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authorMathieu Desnoyers <mathieu.desnoyers@efficios.com>2018-06-02 08:43:56 -0400
committerThomas Gleixner <tglx@linutronix.de>2018-06-06 11:58:31 +0200
commitb74406f37737c91c5ede7c625d9d31482a8a4290 (patch)
tree3954938fe9b662fd50ea4e847b4e6bf1d63528df /arch/arm
parent9800b9dc13cdffb7f627e4818ba7768ff62febac (diff)
arm: Add syscall detection for restartable sequences
Syscalls are not allowed inside restartable sequences, so add a call to rseq_syscall() at the very beginning of system call exiting path for CONFIG_DEBUG_RSEQ=y kernel. This could help us to detect whether there is a syscall issued inside restartable sequences. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Joel Fernandes <joelaf@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Watson <davejwatson@fb.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: Chris Lameter <cl@linux.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Andrew Hunter <ahh@google.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com> Cc: Paul Turner <pjt@google.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ben Maurer <bmaurer@fb.com> Cc: linux-api@vger.kernel.org Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lkml.kernel.org/r/20180602124408.8430-5-mathieu.desnoyers@efficios.com
Diffstat (limited to 'arch/arm')
-rw-r--r--arch/arm/kernel/entry-common.S25
-rw-r--r--arch/arm/kernel/signal.c7
2 files changed, 26 insertions, 6 deletions
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 3c4f88701f22..b427ef8ec8c6 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -39,12 +39,13 @@ saved_pc .req lr
.section .entry.text,"ax",%progbits
.align 5
-#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING))
+#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING) || \
+ IS_ENABLED(CONFIG_DEBUG_RSEQ))
/*
* This is the fast syscall return path. We do as little as possible here,
* such as avoiding writing r0 to the stack. We only use this path if we
- * have tracing and context tracking disabled - the overheads from those
- * features make this path too inefficient.
+ * have tracing, context tracking and rseq debug disabled - the overheads
+ * from those features make this path too inefficient.
*/
ret_fast_syscall:
UNWIND(.fnstart )
@@ -71,14 +72,20 @@ fast_work_pending:
/* fall through to work_pending */
#else
/*
- * The "replacement" ret_fast_syscall for when tracing or context tracking
- * is enabled. As we will need to call out to some C functions, we save
- * r0 first to avoid needing to save registers around each C function call.
+ * The "replacement" ret_fast_syscall for when tracing, context tracking,
+ * or rseq debug is enabled. As we will need to call out to some C functions,
+ * we save r0 first to avoid needing to save registers around each C function
+ * call.
*/
ret_fast_syscall:
UNWIND(.fnstart )
UNWIND(.cantunwind )
str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
+#if IS_ENABLED(CONFIG_DEBUG_RSEQ)
+ /* do_rseq_syscall needs interrupts enabled. */
+ mov r0, sp @ 'regs'
+ bl do_rseq_syscall
+#endif
disable_irq_notrace @ disable interrupts
ldr r2, [tsk, #TI_ADDR_LIMIT]
cmp r2, #TASK_SIZE
@@ -113,6 +120,12 @@ ENDPROC(ret_fast_syscall)
*/
ENTRY(ret_to_user)
ret_slow_syscall:
+#if IS_ENABLED(CONFIG_DEBUG_RSEQ)
+ /* do_rseq_syscall needs interrupts enabled. */
+ enable_irq_notrace @ enable interrupts
+ mov r0, sp @ 'regs'
+ bl do_rseq_syscall
+#endif
disable_irq_notrace @ disable interrupts
ENTRY(ret_to_user_from_irq)
ldr r2, [tsk, #TI_ADDR_LIMIT]
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 5879ab3f53c1..f09e9d66d605 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -710,3 +710,10 @@ asmlinkage void addr_limit_check_failed(void)
{
addr_limit_user_check();
}
+
+#ifdef CONFIG_DEBUG_RSEQ
+asmlinkage void do_rseq_syscall(struct pt_regs *regs)
+{
+ rseq_syscall(regs);
+}
+#endif