The patch titled Subject: ia64: fix user_stack_pointer() for ptrace() has been added to the -mm tree. Its filename is ia64-fix-user_stack_pointer-for-ptrace.patch

This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/ia64-fix-user_stack_pointer-for-pt... and later at https://ozlabs.org/~akpm/mmotm/broken-out/ia64-fix-user_stack_pointer-for-pt...

Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next and is updated there every 3-4 working days

------------------------------------------------------ From: Sergei Trofimovich slyfox@gentoo.org Subject: ia64: fix user_stack_pointer() for ptrace()

ia64 has two stacks: - memory stack (or stack), pointed at by by r12 - register backing store (register stack), pointed at ar.bsp/ar.bspstore with complications around dirty register frame on CPU.

In https://bugs.gentoo.org/769614 Dmitry noticed that PTRACE_GET_SYSCALL_INFO returns register stack instead memory stack.

The bug comes from the fact that user_stack_pointer() and current_user_stack_pointer() don't return the same register:

ulong user_stack_pointer(struct pt_regs *regs) { return regs->ar_bspstore; } #define current_user_stack_pointer() (current_pt_regs()->r12)

The change gets both back in sync.

I think ptrace(PTRACE_GET_SYSCALL_INFO) is the only affected user by this bug on ia64.

The change fixes 'rt_sigreturn.gen.test' strace test where it was observed initially.

Link: https://lkml.kernel.org/r/20210331084447.2561532-1-slyfox@gentoo.org Link: https://bugs.gentoo.org/769614 Signed-off-by: Sergei Trofimovich slyfox@gentoo.org Reported-by: Dmitry V. Levin ldv@altlinux.org Cc: Oleg Nesterov oleg@redhat.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

arch/ia64/include/asm/ptrace.h | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-)

--- a/arch/ia64/include/asm/ptrace.h~ia64-fix-user_stack_pointer-for-ptrace +++ a/arch/ia64/include/asm/ptrace.h @@ -54,8 +54,7 @@

static inline unsigned long user_stack_pointer(struct pt_regs *regs) { - /* FIXME: should this be bspstore + nr_dirty regs? */ - return regs->ar_bspstore; + return regs->r12; }

static inline int is_syscall_success(struct pt_regs *regs) @@ -79,11 +78,6 @@ static inline long regs_return_value(str unsigned long __ip = instruction_pointer(regs); \ (__ip & ~3UL) + ((__ip & 3UL) << 2); \ }) -/* - * Why not default? Because user_stack_pointer() on ia64 gives register - * stack backing store instead... - */ -#define current_user_stack_pointer() (current_pt_regs()->r12)

/* given a pointer to a task_struct, return the user's pt_regs */ # define task_pt_regs(t) (((struct pt_regs *) ((char *) (t) + IA64_STK_OFFSET)) - 1) _

Patches currently in -mm which might be from slyfox@gentoo.org are

ia64-fix-user_stack_pointer-for-ptrace.patch ia64-drop-unused-ia64_fw_emu-ifdef.patch ia64-simplify-code-flow-around-swiotlb-init.patch ia64-fix-efi_debug-build.patch ia64-mca-always-make-ia64_mca_debug-an-expression.patch mm-page_alloc-ignore-init_on_free=1-for-debug_pagealloc=1.patch