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Message-Id: <20190506143054.480275434@linuxfoundation.org>
Date: Mon, 6 May 2019 16:32:22 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Catalin Marinas <catalin.marinas@....com>,
Mark Rutland <mark.rutland@....com>,
Julien Thierry <julien.thierry@....com>,
Alex Bennée <alex.bennee@...aro.org>,
Will Deacon <will.deacon@....com>,
Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH 4.14 14/75] arm64: Fix single stepping in kernel traps
From: Julien Thierry <julien.thierry@....com>
commit 6436beeee5721a8e906e9eabf866f12d04470437 upstream.
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@....com>
Cc: Mark Rutland <mark.rutland@....com>
Signed-off-by: Julien Thierry <julien.thierry@....com>
Reviewed-by: Alex Bennée <alex.bennee@...aro.org>
[will: replaced AARCH32_INSN_SIZE with 4]
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
arch/arm64/include/asm/traps.h | 6 ++++++
arch/arm64/kernel/armv8_deprecated.c | 8 ++++----
arch/arm64/kernel/cpufeature.c | 2 +-
arch/arm64/kernel/traps.c | 21 ++++++++++++++++-----
4 files changed, 27 insertions(+), 10 deletions(-)
--- a/arch/arm64/include/asm/traps.h
+++ b/arch/arm64/include/asm/traps.h
@@ -37,6 +37,12 @@ void unregister_undef_hook(struct undef_
void arm64_notify_segfault(struct pt_regs *regs, unsigned long addr);
+/*
+ * Move regs->pc to next instruction and do necessary setup before it
+ * is executed.
+ */
+void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size);
+
static inline int __in_irqentry_text(unsigned long ptr)
{
return ptr >= (unsigned long)&__irqentry_text_start &&
--- a/arch/arm64/kernel/armv8_deprecated.c
+++ b/arch/arm64/kernel/armv8_deprecated.c
@@ -431,7 +431,7 @@ ret:
pr_warn_ratelimited("\"%s\" (%ld) uses obsolete SWP{B} instruction at 0x%llx\n",
current->comm, (unsigned long)current->pid, regs->pc);
- regs->pc += 4;
+ arm64_skip_faulting_instruction(regs, 4);
return 0;
fault:
@@ -512,7 +512,7 @@ ret:
pr_warn_ratelimited("\"%s\" (%ld) uses deprecated CP15 Barrier instruction at 0x%llx\n",
current->comm, (unsigned long)current->pid, regs->pc);
- regs->pc += 4;
+ arm64_skip_faulting_instruction(regs, 4);
return 0;
}
@@ -586,14 +586,14 @@ static int compat_setend_handler(struct
static int a32_setend_handler(struct pt_regs *regs, u32 instr)
{
int rc = compat_setend_handler(regs, (instr >> 9) & 1);
- regs->pc += 4;
+ arm64_skip_faulting_instruction(regs, 4);
return rc;
}
static int t16_setend_handler(struct pt_regs *regs, u32 instr)
{
int rc = compat_setend_handler(regs, (instr >> 3) & 1);
- regs->pc += 2;
+ arm64_skip_faulting_instruction(regs, 2);
return rc;
}
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1398,7 +1398,7 @@ static int emulate_mrs(struct pt_regs *r
if (!rc) {
dst = aarch64_insn_decode_register(AARCH64_INSN_REGTYPE_RT, insn);
pt_regs_write_reg(regs, dst, val);
- regs->pc += 4;
+ arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
}
return rc;
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -296,6 +296,17 @@ void arm64_notify_die(const char *str, s
}
}
+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);
@@ -483,7 +494,7 @@ static void user_cache_maint_handler(uns
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)
@@ -493,7 +504,7 @@ static void ctr_read_handler(unsigned in
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)
@@ -501,7 +512,7 @@ static void cntvct_read_handler(unsigned
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)
@@ -509,7 +520,7 @@ static void cntfrq_read_handler(unsigned
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 {
@@ -756,7 +767,7 @@ static int bug_handler(struct pt_regs *r
}
/* 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;
}
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