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 <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Geert Uytterhoeven <[email protected]> Cc: Elvira Khabirova <[email protected]> Cc: Eugene Syromyatnikov <[email protected]> Cc: [email protected] Signed-off-by: Dmitry V. Levin <[email protected]> --- 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
