[PATCH 1/3] arm64: rseq: Implement backend rseq calls and select HAVE_RSEQ

Will Deacon
2018-06-25T17:54:24Z

Implement calls to rseq_signal_deliver, rseq_handle_notify_resume
and rseq_syscall so that we can select HAVE_RSEQ on arm64.

Signed-off-by: Will Deacon <will.deacon@arm.com>
---
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/unistd.h | 2 +-
arch/arm64/include/asm/unistd32.h | 2 ++
arch/arm64/kernel/entry.S | 2 ++
arch/arm64/kernel/ptrace.c | 2 ++
arch/arm64/kernel/signal.c | 3 +++
6 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 42c090cf0292..26cb550673b2 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -127,6 +127,7 @@ config ARM64
select HAVE_PERF_USER_STACK_DUMP
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_RCU_TABLE_FREE
+ select HAVE_RSEQ
select HAVE_STACKPROTECTOR
select HAVE_SYSCALL_TRACEPOINTS
select HAVE_KPROBES
diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h
index a0baa9af5487..e0d0f5b856e7 100644
--- a/arch/arm64/include/asm/unistd.h
+++ b/arch/arm64/include/asm/unistd.h
@@ -43,7 +43,7 @@
#define __ARM_NR_compat_cacheflush (__ARM_NR_COMPAT_BASE+2)
#define __ARM_NR_compat_set_tls (__ARM_NR_COMPAT_BASE+5)

-#define __NR_compat_syscalls 398
+#define __NR_compat_syscalls 399
#endif

#define __ARCH_WANT_SYS_CLONE
diff --git a/arch/arm64/include/asm/unistd32.h b/arch/arm64/include/asm/unistd32.h
index ef292160748c..0fdc7ef8a776 100644
--- a/arch/arm64/include/asm/unistd32.h
+++ b/arch/arm64/include/asm/unistd32.h
@@ -817,6 +817,8 @@ __SYSCALL(__NR_pkey_alloc, sys_pkey_alloc)
__SYSCALL(__NR_pkey_free, sys_pkey_free)
#define __NR_statx 397
__SYSCALL(__NR_statx, sys_statx)
+#define __NR_rseq 398
+__SYSCALL(__NR_rseq, sys_rseq)

/*
* Please add new compat syscalls above this comment and update
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 28ad8799406f..1eda9e1a1f4a 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -904,6 +904,7 @@ ENDPROC(el0_error)
ret_fast_syscall:
disable_daif
str x0, [sp, #S_X0] // returned x0
+#ifndef CONFIG_DEBUG_RSEQ
ldr x1, [tsk, #TSK_TI_FLAGS] // re-check for syscall tracing
and x2, x1, #_TIF_SYSCALL_WORK
cbnz x2, ret_fast_syscall_trace
@@ -911,6 +912,7 @@ ret_fast_syscall:
cbnz x2, work_pending
enable_step_tsk x1, x2
kernel_exit 0
+#endif
ret_fast_syscall_trace:
enable_daif
b __sys_trace_return_skipped // we already saved x0
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 5c338ce5a7fa..9f479c111675 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -1656,6 +1656,8 @@ asmlinkage void syscall_trace_exit(struct pt_regs *regs)

if (test_thread_flag(TIF_SYSCALL_TRACE))
tracehook_report_syscall(regs, PTRACE_SYSCALL_EXIT);
+
+ rseq_syscall(regs);
}

/*
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 511af13e8d8f..e3b1d1b0aee8 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -802,6 +802,8 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
int usig = ksig->sig;
int ret;

+ rseq_signal_deliver(ksig, regs);
+
/*
* Set up the stack frame
*/
@@ -940,6 +942,7 @@ asmlinkage void do_notify_resume(struct pt_regs *regs,
if (thread_flags & _TIF_NOTIFY_RESUME) {
clear_thread_flag(TIF_NOTIFY_RESUME);
tracehook_notify_resume(regs);
+ rseq_handle_notify_resume(NULL, regs);
}

if (thread_flags & _TIF_FOREIGN_FPSTATE)
--
2.1.4