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arch/tile: provide PT_FLAGS_COMPAT value in pt_regs

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This flag is set for ptrace GETREGS or PEEKUSER for processes
that are COMPAT, i.e. 32-bit.  This allows things like strace
to easily discover what personality to use, for example.

Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
This commit is contained in:
Chris Metcalf 2012-12-12 17:24:39 -05:00
parent 17a263540c
commit cb67e161bc
2 changed files with 46 additions and 17 deletions
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6
arch/tile/include/uapi/asm/ptrace.h
View File

@ -84,5 +84,11 @@ struct pt_regs {
#define PTRACE_O_TRACEMIGRATE 0x00010000
#define PTRACE_EVENT_MIGRATE 16
/*
* Flag bits in pt_regs.flags that are part of the ptrace API.
* We start our numbering higher up to avoid confusion with the
* non-ABI kernel-internal values that use the low 16 bits.
*/
#define PT_FLAGS_COMPAT 0x10000 /* process is an -m32 compat process */
#endif /* _UAPI_ASM_TILE_PTRACE_H */

57
arch/tile/kernel/ptrace.c
View File

@ -45,6 +45,41 @@ void ptrace_disable(struct task_struct *child)
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
}
/*
* Get registers from task and ready the result for userspace.
* Note that we localize the API issues to getregs() and putregs() at
* some cost in performance, e.g. we need a full pt_regs copy for
* PEEKUSR, and two copies for POKEUSR. But in general we expect
* GETREGS/PUTREGS to be the API of choice anyway.
*/
static char *getregs(struct task_struct *child, struct pt_regs *uregs)
{
*uregs = *task_pt_regs(child);
/* Set up flags ABI bits. */
uregs->flags = 0;
#ifdef CONFIG_COMPAT
if (task_thread_info(child)->status & TS_COMPAT)
uregs->flags |= PT_FLAGS_COMPAT;
#endif
return (char *)uregs;
}
/* Put registers back to task. */
static void putregs(struct task_struct *child, struct pt_regs *uregs)
{
struct pt_regs *regs = task_pt_regs(child);
/* Don't allow overwriting the kernel-internal flags word. */
uregs->flags = regs->flags;
/* Only allow setting the ICS bit in the ex1 word. */
uregs->ex1 = PL_ICS_EX1(USER_PL, EX1_ICS(uregs->ex1));
*regs = *uregs;
}
long arch_ptrace(struct task_struct *child, long request,
unsigned long addr, unsigned long data)
{
@ -53,14 +88,13 @@ long arch_ptrace(struct task_struct *child, long request,
long ret = -EIO;
char *childreg;
struct pt_regs copyregs;
int ex1_offset;
switch (request) {
case PTRACE_PEEKUSR: /* Read register from pt_regs. */
if (addr >= PTREGS_SIZE)
break;
childreg = (char *)task_pt_regs(child) + addr;
childreg = getregs(child, &copyregs) + addr;
#ifdef CONFIG_COMPAT
if (is_compat_task()) {
if (addr & (sizeof(compat_long_t)-1))
@ -79,17 +113,7 @@ long arch_ptrace(struct task_struct *child, long request,
case PTRACE_POKEUSR: /* Write register in pt_regs. */
if (addr >= PTREGS_SIZE)
break;
childreg = (char *)task_pt_regs(child) + addr;
/* Guard against overwrites of the privilege level. */
ex1_offset = PTREGS_OFFSET_EX1;
#if defined(CONFIG_COMPAT) && defined(__BIG_ENDIAN)
if (is_compat_task()) /* point at low word */
ex1_offset += sizeof(compat_long_t);
#endif
if (addr == ex1_offset)
data = PL_ICS_EX1(USER_PL, EX1_ICS(data));
childreg = getregs(child, &copyregs) + addr;
#ifdef CONFIG_COMPAT
if (is_compat_task()) {
if (addr & (sizeof(compat_long_t)-1))
@ -102,11 +126,12 @@ long arch_ptrace(struct task_struct *child, long request,
break;
*(long *)childreg = data;
}
putregs(child, &copyregs);
ret = 0;
break;
case PTRACE_GETREGS: /* Get all registers from the child. */
if (copy_to_user(datap, task_pt_regs(child),
if (copy_to_user(datap, getregs(child, &copyregs),
sizeof(struct pt_regs)) == 0) {
ret = 0;
}
@ -115,9 +140,7 @@ long arch_ptrace(struct task_struct *child, long request,
case PTRACE_SETREGS: /* Set all registers in the child. */
if (copy_from_user(&copyregs, datap,
sizeof(struct pt_regs)) == 0) {
copyregs.ex1 =
PL_ICS_EX1(USER_PL, EX1_ICS(copyregs.ex1));
*task_pt_regs(child) = copyregs;
putregs(child, &copyregs);
ret = 0;
}
break;