linux/arch/mips/kernel/watch.c
Mathieu Malaterre 69095e3900
mips: annotate implicit fall throughs
There is a plan to build the kernel with -Wimplicit-fallthrough and
these places in the code produced warnings. Fix them up.

This patch produces no change in behaviour, but should be reviewed in
case these are actually bugs not intentional fallthoughs.

Signed-off-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Kees Cook <keescook@google.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
2018-12-03 13:42:38 -08:00

212 lines
5.4 KiB
C

/*
* 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) 2008 David Daney
*/
#include <linux/sched.h>
#include <asm/processor.h>
#include <asm/watch.h>
/*
* Install the watch registers for the current thread. A maximum of
* four registers are installed although the machine may have more.
*/
void mips_install_watch_registers(struct task_struct *t)
{
struct mips3264_watch_reg_state *watches = &t->thread.watch.mips3264;
unsigned int watchhi = MIPS_WATCHHI_G | /* Trap all ASIDs */
MIPS_WATCHHI_IRW; /* Clear result bits */
switch (current_cpu_data.watch_reg_use_cnt) {
default:
BUG();
case 4:
write_c0_watchlo3(watches->watchlo[3]);
write_c0_watchhi3(watchhi | watches->watchhi[3]);
/* fall through */
case 3:
write_c0_watchlo2(watches->watchlo[2]);
write_c0_watchhi2(watchhi | watches->watchhi[2]);
/* fall through */
case 2:
write_c0_watchlo1(watches->watchlo[1]);
write_c0_watchhi1(watchhi | watches->watchhi[1]);
/* fall through */
case 1:
write_c0_watchlo0(watches->watchlo[0]);
write_c0_watchhi0(watchhi | watches->watchhi[0]);
}
}
/*
* Read back the watchhi registers so the user space debugger has
* access to the I, R, and W bits. A maximum of four registers are
* read although the machine may have more.
*/
void mips_read_watch_registers(void)
{
struct mips3264_watch_reg_state *watches =
&current->thread.watch.mips3264;
unsigned int watchhi_mask = MIPS_WATCHHI_MASK | MIPS_WATCHHI_IRW;
switch (current_cpu_data.watch_reg_use_cnt) {
default:
BUG();
case 4:
watches->watchhi[3] = (read_c0_watchhi3() & watchhi_mask);
/* fall through */
case 3:
watches->watchhi[2] = (read_c0_watchhi2() & watchhi_mask);
/* fall through */
case 2:
watches->watchhi[1] = (read_c0_watchhi1() & watchhi_mask);
/* fall through */
case 1:
watches->watchhi[0] = (read_c0_watchhi0() & watchhi_mask);
}
if (current_cpu_data.watch_reg_use_cnt == 1 &&
(watches->watchhi[0] & MIPS_WATCHHI_IRW) == 0) {
/* Pathological case of release 1 architecture that
* doesn't set the condition bits. We assume that
* since we got here, the watch condition was met and
* signal that the conditions requested in watchlo
* were met. */
watches->watchhi[0] |= (watches->watchlo[0] & MIPS_WATCHHI_IRW);
}
}
/*
* Disable all watch registers. Although only four registers are
* installed, all are cleared to eliminate the possibility of endless
* looping in the watch handler.
*/
void mips_clear_watch_registers(void)
{
switch (current_cpu_data.watch_reg_count) {
default:
BUG();
case 8:
write_c0_watchlo7(0);
/* fall through */
case 7:
write_c0_watchlo6(0);
/* fall through */
case 6:
write_c0_watchlo5(0);
/* fall through */
case 5:
write_c0_watchlo4(0);
/* fall through */
case 4:
write_c0_watchlo3(0);
/* fall through */
case 3:
write_c0_watchlo2(0);
/* fall through */
case 2:
write_c0_watchlo1(0);
/* fall through */
case 1:
write_c0_watchlo0(0);
}
}
void mips_probe_watch_registers(struct cpuinfo_mips *c)
{
unsigned int t;
if ((c->options & MIPS_CPU_WATCH) == 0)
return;
/*
* Check which of the I,R and W bits are supported, then
* disable the register.
*/
write_c0_watchlo0(MIPS_WATCHLO_IRW);
back_to_back_c0_hazard();
t = read_c0_watchlo0();
write_c0_watchlo0(0);
c->watch_reg_masks[0] = t & MIPS_WATCHLO_IRW;
/* Write the mask bits and read them back to determine which
* can be used. */
c->watch_reg_count = 1;
c->watch_reg_use_cnt = 1;
t = read_c0_watchhi0();
write_c0_watchhi0(t | MIPS_WATCHHI_MASK);
back_to_back_c0_hazard();
t = read_c0_watchhi0();
c->watch_reg_masks[0] |= (t & MIPS_WATCHHI_MASK);
if ((t & MIPS_WATCHHI_M) == 0)
return;
write_c0_watchlo1(MIPS_WATCHLO_IRW);
back_to_back_c0_hazard();
t = read_c0_watchlo1();
write_c0_watchlo1(0);
c->watch_reg_masks[1] = t & MIPS_WATCHLO_IRW;
c->watch_reg_count = 2;
c->watch_reg_use_cnt = 2;
t = read_c0_watchhi1();
write_c0_watchhi1(t | MIPS_WATCHHI_MASK);
back_to_back_c0_hazard();
t = read_c0_watchhi1();
c->watch_reg_masks[1] |= (t & MIPS_WATCHHI_MASK);
if ((t & MIPS_WATCHHI_M) == 0)
return;
write_c0_watchlo2(MIPS_WATCHLO_IRW);
back_to_back_c0_hazard();
t = read_c0_watchlo2();
write_c0_watchlo2(0);
c->watch_reg_masks[2] = t & MIPS_WATCHLO_IRW;
c->watch_reg_count = 3;
c->watch_reg_use_cnt = 3;
t = read_c0_watchhi2();
write_c0_watchhi2(t | MIPS_WATCHHI_MASK);
back_to_back_c0_hazard();
t = read_c0_watchhi2();
c->watch_reg_masks[2] |= (t & MIPS_WATCHHI_MASK);
if ((t & MIPS_WATCHHI_M) == 0)
return;
write_c0_watchlo3(MIPS_WATCHLO_IRW);
back_to_back_c0_hazard();
t = read_c0_watchlo3();
write_c0_watchlo3(0);
c->watch_reg_masks[3] = t & MIPS_WATCHLO_IRW;
c->watch_reg_count = 4;
c->watch_reg_use_cnt = 4;
t = read_c0_watchhi3();
write_c0_watchhi3(t | MIPS_WATCHHI_MASK);
back_to_back_c0_hazard();
t = read_c0_watchhi3();
c->watch_reg_masks[3] |= (t & MIPS_WATCHHI_MASK);
if ((t & MIPS_WATCHHI_M) == 0)
return;
/* We use at most 4, but probe and report up to 8. */
c->watch_reg_count = 5;
t = read_c0_watchhi4();
if ((t & MIPS_WATCHHI_M) == 0)
return;
c->watch_reg_count = 6;
t = read_c0_watchhi5();
if ((t & MIPS_WATCHHI_M) == 0)
return;
c->watch_reg_count = 7;
t = read_c0_watchhi6();
if ((t & MIPS_WATCHHI_M) == 0)
return;
c->watch_reg_count = 8;
}