 0; i < boot_cpu_data.watch_reg_use_cnt; i++) {
if (lt[i] & 7)
watch_active = 1;
child->thread.watch.mips3264.watchlo[i] = lt[i];
/* Set the G bit. */
child->thread.watch.mips3264.watchhi[i] = ht[i];
}
if (watch_active)
set_tsk_thread_flag(child, TIF_LOAD_WATCH);
else
clear_tsk_thread_flag(child, TIF_LOAD_WATCH);
return 0;
}
/* regset get/set implementations */
static int gpr_get(struct task_struct *target,
const struct user_regset *regset,
unsigned int pos, unsigned int count,
void *kbuf, void __user *ubuf)
{
struct pt_regs *regs = task_pt_regs(target);
return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
regs, 0, sizeof(*regs));
}
static int gpr_set(struct task_struct *target,
const struct user_regset *regset,
unsigned int pos, unsigned int count,
const void *kbuf, const void __user *ubuf)
{
struct pt_regs newregs;
int ret;
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
&newregs,
0, sizeof(newregs));
if (ret)
return ret;
*task_pt_regs(target) = newregs;
return 0;
}
static int fpr_get(struct task_struct *target,
const struct user_regset *regset,
unsigned int pos, unsigned int count,
void *kbuf, void __user *ubuf)
{
unsigned i;
int err;
u64 fpr_val;
/* XXX fcr31 */
if (sizeof(target->thread.fpu.fpr[i]) == sizeof(elf_fpreg_t))
return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
&target->thread.fpu,
0, sizeof(elf_fpregset_t));
for (i = 0; i < NUM_FPU_REGS; i++) {
fpr_val = get_fpr64(&target->thread.fpu.fpr[i], 0);
err = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
&fpr_val, i * sizeof(elf_fpreg_t),
(i + 1) * sizeof(elf_fpreg_t));
if (err)
return err;
}
return 0;
}
static int fpr_set(struct task_struct *target,
const struct user_regset *regset,
unsigned int pos, unsigned int count,
const void *kbuf, const void __user *ubuf)
{
unsigned i;
int err;
u64 fpr_val;
/* XXX fcr31 */
if (sizeof(target->thread.fpu.fpr[i]) == sizeof(elf_fpreg_t))
return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
&target->thread.fpu,
0, sizeof(elf_fpregset_t));
for (i = 0; i < NUM_FPU_REGS; i++) {
err = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
&fpr_val, i * sizeof(elf_fpreg_t),
(i + 1) * sizeof(elf_fpreg_t));
if (err)
return err;
set_fpr64(&target->thread.fpu.fpr[i], 0, fpr_val);
}
return 0;
}
enum mips_regset {
REGSET_GPR,
REGSET_FPR,
};
static const struct user_regset mips_regsets[] = {
[REGSET_GPR] = {
.core_note_type = NT_PRSTATUS,
.n = ELF_NGREG,
.size = sizeof(unsigned int),
.align = sizeof(unsigned int),
.get = gpr_get,
.set = gpr_set,
},
[REGSET_FPR] = {
.core_note_type = NT_PRFPREG,
.n = ELF_NFPREG,
.size = sizeof(elf_fpreg_t),
.align = sizeof(elf_fpreg_t),
.get = fpr_get,
.set = fpr_set,
},
};
static const struct user_regset_view user_mips_view = {
.name = "mips",
.e_machine = ELF_ARCH,
.ei_osabi = ELF_OSABI,
.regsets = mips_regsets,
.n = ARRAY_SIZE(mips_regsets),
};
static const struct user_regset mips64_regsets[] = {
[REGSET_GPR] = {
.core_note_type = NT_PRSTATUS,
.n = ELF_NGREG,
.size = sizeof(unsigned long),
.align = sizeof(unsigned long),
.get = gpr_get,
.set = gpr_set,
},
[REGSET_FPR] = {
.core_note_type = NT_PRFPREG,
.n = ELF_NFPREG,
.size = sizeof(elf_fpreg_t),
.align = sizeof(elf_fpreg_t),
.get = fpr_get,
.set = fpr_set,
},
};
static const struct user_regset_view user_mips64_view = {
.name = "mips",
.e_machine = ELF_ARCH,
.ei_osabi = ELF_OSABI,
.regsets = mips64_regsets,
.n = ARRAY_SIZE(mips_regsets),
};
const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
#ifdef CONFIG_32BIT
return &user_mips_view;
#endif
#ifdef CONFIG_MIPS32_O32
if (test_thread_flag(TIF_32BIT_REGS))
return &user_mips_view;
#endif
return &user_mips64_view;
}
long arch_ptrace(struct task_struct *child, long request,
unsigned long addr, unsigned long data)
{
int ret;
void __user *addrp = (void __user *) addr;
void __user *datavp = (void __user *) data;
unsigned long __user *datalp = (void __user *) data;
switch (request) {
/* when I and D space are separate, these will need to be fixed. */
case PTRACE_PEEKTEXT: /* read word at location addr. */
case PTRACE_PEEKDATA:
ret = generic_ptrace_peekdata(child, addr, data);
break;
/* Read the word at location addr in the USER area. */
case PTRACE_PEEKUSR: {
struct pt_regs *regs;
union fpureg *fregs;
unsigned long tmp = 0;
regs = task_pt_regs(child);
ret = 0; /* Default return value. */
switch (addr) {
case 0 ... 31:
tmp = regs->regs[addr];
break;
case FPR_BASE ... FPR_BASE + 31:
if (!tsk_used_math(child)) {
/* FP not yet used */
tmp = -1;
break;
}
fregs = get_fpu_regs(child);
#ifdef CONFIG_32BIT
if (test_thread_flag(TIF_32BIT_FPREGS)) {
/*
* The odd registers are actually the high
* order bits of the values stored in the even
* registers - unless we're using r2k_switch.S.
*/
tmp = get_fpr32(&fregs[(addr & ~1) - FPR_BASE],
addr & 1);
break;
}
#endif
tmp = get_fpr32(&fregs[addr - FPR_BASE], 0);
break;
case PC:
tmp = regs->cp0_epc;
break;
case CAUSE:
tmp = regs->cp0_cause;
break;
case BADVADDR:
tmp = regs->cp0_badvaddr;
break;
case MMHI:
tmp = regs->hi;
break;
case MMLO:
tmp = regs->lo;
break;
#ifdef CONFIG_CPU_HAS_SMARTMIPS
case ACX:
tmp = regs->acx;
break;
#endif
case FPC_CSR:
tmp = child->thread.fpu.fcr31;
break;
case FPC_EIR:
/* implementation / version register */
tmp = current_cpu_data.fpu_id;
break;
case DSP_BASE ... DSP_BASE + 5: {
dspreg_t *dregs;
if (!cpu_has_dsp) {
tmp = 0;
ret = -EIO;
goto out;
}
dregs = __get_dsp_regs(child);
tmp = (unsigned long) (dregs[addr - DSP_BASE]);
break;
}
case DSP_CONTROL:
if (!cpu_has_dsp) {
tmp = 0;
ret = -EIO;
goto out;
}
tmp = child->thread.dsp.dspcontrol;
break;
default:
tmp = 0;
ret = -EIO;
goto out;
}
ret = put_user(tmp, datalp);
break;
}
/* when I and D space are separate, this will have to be fixed. */
case PTRACE_POKETEXT: /* write the word at location addr. */
case PTRACE_POKEDATA:
ret = generic_ptrace_pokedata(child, addr, data);
break;
case PTRACE_POKEUSR: {
struct pt_regs *regs;
ret = 0;
regs = task_pt_regs(child);
switch (addr) {
case 0 ... 31:
regs->regs[addr] = data;
break;
case FPR_BASE ... FPR_BASE + 31: {
union fpureg *fregs = get_fpu_regs(child);
if (!tsk_used_math(child)) {
/* FP not yet used */
memset(&child->thread.fpu, ~0,
sizeof(child->thread.fpu));
child->thread.fpu.fcr31 = 0;
}
#ifdef CONFIG_32BIT
if (test_thread_flag(TIF_32BIT_FPREGS)) {
/*
* The odd registers are actually the high
* order bits of the values stored in the even
* registers - unless we're using r2k_switch.S.
*/
set_fpr32(&fregs[(addr & ~1) - FPR_BASE],
addr & 1, data);
break;
}
#endif
set_fpr64(&fregs[addr - FPR_BASE], 0, data);
break;
}
case PC:
regs->cp0_epc = data;
break;
case MMHI:
regs->hi = data;
break;
case MMLO:
regs->lo = data;
break;
#ifdef CONFIG_CPU_HAS_SMARTMIPS
case ACX:
regs->acx = data;
break;
#endif
case FPC_CSR:
child->thread.fpu.fcr31 = data;
break;
case DSP_BASE ... DSP_BASE + 5: {
dspreg_t *dregs;
if (!cpu_has_dsp) {
ret = -EIO;
break;
}
dregs = __get_dsp_regs(child);
dregs[addr - DSP_BASE] = data;
break;
}
case DSP_CONTROL:
if (!cpu_has_dsp) {
ret = -EIO;
break;
}
child->thread.dsp.dspcontrol = data;
break;
default:
/* The rest are not allowed. */
ret = -EIO;
break;
}
break;
}
case PTRACE_GETREGS:
ret = ptrace_getregs(child, datavp);
break;
case PTRACE_SETREGS:
ret = ptrace_setregs(child, datavp);
break;
case PTRACE_GETFPREGS:
ret = ptrace_getfpregs(child, datavp);
break;
case PTRACE_SETFPREGS:
ret = ptrace_setfpregs(child, datavp);
break;
case PTRACE_GET_THREAD_AREA:
ret = put_user(task_thread_info(child)->tp_value, datalp);
break;
case PTRACE_GET_WATCH_REGS:
ret = ptrace_get_watch_regs(child, addrp);
break;
case PTRACE_SET_WATCH_REGS:
ret = ptrace_set_watch_regs(child, addrp);
break;
default:
ret = ptrace_request(child, request, addr, data);
break;
}
out:
return ret;
}
/*
* Notification of system call entry/exit
* - triggered by current->work.syscall_trace
*/
asmlinkage long syscall_trace_enter(struct pt_regs *regs, long syscall)
{
long ret = 0;
user_exit();
if (secure_computing(syscall) == -1)
return -1;
if (test_thread_flag(TIF_SYSCALL_TRACE) &&
tracehook_report_syscall_entry(regs))
ret = -1;
if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
trace_sys_enter(regs, regs->regs[2]);
audit_syscall_entry(syscall_get_arch(),
syscall,
regs->regs[4], regs->regs[5],
regs->regs[6], regs->regs[7]);
return syscall;
}
/*
* Notification of system call entry/exit
* - triggered by current->work.syscall_trace
*/
asmlinkage void syscall_trace_leave(struct pt_regs *regs)
{
/*
* We may come here right after calling schedule_user()
* or do_notify_resume(), in which case we can be in RCU
* user mode.
*/
user_exit();
audit_syscall_exit(regs);
if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
trace_sys_exit(regs, regs->regs[2]);
if (test_thread_flag(TIF_SYSCALL_TRACE))
tracehook_report_syscall_exit(regs, 0);
user_enter();
}
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