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authorPunit Agrawal <punit.agrawal@arm.com>2014-11-18 11:41:22 +0000
committerDavid Brown <david.brown@linaro.org>2015-12-03 16:53:44 -0800
commit520f902c78b66c9454ec2add6018cff96b7c60ad (patch)
tree2eb947bb560cee2762dce0fec70083e6d4666963
parente1cdd62cd18908c503eabf498b17996ed26e4e00 (diff)
downloadlinux-linaro-stable-520f902c78b66c9454ec2add6018cff96b7c60ad.tar.gz
arm64: Add support for hooks to handle undefined instructions
commit 9b79f52d1a702dd5b160f9d2ee0199c3122809bb upstream. Add support to register hooks for undefined instructions. The handlers will be called when the undefined instruction and the processor state (as contained in pstate) match criteria used at registration. Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: David Brown <david.brown@linaro.org>
-rw-r--r--arch/arm64/include/asm/insn.h2
-rw-r--r--arch/arm64/include/asm/traps.h16
-rw-r--r--arch/arm64/kernel/insn.c5
-rw-r--r--arch/arm64/kernel/traps.c66
4 files changed, 89 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h
index 56a9e63b6c33..1bb043018315 100644
--- a/arch/arm64/include/asm/insn.h
+++ b/arch/arm64/include/asm/insn.h
@@ -354,6 +354,8 @@ bool aarch64_insn_hotpatch_safe(u32 old_insn, u32 new_insn);
int aarch64_insn_patch_text_nosync(void *addr, u32 insn);
int aarch64_insn_patch_text_sync(void *addrs[], u32 insns[], int cnt);
int aarch64_insn_patch_text(void *addrs[], u32 insns[], int cnt);
+
+bool aarch32_insn_is_wide(u32 insn);
#endif /* __ASSEMBLY__ */
#endif /* __ASM_INSN_H */
diff --git a/arch/arm64/include/asm/traps.h b/arch/arm64/include/asm/traps.h
index 10ca8ff93cc2..232e4ba5d314 100644
--- a/arch/arm64/include/asm/traps.h
+++ b/arch/arm64/include/asm/traps.h
@@ -18,6 +18,22 @@
#ifndef __ASM_TRAP_H
#define __ASM_TRAP_H
+#include <linux/list.h>
+
+struct pt_regs;
+
+struct undef_hook {
+ struct list_head node;
+ u32 instr_mask;
+ u32 instr_val;
+ u64 pstate_mask;
+ u64 pstate_val;
+ int (*fn)(struct pt_regs *regs, u32 instr);
+};
+
+void register_undef_hook(struct undef_hook *hook);
+void unregister_undef_hook(struct undef_hook *hook);
+
static inline int in_exception_text(unsigned long ptr)
{
extern char __exception_text_start[];
diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c
index 8cd27fedc8b6..abb087060442 100644
--- a/arch/arm64/kernel/insn.c
+++ b/arch/arm64/kernel/insn.c
@@ -960,3 +960,8 @@ u32 aarch64_insn_gen_logical_shifted_reg(enum aarch64_insn_register dst,
return aarch64_insn_encode_immediate(AARCH64_INSN_IMM_6, insn, shift);
}
+
+bool aarch32_insn_is_wide(u32 insn)
+{
+ return insn >= 0xe800;
+}
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index de1b085e7963..0a801e3743d5 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -259,6 +259,69 @@ void arm64_notify_die(const char *str, struct pt_regs *regs,
}
}
+static LIST_HEAD(undef_hook);
+static DEFINE_RAW_SPINLOCK(undef_lock);
+
+void register_undef_hook(struct undef_hook *hook)
+{
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&undef_lock, flags);
+ list_add(&hook->node, &undef_hook);
+ raw_spin_unlock_irqrestore(&undef_lock, flags);
+}
+
+void unregister_undef_hook(struct undef_hook *hook)
+{
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&undef_lock, flags);
+ list_del(&hook->node);
+ raw_spin_unlock_irqrestore(&undef_lock, flags);
+}
+
+static int call_undef_hook(struct pt_regs *regs)
+{
+ struct undef_hook *hook;
+ unsigned long flags;
+ u32 instr;
+ int (*fn)(struct pt_regs *regs, u32 instr) = NULL;
+ void __user *pc = (void __user *)instruction_pointer(regs);
+
+ if (!user_mode(regs))
+ return 1;
+
+ if (compat_thumb_mode(regs)) {
+ /* 16-bit Thumb instruction */
+ if (get_user(instr, (u16 __user *)pc))
+ goto exit;
+ instr = le16_to_cpu(instr);
+ if (aarch32_insn_is_wide(instr)) {
+ u32 instr2;
+
+ if (get_user(instr2, (u16 __user *)(pc + 2)))
+ goto exit;
+ instr2 = le16_to_cpu(instr2);
+ instr = (instr << 16) | instr2;
+ }
+ } else {
+ /* 32-bit ARM instruction */
+ if (get_user(instr, (u32 __user *)pc))
+ goto exit;
+ instr = le32_to_cpu(instr);
+ }
+
+ raw_spin_lock_irqsave(&undef_lock, flags);
+ list_for_each_entry(hook, &undef_hook, node)
+ if ((instr & hook->instr_mask) == hook->instr_val &&
+ (regs->pstate & hook->pstate_mask) == hook->pstate_val)
+ fn = hook->fn;
+
+ raw_spin_unlock_irqrestore(&undef_lock, flags);
+exit:
+ return fn ? fn(regs, instr) : 1;
+}
+
asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
{
siginfo_t info;
@@ -268,6 +331,9 @@ asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
if (!aarch32_break_handler(regs))
return;
+ if (call_undef_hook(regs) == 0)
+ return;
+
if (show_unhandled_signals && unhandled_signal(current, SIGILL) &&
printk_ratelimit()) {
pr_info("%s[%d]: undefined instruction: pc=%p\n",