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xtensa: fix coprocessor part of ptrace_{get,set}xregs 

Layout of coprocessor registers in the elf_xtregs_t and
xtregs_coprocessor_t may be different due to alignment. Thus it is not
always possible to copy data between the xtregs_coprocessor_t structure
and the elf_xtregs_t and get correct values for all registers.
Use a table of offsets and sizes of individual coprocessor register
groups to do coprocessor context copying in the ptrace_getxregs and
ptrace_setxregs.
This fixes incorrect coprocessor register values reading from the user
process by the native gdb on an xtensa core with multiple coprocessors
and registers with high alignment requirements.

Cc: stable@vger.kernel.org
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
This commit is contained in:
Max Filippov 2018-11-26 18:06:01 -08:00
parent 03bc996af0
commit 38a35a78c5
1 changed files with 38 additions and 4 deletions
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42
arch/xtensa/kernel/ptrace.c
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@ -127,12 +127,37 @@ static int ptrace_setregs(struct task_struct *child, void __user *uregs)
}
#if XTENSA_HAVE_COPROCESSORS
#define CP_OFFSETS(cp) \
{ \
.elf_xtregs_offset = offsetof(elf_xtregs_t, cp), \
.ti_offset = offsetof(struct thread_info, xtregs_cp.cp), \
.sz = sizeof(xtregs_ ## cp ## _t), \
}
static const struct {
size_t elf_xtregs_offset;
size_t ti_offset;
size_t sz;
} cp_offsets[] = {
CP_OFFSETS(cp0),
CP_OFFSETS(cp1),
CP_OFFSETS(cp2),
CP_OFFSETS(cp3),
CP_OFFSETS(cp4),
CP_OFFSETS(cp5),
CP_OFFSETS(cp6),
CP_OFFSETS(cp7),
};
#endif
static int ptrace_getxregs(struct task_struct *child, void __user *uregs)
{
struct pt_regs *regs = task_pt_regs(child);
struct thread_info *ti = task_thread_info(child);
elf_xtregs_t __user *xtregs = uregs;
int ret = 0;
int i __maybe_unused;
if (!access_ok(VERIFY_WRITE, uregs, sizeof(elf_xtregs_t)))
return -EIO;
@ -140,8 +165,13 @@ static int ptrace_getxregs(struct task_struct *child, void __user *uregs)
#if XTENSA_HAVE_COPROCESSORS
/* Flush all coprocessor registers to memory. */
coprocessor_flush_all(ti);
ret |= __copy_to_user(&xtregs->cp0, &ti->xtregs_cp,
sizeof(xtregs_coprocessor_t));
for (i = 0; i < ARRAY_SIZE(cp_offsets); ++i)
ret |= __copy_to_user((char __user *)xtregs +
cp_offsets[i].elf_xtregs_offset,
(const char *)ti +
cp_offsets[i].ti_offset,
cp_offsets[i].sz);
#endif
ret |= __copy_to_user(&xtregs->opt, &regs->xtregs_opt,
sizeof(xtregs->opt));
@ -157,6 +187,7 @@ static int ptrace_setxregs(struct task_struct *child, void __user *uregs)
struct pt_regs *regs = task_pt_regs(child);
elf_xtregs_t *xtregs = uregs;
int ret = 0;
int i __maybe_unused;
if (!access_ok(VERIFY_READ, uregs, sizeof(elf_xtregs_t)))
return -EFAULT;
@ -166,8 +197,11 @@ static int ptrace_setxregs(struct task_struct *child, void __user *uregs)
coprocessor_flush_all(ti);
coprocessor_release_all(ti);
ret |= __copy_from_user(&ti->xtregs_cp, &xtregs->cp0,
sizeof(xtregs_coprocessor_t));
for (i = 0; i < ARRAY_SIZE(cp_offsets); ++i)
ret |= __copy_from_user((char *)ti + cp_offsets[i].ti_offset,
(const char __user *)xtregs +
cp_offsets[i].elf_xtregs_offset,
cp_offsets[i].sz);
#endif
ret |= __copy_from_user(&regs->xtregs_opt, &xtregs->opt,
sizeof(xtregs->opt));