[patch 07/37] UML - use correct register file size everywhere

Greg KH
2007-03-30T21:11:11Z

[-- Attachment #1: uml-use-correct-register-file-size-everywhere.patch --]
[-- Type: text/plain, Size: 5092 bytes --]

-stable review patch. If anyone has any objections, please let us know.

------------------
From: Jeff Dike <jdike@addtoit.com>

This patch uses MAX_REG_NR consistently to refer to the register file
size. FRAME_SIZE isn't sufficient because on x86_64, it is smaller
than the ptrace register file size. MAX_REG_NR was introduced as a
consistent way to get the number of registers, but wasn't used
everywhere it should be.

When this causes a problem, it makes PTRACE_SETREGS fail on x86_64
because of a corrupted segment register value in the known-good
register file. The patch also adds a register dump at that point in
case there are any future problems here.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
arch/um/include/sysdep-x86_64/ptrace.h | 4 ----
arch/um/os-Linux/skas/mem.c | 10 +++++++---
arch/um/os-Linux/skas/process.c | 6 +++---
arch/um/os-Linux/sys-i386/registers.c | 5 +++--
arch/um/os-Linux/sys-x86_64/registers.c | 4 ++--
5 files changed, 15 insertions(+), 14 deletions(-)

--- a/arch/um/include/sysdep-x86_64/ptrace.h
+++ b/arch/um/include/sysdep-x86_64/ptrace.h
@@ -104,10 +104,6 @@ union uml_pt_regs {
#endif
#ifdef UML_CONFIG_MODE_SKAS
struct skas_regs {
- /* x86_64 ptrace uses sizeof(user_regs_struct) as its register
- * file size, while i386 uses FRAME_SIZE. Therefore, we need
- * to use UM_FRAME_SIZE here instead of HOST_FRAME_SIZE.
- */
unsigned long regs[MAX_REG_NR];
unsigned long fp[HOST_FP_SIZE];
struct faultinfo faultinfo;
--- a/arch/um/os-Linux/skas/mem.c
+++ b/arch/um/os-Linux/skas/mem.c
@@ -48,7 +48,7 @@ int multi_op_count = 0;
static inline long do_syscall_stub(struct mm_id * mm_idp, void **addr)
{
unsigned long regs[MAX_REG_NR];
- int n;
+ int n, i;
long ret, offset;
unsigned long * data;
unsigned long * syscall;
@@ -66,9 +66,13 @@ static inline long do_syscall_stub(struc
(unsigned long) &__syscall_stub_start);

n = ptrace_setregs(pid, regs);
- if(n < 0)
+ if(n < 0){
+ printk("Registers - \n");
+ for(i = 0; i < MAX_REG_NR; i++)
+ printk("\t%d\t0x%lx\n", i, regs[i]);
panic("do_syscall_stub : PTRACE_SETREGS failed, errno = %d\n",
- n);
+ -n);
+ }

wait_stub_done(pid, 0, "do_syscall_stub");

--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -67,7 +67,7 @@ void wait_stub_done(int pid, int sig, ch

if((n < 0) || !WIFSTOPPED(status) ||
(WSTOPSIG(status) != SIGUSR1 && WSTOPSIG(status) != SIGTRAP)){
- unsigned long regs[HOST_FRAME_SIZE];
+ unsigned long regs[MAX_REG_NR];

if(ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
printk("Failed to get registers from stub, "
@@ -76,7 +76,7 @@ void wait_stub_done(int pid, int sig, ch
int i;

printk("Stub registers -\n");
- for(i = 0; i < HOST_FRAME_SIZE; i++)
+ for(i = 0; i < ARRAY_SIZE(regs); i++)
printk("\t%d - %lx\n", i, regs[i]);
}
panic("%s : failed to wait for SIGUSR1/SIGTRAP, "
@@ -328,7 +328,7 @@ void userspace(union uml_pt_regs *regs)
int copy_context_skas0(unsigned long new_stack, int pid)
{
int err;
- unsigned long regs[HOST_FRAME_SIZE];
+ unsigned long regs[MAX_REG_NR];
unsigned long fp_regs[HOST_FP_SIZE];
unsigned long current_stack = current_stub_stack();
struct stub_data *data = (struct stub_data *) current_stack;
--- a/arch/um/os-Linux/sys-i386/registers.c
+++ b/arch/um/os-Linux/sys-i386/registers.c
@@ -15,7 +15,7 @@

/* These are set once at boot time and not changed thereafter */

-static unsigned long exec_regs[HOST_FRAME_SIZE];
+static unsigned long exec_regs[MAX_REG_NR];
static unsigned long exec_fp_regs[HOST_FP_SIZE];
static unsigned long exec_fpx_regs[HOST_XFP_SIZE];
static int have_fpx_regs = 1;
@@ -101,6 +101,7 @@ void init_registers(int pid)
{
int err;

+ memset(exec_regs, 0, sizeof(exec_regs));
err = ptrace(PTRACE_GETREGS, pid, 0, exec_regs);
if(err)
panic("check_ptrace : PTRACE_GETREGS failed, errno = %d",
@@ -124,7 +125,7 @@ void init_registers(int pid)

void get_safe_registers(unsigned long *regs, unsigned long *fp_regs)
{
- memcpy(regs, exec_regs, HOST_FRAME_SIZE * sizeof(unsigned long));
+ memcpy(regs, exec_regs, sizeof(exec_regs));
if(fp_regs != NULL)
memcpy(fp_regs, exec_fp_regs,
HOST_FP_SIZE * sizeof(unsigned long));
--- a/arch/um/os-Linux/sys-x86_64/registers.c
+++ b/arch/um/os-Linux/sys-x86_64/registers.c
@@ -14,7 +14,7 @@

/* These are set once at boot time and not changed thereafter */

-static unsigned long exec_regs[HOST_FRAME_SIZE];
+static unsigned long exec_regs[MAX_REG_NR];
static unsigned long exec_fp_regs[HOST_FP_SIZE];

void init_thread_registers(union uml_pt_regs *to)
@@ -72,7 +72,7 @@ void init_registers(int pid)

void get_safe_registers(unsigned long *regs, unsigned long *fp_regs)
{
- memcpy(regs, exec_regs, HOST_FRAME_SIZE * sizeof(unsigned long));
+ memcpy(regs, exec_regs, sizeof(exec_regs));
if(fp_regs != NULL)
memcpy(fp_regs, exec_fp_regs,
HOST_FP_SIZE * sizeof(unsigned long));

--