arm64: debug: consolidate software breakpoint handlers

The software breakpoint handlers are hooked in directly from ptrace,
which makes it difficult to add additional handlers for things like
kprobes and kgdb.

This patch moves the handling code into debug-monitors.c, where we can
dispatch to different debug subsystems more easily.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/include/asm/debug-monitors.h b/arch/arm64/include/asm/debug-monitors.h
index 7eaa0b302493491b781b0a8c432b66bdac57fd43..ef8235c68c092674ed0c628733bbc7a6b02404b5 100644 (file)
--- a/arch/arm64/include/asm/debug-monitors.h
+++ b/arch/arm64/include/asm/debug-monitors.h
@@ -83,6 +83,15 @@ static inline int reinstall_suspended_bps(struct pt_regs *regs)
 }
 #endif
 
+#ifdef CONFIG_COMPAT
+int aarch32_break_handler(struct pt_regs *regs);
+#else
+static int aarch32_break_handler(struct pt_regs *regs)
+{
+       return -EFAULT;
+}
+#endif
+
 #endif /* __ASSEMBLY */
 #endif /* __KERNEL__ */
 #endif /* __ASM_DEBUG_MONITORS_H */

diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
index 7304fa2fd9fafe0fceeeb7c36fec196cea3651dd..41e59e2459ffcb7109339f56f60ed9b69387133b 100644 (file)
--- a/arch/arm64/include/asm/ptrace.h
+++ b/arch/arm64/include/asm/ptrace.h
@@ -171,7 +171,5 @@ extern unsigned long profile_pc(struct pt_regs *regs);
 #define profile_pc(regs) instruction_pointer(regs)
 #endif
 
-extern int aarch32_break_trap(struct pt_regs *regs);
-
 #endif /* __ASSEMBLY__ */
 #endif

diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
index f4726dc054b3bbcdd7c7a5d98d3733b6a893ea3e..08018e3df580c65d259470175fc95319d0589322 100644 (file)
--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -24,6 +24,7 @@
 #include <linux/init.h>
 #include <linux/ptrace.h>
 #include <linux/stat.h>
+#include <linux/uaccess.h>
 
 #include <asm/debug-monitors.h>
 #include <asm/local.h>
@@ -226,13 +227,74 @@ static int single_step_handler(unsigned long addr, unsigned int esr,
        return 0;
 }
 
-static int __init single_step_init(void)
+static int brk_handler(unsigned long addr, unsigned int esr,
+                      struct pt_regs *regs)
+{
+       siginfo_t info;
+
+       if (!user_mode(regs))
+               return -EFAULT;
+
+       info = (siginfo_t) {
+               .si_signo = SIGTRAP,
+               .si_errno = 0,
+               .si_code  = TRAP_BRKPT,
+               .si_addr  = (void __user *)instruction_pointer(regs),
+       };
+
+       force_sig_info(SIGTRAP, &info, current);
+       return 0;
+}
+
+int aarch32_break_handler(struct pt_regs *regs)
+{
+       siginfo_t info;
+       unsigned int instr;
+       bool bp = false;
+       void __user *pc = (void __user *)instruction_pointer(regs);
+
+       if (!compat_user_mode(regs))
+               return -EFAULT;
+
+       if (compat_thumb_mode(regs)) {
+               /* get 16-bit Thumb instruction */
+               get_user(instr, (u16 __user *)pc);
+               if (instr == AARCH32_BREAK_THUMB2_LO) {
+                       /* get second half of 32-bit Thumb-2 instruction */
+                       get_user(instr, (u16 __user *)(pc + 2));
+                       bp = instr == AARCH32_BREAK_THUMB2_HI;
+               } else {
+                       bp = instr == AARCH32_BREAK_THUMB;
+               }
+       } else {
+               /* 32-bit ARM instruction */
+               get_user(instr, (u32 __user *)pc);
+               bp = (instr & ~0xf0000000) == AARCH32_BREAK_ARM;
+       }
+
+       if (!bp)
+               return -EFAULT;
+
+       info = (siginfo_t) {
+               .si_signo = SIGTRAP,
+               .si_errno = 0,
+               .si_code  = TRAP_BRKPT,
+               .si_addr  = pc,
+       };
+
+       force_sig_info(SIGTRAP, &info, current);
+       return 0;
+}
+
+static int __init debug_traps_init(void)
 {
        hook_debug_fault_code(DBG_ESR_EVT_HWSS, single_step_handler, SIGTRAP,
                              TRAP_HWBKPT, "single-step handler");
+       hook_debug_fault_code(DBG_ESR_EVT_BRK, brk_handler, SIGTRAP,
+                             TRAP_BRKPT, "ptrace BRK handler");
        return 0;
 }
-arch_initcall(single_step_init);
+arch_initcall(debug_traps_init);
 
 /* Re-enable single step for syscall restarting. */
 void user_rewind_single_step(struct task_struct *task)

diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index aebfc1519e8ed2ade8e899e87b00c6163aa71d12..7190a6544caba71f70de13bee51c278d2b3e0b96 100644 (file)
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -53,28 +53,6 @@ void ptrace_disable(struct task_struct *child)
 {
 }
 
-/*
- * Handle hitting a breakpoint.
- */
-static int ptrace_break(struct pt_regs *regs)
-{
-       siginfo_t info = {
-               .si_signo = SIGTRAP,
-               .si_errno = 0,
-               .si_code  = TRAP_BRKPT,
-               .si_addr  = (void __user *)instruction_pointer(regs),
-       };
-
-       force_sig_info(SIGTRAP, &info, current);
-       return 0;
-}
-
-static int arm64_break_trap(unsigned long addr, unsigned int esr,
-                           struct pt_regs *regs)
-{
-       return ptrace_break(regs);
-}
-
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 /*
  * Handle hitting a HW-breakpoint.
@@ -819,33 +797,6 @@ static const struct user_regset_view user_aarch32_view = {
        .regsets = aarch32_regsets, .n = ARRAY_SIZE(aarch32_regsets)
 };
 
-int aarch32_break_trap(struct pt_regs *regs)
-{
-       unsigned int instr;
-       bool bp = false;
-       void __user *pc = (void __user *)instruction_pointer(regs);
-
-       if (compat_thumb_mode(regs)) {
-               /* get 16-bit Thumb instruction */
-               get_user(instr, (u16 __user *)pc);
-               if (instr == AARCH32_BREAK_THUMB2_LO) {
-                       /* get second half of 32-bit Thumb-2 instruction */
-                       get_user(instr, (u16 __user *)(pc + 2));
-                       bp = instr == AARCH32_BREAK_THUMB2_HI;
-               } else {
-                       bp = instr == AARCH32_BREAK_THUMB;
-               }
-       } else {
-               /* 32-bit ARM instruction */
-               get_user(instr, (u32 __user *)pc);
-               bp = (instr & ~0xf0000000) == AARCH32_BREAK_ARM;
-       }
-
-       if (bp)
-               return ptrace_break(regs);
-       return 1;
-}
-
 static int compat_ptrace_read_user(struct task_struct *tsk, compat_ulong_t off,
                                   compat_ulong_t __user *ret)
 {
@@ -1113,16 +1064,6 @@ long arch_ptrace(struct task_struct *child, long request,
        return ptrace_request(child, request, addr, data);
 }
 
-
-static int __init ptrace_break_init(void)
-{
-       hook_debug_fault_code(DBG_ESR_EVT_BRK, arm64_break_trap, SIGTRAP,
-                             TRAP_BRKPT, "ptrace BRK handler");
-       return 0;
-}
-core_initcall(ptrace_break_init);
-
-
 asmlinkage int syscall_trace(int dir, struct pt_regs *regs)
 {
        unsigned long saved_reg;

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index f30852d28590358c6780a22c14049f92a124bdb8..7ffadddb645d32cda5fd54a0c2a5a0c5456b4018 100644 (file)
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -32,6 +32,7 @@
 #include <linux/syscalls.h>
 
 #include <asm/atomic.h>
+#include <asm/debug-monitors.h>
 #include <asm/traps.h>
 #include <asm/stacktrace.h>
 #include <asm/exception.h>
@@ -261,11 +262,9 @@ asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
        siginfo_t info;
        void __user *pc = (void __user *)instruction_pointer(regs);
 
-#ifdef CONFIG_COMPAT
        /* check for AArch32 breakpoint instructions */
-       if (compat_user_mode(regs) && aarch32_break_trap(regs) == 0)
+       if (!aarch32_break_handler(regs))
                return;
-#endif
 
        if (show_unhandled_signals && unhandled_signal(current, SIGILL) &&
            printk_ratelimit()) {