linux.git/arch/arm/kernel/ptrace.c, branch for-next

Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm

2023-08-31T19:49:10+00:00

Pull ARM updates from Russell King:

 - Refactor VFP code and convert to C code (Ard Biesheuvel)

 - Fix hardware breakpoint single-stepping using bpf_overflow_handler

 - Make SMP stop calls asynchronous allowing panic from irq context to
   work

 - Fix for kernel-doc warnings for locomo

* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
  Revert part of ae1f8d793a19 ("ARM: 9304/1: add prototype for function called only from asm")
  ARM: 9318/1: locomo: move kernel-doc to prevent warnings
  ARM: 9317/1: kexec: Make smp stop calls asynchronous
  ARM: 9316/1: hw_breakpoint: fix single-stepping when using bpf_overflow_handler
  ARM: entry: Make asm coproc dispatch code NWFPE only
  ARM: iwmmxt: Use undef hook to enable coprocessor for task
  ARM: entry: Disregard Thumb undef exception in coproc dispatch
  ARM: vfp: Use undef hook for handling VFP exceptions
  ARM: kernel: Get rid of thread_info::used_cp[] array
  ARM: vfp: Reimplement VFP exception entry in C code
  ARM: vfp: Remove workaround for Feroceon CPUs
  ARM: vfp: Record VFP bounces as perf emulation faults

ARM: ptrace: Restore syscall skipping for tracers

2023-08-16T20:58:49+00:00

Since commit 4e57a4ddf6b0 ("ARM: 9107/1: syscall: always store
thread_info->abi_syscall"), the seccomp selftests "syscall_errno"
and "syscall_faked" have been broken. Both seccomp and PTRACE depend
on using the special value of "-1" for skipping syscalls. This value
wasn't working because it was getting masked by __NR_SYSCALL_MASK in
both PTRACE_SET_SYSCALL and get_syscall_nr().

Explicitly test for -1 in PTRACE_SET_SYSCALL and get_syscall_nr(),
leaving it exposed when present, allowing tracers to skip syscalls
again.

Cc: Russell King 
Cc: Arnd Bergmann 
Cc: Lecopzer Chen 
Cc: Oleg Nesterov 
Cc: linux-arm-kernel@lists.infradead.org
Fixes: 4e57a4ddf6b0 ("ARM: 9107/1: syscall: always store thread_info->abi_syscall")
Reviewed-by: Arnd Bergmann 
Link: https://lore.kernel.org/r/20230810195422.2304827-2-keescook@chromium.org
Signed-off-by: Kees Cook

ARM: kernel: Get rid of thread_info::used_cp[] array

2023-05-17T13:08:22+00:00

We keep track of which coprocessor triggered a fault in the used_cp[]
array in thread_info, but this data is never used anywhere. So let's
remove it.

Linus did some digging and found out that the last user of this field
was removed in commit bb1a773d5b6b ("kill unused dump_fpu() instances").

Reviewed-by: Linus Walleij 
Signed-off-by: Ard Biesheuvel

arm: ptrace: user_regset_copyin_ignore() always returns 0

2022-11-15T22:30:39+00:00

user_regset_copyin_ignore() always returns 0, so checking its result seems
pointless -- don't do this anymore...

Link: https://lkml.kernel.org/r/20221014212235.10770-3-s.shtylyov@omp.ru
Signed-off-by: Sergey Shtylyov 
Cc: Brian Cain 
Cc: Catalin Marinas 
Cc: Christophe Leroy 
Cc: David S. Miller 
Cc: Dinh Nguyen 
Cc: Helge Deller 
Cc: James Bottomley 
Cc: Jonas Bonn 
Cc: Michael Ellerman 
Cc: Nicholas Piggin 
Cc: Oleg Nesterov 
Cc: Rich Felker 
Cc: Russell King 
Cc: Stafford Horne 
Cc: Stefan Kristiansson 
Cc: Thomas Bogendoerfer 
Cc: Will Deacon 
Cc: Yoshinori Sato 
Signed-off-by: Andrew Morton

ptrace: Create ptrace_report_syscall_{entry,exit} in ptrace.h

2022-03-10T19:35:08+00:00

Rename tracehook_report_syscall_{entry,exit} to
ptrace_report_syscall_{entry,exit} and place them in ptrace.h

There is no longer any generic tracehook infractructure so make
these ptrace specific functions ptrace specific.

Reviewed-by: Kees Cook 
Link: https://lkml.kernel.org/r/20220309162454.123006-3-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman"

ptrace/arm: Rename tracehook_report_syscall report_syscall

2022-03-10T19:34:09+00:00

Make the arm and arm64 code more concise and less confusing by
renaming the architecture specific tracehook_report_syscall to
report_syscall.

Reviewed-by: Kees Cook 
Link: https://lkml.kernel.org/r/20220309162454.123006-2-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman"

Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm

2021-09-09T20:25:49+00:00

Pull ARM development updates from Russell King:

 - Rename "mod_init" and "mod_exit" so that initcall debug output is
   actually useful (Randy Dunlap)

 - Update maintainers entries for linux-arm-kernel to indicate it is
   moderated for non-subscribers (Randy Dunlap)

 - Move install rules to arch/arm/Makefile (Masahiro Yamada)

 - Drop unnecessary ARCH_NR_GPIOS definition (Linus Walleij)

 - Don't warn about atags_to_fdt() stack size (David Heidelberg)

 - Speed up unaligned copy_{from,to}_kernel_nofault (Arnd Bergmann)

 - Get rid of set_fs() usage (Arnd Bergmann)

 - Remove checks for GCC prior to v4.6 (Geert Uytterhoeven)

* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: 9118/1: div64: Remove always-true __div64_const32_is_OK() duplicate
  ARM: 9117/1: asm-generic: div64: Remove always-true __div64_const32_is_OK()
  ARM: 9116/1: unified: Remove check for gcc < 4
  ARM: 9110/1: oabi-compat: fix oabi epoll sparse warning
  ARM: 9113/1: uaccess: remove set_fs() implementation
  ARM: 9112/1: uaccess: add __{get,put}_kernel_nofault
  ARM: 9111/1: oabi-compat: rework fcntl64() emulation
  ARM: 9114/1: oabi-compat: rework sys_semtimedop emulation
  ARM: 9108/1: oabi-compat: rework epoll_wait/epoll_pwait emulation
  ARM: 9107/1: syscall: always store thread_info->abi_syscall
  ARM: 9109/1: oabi-compat: add epoll_pwait handler
  ARM: 9106/1: traps: use get_kernel_nofault instead of set_fs()
  ARM: 9115/1: mm/maccess: fix unaligned copy_{from,to}_kernel_nofault
  ARM: 9105/1: atags_to_fdt: don't warn about stack size
  ARM: 9103/1: Drop ARCH_NR_GPIOS definition
  ARM: 9102/1: move theinstall rules to arch/arm/Makefile
  ARM: 9100/1: MAINTAINERS: mark all linux-arm-kernel@infradead list as moderated
  ARM: 9099/1: crypto: rename 'mod_init' & 'mod_exit' functions to be module-specific

ARM: 9107/1: syscall: always store thread_info->abi_syscall

2021-08-20T10:39:26+00:00

The system call number is used in a a couple of places, in particular
ptrace, seccomp and /proc//syscall.

The last one apparently never worked reliably on ARM for tasks that are
not currently getting traced.

Storing the syscall number in the normal entry path makes it work,
as well as allowing us to see if the current system call is for OABI
compat mode, which is the next thing I want to hook into.

Since the thread_info->syscall field is not just the number any more, it
is now renamed to abi_syscall. In kernels that enable both OABI and EABI,
the upper bits of this field encode 0x900000 (__NR_OABI_SYSCALL_BASE)
for OABI tasks, while normal EABI tasks do not set the upper bits. This
makes it possible to implement the in_oabi_syscall() helper later.

All other users of thread_info->syscall go through the syscall_get_nr()
helper, which in turn filters out the ABI bits.

Note that the ABI information is lost with PTRACE_SET_SYSCALL, so one
cannot set the internal number to a particular version, but this was
already the case. We could change it to let gdb encode the ABI type along
with the syscall in a CONFIG_OABI_COMPAT-enabled kernel, but that itself
would be a (backwards-compatible) ABI change, so I don't do it here.

Acked-by: Christoph Hellwig 
Signed-off-by: Arnd Bergmann 
Signed-off-by: Russell King (Oracle)

ARM: ep93xx: remove MaverickCrunch support

2021-08-04T11:30:04+00:00

The MaverickCrunch support for ep93xx never made it into glibc and
was removed from gcc in its 4.8 release in 2012. It is now one of
the last parts of arch/arm/ that fails to build with the clang
integrated assembler, which is unlikely to ever want to support it.

The two alternatives are to force the use of binutils/gas when
building the crunch support, or to remove it entirely.

According to Hartley Sweeten:

 "Martin Guy did a lot of work trying to get the maverick crunch working
  but I was never able to successfully use it for anything. It "kind"
  of works but depending on the EP93xx silicon revision there are still
  a number of hardware bugs that either give imprecise or garbage results.

  I have no problem with removing the kernel support for the maverick
  crunch."

Unless someone else comes up with a good reason to keep it around,
remove it now. This touches mostly the ep93xx platform, but removes
a bit of code from ARM common ptrace and signal frame handling as well.

If there are remaining users of MaverickCrunch, they can use LTS
kernels for at least another five years before kernel support ends.

Link: https://lore.kernel.org/linux-arm-kernel/20210802141245.1146772-1-arnd@kernel.org/
Link: https://lore.kernel.org/linux-arm-kernel/20210226164345.3889993-1-arnd@kernel.org/
Link: https://github.com/ClangBuiltLinux/linux/issues/1272
Link: https://gcc.gnu.org/legacy-ml/gcc/2008-03/msg01063.html
Cc: "Martin Guy" 
Signed-off-by: Arnd Bergmann

arm: switch to ->regset_get()

2020-07-27T18:31:09+00:00

Signed-off-by: Al Viro