On Thu, Jan 03, 2019 at 06:13:59PM +0000, Will Deacon wrote:
The syscall number may have been changed by a tracer, so we should pass the actual number in from the caller instead of pulling it from the saved r7 value directly.
Reviewed-by: Dave Martin Dave.Martin@arm.com
I was confused by the history here: commit 4141c857fd09 ("arm64: convert raw syscall invocation to C") breaks syscall changing via discarding the return from syscall_trace_enter() (which would also break this case for compat), but the subsequent patch that migrates the syscall code to C appears to fix it again.
Cc: stable@vger.kernel.org Cc: Dave Martin Dave.Martin@arm.com Cc: Pi-Hsun Shih pihsun@chromium.org Signed-off-by: Will Deacon will.deacon@arm.com
arch/arm64/kernel/sys_compat.c | 9 ++++----- arch/arm64/kernel/syscall.c | 9 ++++----- 2 files changed, 8 insertions(+), 10 deletions(-)
diff --git a/arch/arm64/kernel/sys_compat.c b/arch/arm64/kernel/sys_compat.c index 5972b7533fa0..54c29cd38ff9 100644 --- a/arch/arm64/kernel/sys_compat.c +++ b/arch/arm64/kernel/sys_compat.c @@ -66,12 +66,11 @@ do_compat_cache_op(unsigned long start, unsigned long end, int flags) /*
- Handle all unrecognised system calls.
*/ -long compat_arm_syscall(struct pt_regs *regs) +long compat_arm_syscall(struct pt_regs *regs, int scno) {
- unsigned int no = regs->regs[7]; void __user *addr;
- switch (no) {
- switch (scno) { /*
- Flush a region from virtual address 'r0' to virtual address 'r1'
- _exclusive_. There is no alignment requirement on either address;
@@ -107,7 +106,7 @@ long compat_arm_syscall(struct pt_regs *regs) * way the calling program can gracefully determine whether * a feature is supported. */
if (no < __ARM_NR_compat_syscall_end)
if (scno < __ARM_NR_compat_syscall_end) return -ENOSYS;@@ -116,6 +115,6 @@ long compat_arm_syscall(struct pt_regs *regs) (compat_thumb_mode(regs) ? 2 : 4); arm64_notify_die("Oops - bad compat syscall(2)", regs,
SIGILL, ILL_ILLTRP, addr, no);
SIGILL, ILL_ILLTRP, addr, scno);} diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c index 032d22312881..5610ac01c1ec 100644 --- a/arch/arm64/kernel/syscall.c +++ b/arch/arm64/kernel/syscall.c @@ -13,16 +13,15 @@ #include <asm/thread_info.h> #include <asm/unistd.h> -long compat_arm_syscall(struct pt_regs *regs);
+long compat_arm_syscall(struct pt_regs *regs, int scno); long sys_ni_syscall(void); -asmlinkage long do_ni_syscall(struct pt_regs *regs) +static long do_ni_syscall(struct pt_regs *regs, int scno) { #ifdef CONFIG_COMPAT long ret; if (is_compat_task()) {
ret = compat_arm_syscall(regs);
ret = compat_arm_syscall(regs, scno);@@ -47,7 +46,7 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno, syscall_fn = syscall_table[array_index_nospec(scno, sc_nr)]; ret = __invoke_syscall(regs, syscall_fn); } else {
ret = do_ni_syscall(regs);
ret = do_ni_syscall(regs, scno);regs->regs[0] = ret; -- 2.1.4
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