Add a generic wrapper syscall_get_arguments() that checks
its arguments and calls arch-specific __syscall_get_arguments().
Likewise, add a generic wrapper syscall_set_arguments() that checks
its arguments and calls arch-specific __syscall_set_arguments().
This is the first step on the way of getting rid of BUGs, BUG_ONs,
and replicated error checks in arch-specific asm/syscall.h files.
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: Elvira Khabirova <lineprinter@xxxxxxxxxxxx>
Cc: Eugene Syromyatnikov <esyr@xxxxxxxxxx>
Cc: linux-arch@xxxxxxxxxxxxxxx
Signed-off-by: Dmitry V. Levin <ldv@xxxxxxxxxxxx>
---
Notes:
v7: unchanged
v6: initial revision
include/asm-generic/syscall.h | 47 +++++++++++++++++++++++++++++++++--
1 file changed, 45 insertions(+), 2 deletions(-)
diff --git a/include/asm-generic/syscall.h b/include/asm-generic/syscall.h
index 9863a5f8fbe8..fdefe27fa63f 100644
--- a/include/asm-generic/syscall.h
+++ b/include/asm-generic/syscall.h
@@ -122,10 +122,34 @@ syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
* entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
* It's invalid to call this with @i + @n > 6; we only support system calls
* taking up to 6 arguments.
+ *
+ * This function is a wrapper around arch-specific __syscall_get_arguments.
*/
static void
+__syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
+ unsigned int i, unsigned int n, unsigned long *args);
+
+static inline void
syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
- unsigned int i, unsigned int n, unsigned long *args);
+ unsigned int i, unsigned int n, unsigned long *args)
+{
+ /*
+ * Ideally there should have been a BUILD_BUG_ON(i + n > 6)
+ * instead of these checks because it is a "cannot happen"
+ * kind of assertion.
+ */
+ if (WARN_ON_ONCE(i > 6)) {
+ memset(args, 0, n * sizeof(args[0]));
+ return;
+ }
+ if (WARN_ON_ONCE(n > 6 - i)) {
+ unsigned int extra = n - (6 - i);
+
+ n = 6 - i;
+ memset(&args[n], 0, extra * sizeof(args[0]));
+ }
+ __syscall_get_arguments(task, regs, i, n, args);
+}
/**
* syscall_set_arguments - change system call parameter value
@@ -143,11 +167,30 @@ syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
* entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
* It's invalid to call this with @i + @n > 6; we only support system calls
* taking up to 6 arguments.
+ *
+ * This function is a wrapper around arch-specific __syscall_set_arguments.
*/
static void
+__syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
+ unsigned int i, unsigned int n,
+ const unsigned long *args);
+
+static inline void
syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
unsigned int i, unsigned int n,
- const unsigned long *args);
+ const unsigned long *args)
+{
+ /*
+ * Ideally there should have been a BUILD_BUG_ON(i + n > 6)
+ * instead of these checks because it is a "cannot happen"
+ * kind of assertion.
+ */
+ if (WARN_ON_ONCE(i > 6))
+ return;
+ if (WARN_ON_ONCE(n > 6 - i))
+ n = 6 - i;
+ __syscall_set_arguments(task, regs, i, n, args);
+}
/**
* syscall_get_arch - return the AUDIT_ARCH for the current system call
--
ldv
