[PATCH v4 5/7] arm64: add support for uaccess logging

[Peter Collingbourne]

arm64 does not use CONFIG_GENERIC_ENTRY, so add the support for
uaccess logging directly to the architecture.

Link: https://linux-review.googlesource.com/id/I88de539fb9c4a9d27fa8cccbe201a6e4382faf89
Signed-off-by: Peter Collingbourne <pcc at google.com>
---
v4:
- remove unnecessary hunk

 arch/arm64/Kconfig                   | 1 +
 arch/arm64/include/asm/thread_info.h | 7 ++++++-
 arch/arm64/kernel/ptrace.c           | 7 +++++++
 arch/arm64/kernel/signal.c           | 5 +++++
 4 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index c4207cf9bb17..6023946abe4a 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -161,6 +161,7 @@ config ARM64
 	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
+	select HAVE_ARCH_UACCESS_BUFFER
 	select HAVE_ARCH_VMAP_STACK
 	select HAVE_ARM_SMCCC
 	select HAVE_ASM_MODVERSIONS
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index e1317b7c4525..0461b36251ea 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -82,6 +82,8 @@ int arch_dup_task_struct(struct task_struct *dst,
 #define TIF_SVE_VL_INHERIT	24	/* Inherit SVE vl_onexec across exec */
 #define TIF_SSBD		25	/* Wants SSB mitigation */
 #define TIF_TAGGED_ADDR		26	/* Allow tagged user addresses */
+#define TIF_UACCESS_BUFFER_ENTRY 27     /* thread has non-zero uaccess_desc_addr_addr */
+#define TIF_UACCESS_BUFFER_EXIT  28     /* thread has non-zero kcur */
 
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
@@ -98,6 +100,8 @@ int arch_dup_task_struct(struct task_struct *dst,
 #define _TIF_SVE		(1 << TIF_SVE)
 #define _TIF_MTE_ASYNC_FAULT	(1 << TIF_MTE_ASYNC_FAULT)
 #define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
+#define _TIF_UACCESS_BUFFER_ENTRY	(1 << TIF_UACCESS_BUFFER_ENTRY)
+#define _TIF_UACCESS_BUFFER_EXIT	(1 << TIF_UACCESS_BUFFER_EXIT)
 
 #define _TIF_WORK_MASK		(_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
 				 _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \
@@ -106,7 +110,8 @@ int arch_dup_task_struct(struct task_struct *dst,
 
 #define _TIF_SYSCALL_WORK	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
 				 _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \
-				 _TIF_SYSCALL_EMU)
+				 _TIF_SYSCALL_EMU | _TIF_UACCESS_BUFFER_ENTRY | \
+				 _TIF_UACCESS_BUFFER_EXIT)
 
 #ifdef CONFIG_SHADOW_CALL_STACK
 #define INIT_SCS							\
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 88a9034fb9b5..283372eccaeb 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -29,6 +29,7 @@
 #include <linux/regset.h>
 #include <linux/tracehook.h>
 #include <linux/elf.h>
+#include <linux/uaccess-buffer.h>
 
 #include <asm/compat.h>
 #include <asm/cpufeature.h>
@@ -1854,6 +1855,9 @@ int syscall_trace_enter(struct pt_regs *regs)
 	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
 		trace_sys_enter(regs, regs->syscallno);
 
+	if (flags & _TIF_UACCESS_BUFFER_ENTRY)
+		uaccess_buffer_syscall_entry();
+
 	audit_syscall_entry(regs->syscallno, regs->orig_x0, regs->regs[1],
 			    regs->regs[2], regs->regs[3]);
 
@@ -1866,6 +1870,9 @@ void syscall_trace_exit(struct pt_regs *regs)
 
 	audit_syscall_exit(regs);
 
+	if (flags & _TIF_UACCESS_BUFFER_EXIT)
+		uaccess_buffer_syscall_exit();
+
 	if (flags & _TIF_SYSCALL_TRACEPOINT)
 		trace_sys_exit(regs, syscall_get_return_value(current, regs));
 
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 8f6372b44b65..5bbd98e5c257 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -20,6 +20,7 @@
 #include <linux/tracehook.h>
 #include <linux/ratelimit.h>
 #include <linux/syscalls.h>
+#include <linux/uaccess-buffer.h>
 
 #include <asm/daifflags.h>
 #include <asm/debug-monitors.h>
@@ -919,6 +920,8 @@ static void do_signal(struct pt_regs *regs)
 
 void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags)
 {
+	bool uaccess_buffer_pending = uaccess_buffer_pre_exit_loop();
+
 	do {
 		if (thread_flags & _TIF_NEED_RESCHED) {
 			/* Unmask Debug and SError for the next task */
@@ -950,6 +953,8 @@ void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags)
 		local_daif_mask();
 		thread_flags = READ_ONCE(current_thread_info()->flags);
 	} while (thread_flags & _TIF_WORK_MASK);
+
+	uaccess_buffer_post_exit_loop(uaccess_buffer_pending);
 }
 
 unsigned long __ro_after_init signal_minsigstksz;
-- 
2.34.1.173.g76aa8bc2d0-goog