[PATCH v14 05/10] arm64: Blacklist non-kprobe-able symbol

From: David Long
Date: Sun Jun 26 2016 - 23:09:20 EST

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From: Pratyush Anand <panand@xxxxxxxxxx>

Add all function symbols which are called from do_debug_exception under
NOKPROBE_SYMBOL, as they can not kprobed.

Signed-off-by: Pratyush Anand <panand@xxxxxxxxxx>
---
arch/arm64/kernel/arm64ksyms.c | 2 ++
arch/arm64/kernel/debug-monitors.c | 17 +++++++++++++++++
arch/arm64/kernel/hw_breakpoint.c | 8 ++++++++
arch/arm64/kernel/kgdb.c | 4 ++++
4 files changed, 31 insertions(+)

diff --git a/arch/arm64/kernel/arm64ksyms.c b/arch/arm64/kernel/arm64ksyms.c
index 678f30b0..b96ff1a 100644
--- a/arch/arm64/kernel/arm64ksyms.c
+++ b/arch/arm64/kernel/arm64ksyms.c
@@ -27,6 +27,7 @@
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/arm-smccc.h>
+#include <linux/kprobes.h>

#include <asm/checksum.h>

@@ -68,6 +69,7 @@ EXPORT_SYMBOL(test_and_change_bit);

#ifdef CONFIG_FUNCTION_TRACER
EXPORT_SYMBOL(_mcount);
+NOKPROBE_SYMBOL(_mcount);
#endif

/* arm-smccc */
diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
index 395de61..2fbc1b9 100644
--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -49,6 +49,7 @@ static void mdscr_write(u32 mdscr)
asm volatile("msr mdscr_el1, %0" :: "r" (mdscr));
local_dbg_restore(flags);
}
+NOKPROBE_SYMBOL(mdscr_write);

static u32 mdscr_read(void)
{
@@ -56,6 +57,7 @@ static u32 mdscr_read(void)
asm volatile("mrs %0, mdscr_el1" : "=r" (mdscr));
return mdscr;
}
+NOKPROBE_SYMBOL(mdscr_read);

/*
* Allow root to disable self-hosted debug from userspace.
@@ -104,6 +106,7 @@ void enable_debug_monitors(enum dbg_active_el el)
mdscr_write(mdscr);
}
}
+NOKPROBE_SYMBOL(enable_debug_monitors);

void disable_debug_monitors(enum dbg_active_el el)
{
@@ -124,6 +127,7 @@ void disable_debug_monitors(enum dbg_active_el el)
mdscr_write(mdscr);
}
}
+NOKPROBE_SYMBOL(disable_debug_monitors);

/*
* OS lock clearing.
@@ -174,6 +178,7 @@ static void set_regs_spsr_ss(struct pt_regs *regs)
spsr |= DBG_SPSR_SS;
regs->pstate = spsr;
}
+NOKPROBE_SYMBOL(set_regs_spsr_ss);

static void clear_regs_spsr_ss(struct pt_regs *regs)
{
@@ -183,6 +188,7 @@ static void clear_regs_spsr_ss(struct pt_regs *regs)
spsr &= ~DBG_SPSR_SS;
regs->pstate = spsr;
}
+NOKPROBE_SYMBOL(clear_regs_spsr_ss);

/* EL1 Single Step Handler hooks */
static LIST_HEAD(step_hook);
@@ -226,6 +232,7 @@ static int call_step_hook(struct pt_regs *regs, unsigned int esr)

return retval;
}
+NOKPROBE_SYMBOL(call_step_hook);

static void send_user_sigtrap(int si_code)
{
@@ -284,6 +291,7 @@ static int single_step_handler(unsigned long addr, unsigned int esr,

return 0;
}
+NOKPROBE_SYMBOL(single_step_handler);

/*
* Breakpoint handler is re-entrant as another breakpoint can
@@ -321,6 +329,7 @@ static int call_break_hook(struct pt_regs *regs, unsigned int esr)

return fn ? fn(regs, esr) : DBG_HOOK_ERROR;
}
+NOKPROBE_SYMBOL(call_break_hook);

static int brk_handler(unsigned long addr, unsigned int esr,
struct pt_regs *regs)
@@ -341,6 +350,7 @@ static int brk_handler(unsigned long addr, unsigned int esr,

return 0;
}
+NOKPROBE_SYMBOL(brk_handler);

int aarch32_break_handler(struct pt_regs *regs)
{
@@ -377,6 +387,7 @@ int aarch32_break_handler(struct pt_regs *regs)
send_user_sigtrap(TRAP_BRKPT);
return 0;
}
+NOKPROBE_SYMBOL(aarch32_break_handler);

static int __init debug_traps_init(void)
{
@@ -398,6 +409,7 @@ void user_rewind_single_step(struct task_struct *task)
if (test_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP))
set_regs_spsr_ss(task_pt_regs(task));
}
+NOKPROBE_SYMBOL(user_rewind_single_step);

void user_fastforward_single_step(struct task_struct *task)
{
@@ -413,6 +425,7 @@ void kernel_enable_single_step(struct pt_regs *regs)
mdscr_write(mdscr_read() | DBG_MDSCR_SS);
enable_debug_monitors(DBG_ACTIVE_EL1);
}
+NOKPROBE_SYMBOL(kernel_enable_single_step);

void kernel_disable_single_step(void)
{
@@ -420,12 +433,14 @@ void kernel_disable_single_step(void)
mdscr_write(mdscr_read() & ~DBG_MDSCR_SS);
disable_debug_monitors(DBG_ACTIVE_EL1);
}
+NOKPROBE_SYMBOL(kernel_disable_single_step);

int kernel_active_single_step(void)
{
WARN_ON(!irqs_disabled());
return mdscr_read() & DBG_MDSCR_SS;
}
+NOKPROBE_SYMBOL(kernel_active_single_step);

/* ptrace API */
void user_enable_single_step(struct task_struct *task)
@@ -433,8 +448,10 @@ void user_enable_single_step(struct task_struct *task)
set_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP);
set_regs_spsr_ss(task_pt_regs(task));
}
+NOKPROBE_SYMBOL(user_enable_single_step);

void user_disable_single_step(struct task_struct *task)
{
clear_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP);
}
+NOKPROBE_SYMBOL(user_disable_single_step);
diff --git a/arch/arm64/kernel/hw_breakpoint.c b/arch/arm64/kernel/hw_breakpoint.c
index ce21aa8..26a6bf7 100644
--- a/arch/arm64/kernel/hw_breakpoint.c
+++ b/arch/arm64/kernel/hw_breakpoint.c
@@ -24,6 +24,7 @@
#include <linux/cpu_pm.h>
#include <linux/errno.h>
#include <linux/hw_breakpoint.h>
+#include <linux/kprobes.h>
#include <linux/perf_event.h>
#include <linux/ptrace.h>
#include <linux/smp.h>
@@ -127,6 +128,7 @@ static u64 read_wb_reg(int reg, int n)

return val;
}
+NOKPROBE_SYMBOL(read_wb_reg);

static void write_wb_reg(int reg, int n, u64 val)
{
@@ -140,6 +142,7 @@ static void write_wb_reg(int reg, int n, u64 val)
}
isb();
}
+NOKPROBE_SYMBOL(write_wb_reg);

/*
* Convert a breakpoint privilege level to the corresponding exception
@@ -157,6 +160,7 @@ static enum dbg_active_el debug_exception_level(int privilege)
return -EINVAL;
}
}
+NOKPROBE_SYMBOL(debug_exception_level);

enum hw_breakpoint_ops {
HW_BREAKPOINT_INSTALL,
@@ -575,6 +579,7 @@ static void toggle_bp_registers(int reg, enum dbg_active_el el, int enable)
write_wb_reg(reg, i, ctrl);
}
}
+NOKPROBE_SYMBOL(toggle_bp_registers);

/*
* Debug exception handlers.
@@ -654,6 +659,7 @@ unlock:

return 0;
}
+NOKPROBE_SYMBOL(breakpoint_handler);

static int watchpoint_handler(unsigned long addr, unsigned int esr,
struct pt_regs *regs)
@@ -756,6 +762,7 @@ unlock:

return 0;
}
+NOKPROBE_SYMBOL(watchpoint_handler);

/*
* Handle single-step exception.
@@ -813,6 +820,7 @@ int reinstall_suspended_bps(struct pt_regs *regs)

return !handled_exception;
}
+NOKPROBE_SYMBOL(reinstall_suspended_bps);

/*
* Context-switcher for restoring suspended breakpoints.
diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c
index b5f063e..8c57f64 100644
--- a/arch/arm64/kernel/kgdb.c
+++ b/arch/arm64/kernel/kgdb.c
@@ -22,6 +22,7 @@
#include <linux/irq.h>
#include <linux/kdebug.h>
#include <linux/kgdb.h>
+#include <linux/kprobes.h>
#include <asm/traps.h>

struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = {
@@ -230,6 +231,7 @@ static int kgdb_brk_fn(struct pt_regs *regs, unsigned int esr)
kgdb_handle_exception(1, SIGTRAP, 0, regs);
return 0;
}
+NOKPROBE_SYMBOL(kgdb_brk_fn)

static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int esr)
{
@@ -238,12 +240,14 @@ static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int esr)

return 0;
}
+NOKPROBE_SYMBOL(kgdb_compiled_brk_fn);

static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr)
{
kgdb_handle_exception(1, SIGTRAP, 0, regs);
return 0;
}
+NOKPROBE_SYMBOL(kgdb_step_brk_fn);

static struct break_hook kgdb_brkpt_hook = {
.esr_mask = 0xffffffff,
--
2.5.0

Next message: David Long: "[PATCH v14 01/10] arm64: Add HAVE_REGS_AND_STACK_ACCESS_API feature"
Previous message: David Long: "[PATCH v14 06/10] arm64: Treat all entry code as non-kprobe-able"
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