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Diffstat (limited to 'arch/powerpc/xmon/xmon.c')
-rw-r--r--arch/powerpc/xmon/xmon.c121
1 files changed, 94 insertions, 27 deletions
diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index d83364ebc5c5..a7056049709e 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -25,6 +25,7 @@
#include <linux/nmi.h>
#include <linux/ctype.h>
#include <linux/highmem.h>
+#include <linux/security.h>
#include <asm/debugfs.h>
#include <asm/ptrace.h>
@@ -187,6 +188,8 @@ static void dump_tlb_44x(void);
static void dump_tlb_book3e(void);
#endif
+static void clear_all_bpt(void);
+
#ifdef CONFIG_PPC64
#define REG "%.16lx"
#else
@@ -283,10 +286,38 @@ Commands:\n\
" U show uptime information\n"
" ? help\n"
" # n limit output to n lines per page (for dp, dpa, dl)\n"
-" zr reboot\n\
- zh halt\n"
+" zr reboot\n"
+" zh halt\n"
;
+#ifdef CONFIG_SECURITY
+static bool xmon_is_locked_down(void)
+{
+ static bool lockdown;
+
+ if (!lockdown) {
+ lockdown = !!security_locked_down(LOCKDOWN_XMON_RW);
+ if (lockdown) {
+ printf("xmon: Disabled due to kernel lockdown\n");
+ xmon_is_ro = true;
+ }
+ }
+
+ if (!xmon_is_ro) {
+ xmon_is_ro = !!security_locked_down(LOCKDOWN_XMON_WR);
+ if (xmon_is_ro)
+ printf("xmon: Read-only due to kernel lockdown\n");
+ }
+
+ return lockdown;
+}
+#else /* CONFIG_SECURITY */
+static inline bool xmon_is_locked_down(void)
+{
+ return false;
+}
+#endif
+
static struct pt_regs *xmon_regs;
static inline void sync(void)
@@ -438,7 +469,10 @@ static bool wait_for_other_cpus(int ncpus)
return false;
}
-#endif /* CONFIG_SMP */
+#else /* CONFIG_SMP */
+static inline void get_output_lock(void) {}
+static inline void release_output_lock(void) {}
+#endif
static inline int unrecoverable_excp(struct pt_regs *regs)
{
@@ -455,6 +489,7 @@ static int xmon_core(struct pt_regs *regs, int fromipi)
int cmd = 0;
struct bpt *bp;
long recurse_jmp[JMP_BUF_LEN];
+ bool locked_down;
unsigned long offset;
unsigned long flags;
#ifdef CONFIG_SMP
@@ -465,6 +500,8 @@ static int xmon_core(struct pt_regs *regs, int fromipi)
local_irq_save(flags);
hard_irq_disable();
+ locked_down = xmon_is_locked_down();
+
if (!fromipi) {
tracing_enabled = tracing_is_on();
tracing_off();
@@ -518,7 +555,8 @@ static int xmon_core(struct pt_regs *regs, int fromipi)
if (!fromipi) {
get_output_lock();
- excprint(regs);
+ if (!locked_down)
+ excprint(regs);
if (bp) {
printf("cpu 0x%x stopped at breakpoint 0x%tx (",
cpu, BP_NUM(bp));
@@ -570,10 +608,14 @@ static int xmon_core(struct pt_regs *regs, int fromipi)
}
remove_bpts();
disable_surveillance();
- /* for breakpoint or single step, print the current instr. */
- if (bp || TRAP(regs) == 0xd00)
- ppc_inst_dump(regs->nip, 1, 0);
- printf("enter ? for help\n");
+
+ if (!locked_down) {
+ /* for breakpoint or single step, print curr insn */
+ if (bp || TRAP(regs) == 0xd00)
+ ppc_inst_dump(regs->nip, 1, 0);
+ printf("enter ? for help\n");
+ }
+
mb();
xmon_gate = 1;
barrier();
@@ -597,8 +639,9 @@ static int xmon_core(struct pt_regs *regs, int fromipi)
spin_cpu_relax();
touch_nmi_watchdog();
} else {
- cmd = cmds(regs);
- if (cmd != 0) {
+ if (!locked_down)
+ cmd = cmds(regs);
+ if (locked_down || cmd != 0) {
/* exiting xmon */
insert_bpts();
xmon_gate = 0;
@@ -635,13 +678,16 @@ static int xmon_core(struct pt_regs *regs, int fromipi)
"can't continue\n");
remove_bpts();
disable_surveillance();
- /* for breakpoint or single step, print the current instr. */
- if (bp || TRAP(regs) == 0xd00)
- ppc_inst_dump(regs->nip, 1, 0);
- printf("enter ? for help\n");
+ if (!locked_down) {
+ /* for breakpoint or single step, print current insn */
+ if (bp || TRAP(regs) == 0xd00)
+ ppc_inst_dump(regs->nip, 1, 0);
+ printf("enter ? for help\n");
+ }
}
- cmd = cmds(regs);
+ if (!locked_down)
+ cmd = cmds(regs);
insert_bpts();
in_xmon = 0;
@@ -670,7 +716,10 @@ static int xmon_core(struct pt_regs *regs, int fromipi)
}
}
#endif
- insert_cpu_bpts();
+ if (locked_down)
+ clear_all_bpt();
+ else
+ insert_cpu_bpts();
touch_nmi_watchdog();
local_irq_restore(flags);
@@ -884,7 +933,7 @@ static void insert_cpu_bpts(void)
if (dabr.enabled) {
brk.address = dabr.address;
brk.type = (dabr.enabled & HW_BRK_TYPE_DABR) | HW_BRK_TYPE_PRIV_ALL;
- brk.len = 8;
+ brk.len = DABR_MAX_LEN;
__set_breakpoint(&brk);
}
@@ -1047,10 +1096,6 @@ cmds(struct pt_regs *excp)
set_lpp_cmd();
break;
case 'b':
- if (xmon_is_ro) {
- printf(xmon_ro_msg);
- break;
- }
bpt_cmds();
break;
case 'C':
@@ -1319,11 +1364,16 @@ bpt_cmds(void)
struct bpt *bp;
cmd = inchar();
+
switch (cmd) {
#ifndef CONFIG_PPC_8xx
static const char badaddr[] = "Only kernel addresses are permitted for breakpoints\n";
int mode;
case 'd': /* bd - hardware data breakpoint */
+ if (xmon_is_ro) {
+ printf(xmon_ro_msg);
+ break;
+ }
if (!ppc_breakpoint_available()) {
printf("Hardware data breakpoint not supported on this cpu\n");
break;
@@ -1351,6 +1401,10 @@ bpt_cmds(void)
break;
case 'i': /* bi - hardware instr breakpoint */
+ if (xmon_is_ro) {
+ printf(xmon_ro_msg);
+ break;
+ }
if (!cpu_has_feature(CPU_FTR_ARCH_207S)) {
printf("Hardware instruction breakpoint "
"not supported on this cpu\n");
@@ -1409,7 +1463,8 @@ bpt_cmds(void)
break;
}
termch = cmd;
- if (!scanhex(&a)) {
+
+ if (xmon_is_ro || !scanhex(&a)) {
/* print all breakpoints */
printf(" type address\n");
if (dabr.enabled) {
@@ -3762,6 +3817,11 @@ static void xmon_init(int enable)
#ifdef CONFIG_MAGIC_SYSRQ
static void sysrq_handle_xmon(int key)
{
+ if (xmon_is_locked_down()) {
+ clear_all_bpt();
+ xmon_init(0);
+ return;
+ }
/* ensure xmon is enabled */
xmon_init(1);
debugger(get_irq_regs());
@@ -3783,7 +3843,6 @@ static int __init setup_xmon_sysrq(void)
device_initcall(setup_xmon_sysrq);
#endif /* CONFIG_MAGIC_SYSRQ */
-#ifdef CONFIG_DEBUG_FS
static void clear_all_bpt(void)
{
int i;
@@ -3801,18 +3860,22 @@ static void clear_all_bpt(void)
iabr = NULL;
dabr.enabled = 0;
}
-
- printf("xmon: All breakpoints cleared\n");
}
+#ifdef CONFIG_DEBUG_FS
static int xmon_dbgfs_set(void *data, u64 val)
{
xmon_on = !!val;
xmon_init(xmon_on);
/* make sure all breakpoints removed when disabling */
- if (!xmon_on)
+ if (!xmon_on) {
clear_all_bpt();
+ get_output_lock();
+ printf("xmon: All breakpoints cleared\n");
+ release_output_lock();
+ }
+
return 0;
}
@@ -3838,7 +3901,11 @@ static int xmon_early __initdata;
static int __init early_parse_xmon(char *p)
{
- if (!p || strncmp(p, "early", 5) == 0) {
+ if (xmon_is_locked_down()) {
+ xmon_init(0);
+ xmon_early = 0;
+ xmon_on = 0;
+ } else if (!p || strncmp(p, "early", 5) == 0) {
/* just "xmon" is equivalent to "xmon=early" */
xmon_init(1);
xmon_early = 1;
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.