arm64: Fix single stepping in kernel traps
Software Step exception is missing after stepping a trapped instruction.
Ensure SPSR.SS gets set to 0 after emulating/skipping a trapped instruction
before doing ERET.
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
[will: replaced AARCH32_INSN_SIZE with 4]
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 5ea4b85..a1b7d64 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -293,6 +293,17 @@ void arm64_notify_die(const char *str, struct pt_regs *regs,
}
}
+void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
+{
+ regs->pc += size;
+
+ /*
+ * If we were single stepping, we want to get the step exception after
+ * we return from the trap.
+ */
+ user_fastforward_single_step(current);
+}
+
static LIST_HEAD(undef_hook);
static DEFINE_RAW_SPINLOCK(undef_lock);
@@ -480,7 +491,7 @@ static void user_cache_maint_handler(unsigned int esr, struct pt_regs *regs)
if (ret)
arm64_notify_segfault(regs, address);
else
- regs->pc += 4;
+ arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
}
static void ctr_read_handler(unsigned int esr, struct pt_regs *regs)
@@ -490,7 +501,7 @@ static void ctr_read_handler(unsigned int esr, struct pt_regs *regs)
pt_regs_write_reg(regs, rt, val);
- regs->pc += 4;
+ arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
}
static void cntvct_read_handler(unsigned int esr, struct pt_regs *regs)
@@ -498,7 +509,7 @@ static void cntvct_read_handler(unsigned int esr, struct pt_regs *regs)
int rt = (esr & ESR_ELx_SYS64_ISS_RT_MASK) >> ESR_ELx_SYS64_ISS_RT_SHIFT;
pt_regs_write_reg(regs, rt, arch_counter_get_cntvct());
- regs->pc += 4;
+ arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
}
static void cntfrq_read_handler(unsigned int esr, struct pt_regs *regs)
@@ -506,7 +517,7 @@ static void cntfrq_read_handler(unsigned int esr, struct pt_regs *regs)
int rt = (esr & ESR_ELx_SYS64_ISS_RT_MASK) >> ESR_ELx_SYS64_ISS_RT_SHIFT;
pt_regs_write_reg(regs, rt, arch_timer_get_rate());
- regs->pc += 4;
+ arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
}
struct sys64_hook {
@@ -761,7 +772,7 @@ static int bug_handler(struct pt_regs *regs, unsigned int esr)
}
/* If thread survives, skip over the BUG instruction and continue: */
- regs->pc += AARCH64_INSN_SIZE; /* skip BRK and resume */
+ arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
return DBG_HOOK_HANDLED;
}