kernel.git/arch/arm64/kernel/traps.c, branch linux-4.14.y

exit: Add and use make_task_dead.

2023-02-06T06:46:33Z

commit 0e25498f8cd43c1b5aa327f373dd094e9a006da7 upstream. There are two big uses of do_exit. The first is it's design use to be the guts of the exit(2) system call. The second use is to terminate a task after something catastrophic has happened like a NULL pointer in kernel code. Add a function make_task_dead that is initialy exactly the same as do_exit to cover the cases where do_exit is called to handle catastrophic failure. In time this can probably be reduced to just a light wrapper around do_task_dead. For now keep it exactly the same so that there will be no behavioral differences introducing this new concept. Replace all of the uses of do_exit that use it for catastraphic task cleanup with make_task_dead to make it clear what the code is doing. As part of this rename rewind_stack_do_exit rewind_stack_and_make_dead. Signed-off-by: "Eric W. Biederman" Signed-off-by: Eric Biggers Signed-off-by: Greg Kroah-Hartman

arm64: traps: Don't print stack or raw PC/LR values in backtraces

2020-04-24T06:01:03Z

[ Upstream commit a25ffd3a6302a67814280274d8f1aa4ae2ea4b59 ] Printing raw pointer values in backtraces has potential security implications and are of questionable value anyway. This patch follows x86's lead and removes the "Exception stack:" dump from kernel backtraces, as well as converting PC/LR values to symbols such as "sysrq_handle_crash+0x20/0x30". Tested-by: Laura Abbott Signed-off-by: Will Deacon Signed-off-by: Lee Jones Signed-off-by: Greg Kroah-Hartman

arm64: fix for bad_mode() handler to always result in panic

2019-12-01T08:14:19Z

commit e4ba15debcfd27f60d43da940a58108783bff2a6 upstream. The bad_mode() handler is called if we encounter an uunknown exception, with the expectation that the subsequent call to panic() will halt the system. Unfortunately, if the exception calling bad_mode() is taken from EL0, then the call to die() can end up killing the current user task and calling schedule() instead of falling through to panic(). Remove the die() call altogether, since we really want to bring down the machine in this "impossible" case. Signed-off-by: Hari Vyas Signed-off-by: Will Deacon Signed-off-by: Catalin Marinas Signed-off-by: Lee Jones Signed-off-by: Greg Kroah-Hartman

arm64: capabilities: Update prototype for enable call back

2019-10-29T08:17:12Z

[ Upstream commit c0cda3b8ee6b4b6851b2fd8b6db91fd7b0e2524a ] We issue the enable() call back for all CPU hwcaps capabilities available on the system, on all the CPUs. So far we have ignored the argument passed to the call back, which had a prototype to accept a "void *" for use with on_each_cpu() and later with stop_machine(). However, with commit 0a0d111d40fd1 ("arm64: cpufeature: Pass capability structure to ->enable callback"), there are some users of the argument who wants the matching capability struct pointer where there are multiple matching criteria for a single capability. Clean up the declaration of the call back to make it clear. 1) Renamed to cpu_enable(), to imply taking necessary actions on the called CPU for the entry. 2) Pass const pointer to the capability, to allow the call back to check the entry. (e.,g to check if any action is needed on the CPU) 3) We don't care about the result of the call back, turning this to a void. Cc: Will Deacon Cc: Catalin Marinas Cc: Mark Rutland Cc: Andre Przywara Cc: James Morse Acked-by: Robin Murphy Reviewed-by: Julien Thierry Signed-off-by: Dave Martin [suzuki: convert more users, rename call back and drop results] Signed-off-by: Suzuki K Poulose Signed-off-by: Will Deacon Signed-off-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman

arm64: only advance singlestep for user instruction traps

2019-05-08T05:20:45Z

commit 9478f1927e6ef9ef5e1ad761af1c98aa8e40b7f5 upstream. Our arm64_skip_faulting_instruction() helper advances the userspace singlestep state machine, but this is also called by the kernel BRK handler, as used for WARN*(). Thus, if we happen to hit a WARN*() while the user singlestep state machine is in the active-no-pending state, we'll advance to the active-pending state without having executed a user instruction, and will take a step exception earlier than expected when we return to userspace. Let's fix this by only advancing the state machine when skipping a user instruction. Signed-off-by: Mark Rutland Cc: Andrey Konovalov Cc: Catalin Marinas Cc: Will Deacon Signed-off-by: Will Deacon Signed-off-by: Andrey Konovalov Signed-off-by: Greg Kroah-Hartman

arm64: Fix single stepping in kernel traps

2019-05-08T05:20:45Z

commit 6436beeee5721a8e906e9eabf866f12d04470437 upstream. Software Step exception is missing after stepping a trapped instruction. Ensure SPSR.SS gets set to 0 after emulating/skipping a trapped instruction before doing ERET. Cc: Catalin Marinas Cc: Mark Rutland Signed-off-by: Julien Thierry Reviewed-by: Alex Bennée [will: replaced AARCH32_INSN_SIZE with 4] Signed-off-by: Will Deacon Signed-off-by: Andrey Konovalov Signed-off-by: Greg Kroah-Hartman

arm64: backtrace: Don't bother trying to unwind the userspace stack

2019-04-17T06:37:54Z

commit 1e6f5440a6814d28c32d347f338bfef68bc3e69d upstream. Calling dump_backtrace() with a pt_regs argument corresponding to userspace doesn't make any sense and our unwinder will simply print "Call trace:" before unwinding the stack looking for user frames. Rather than go through this song and dance, just return early if we're passed a user register state. Cc: Fixes: 1149aad10b1e ("arm64: Add dump_backtrace() in show_regs") Reported-by: Kefeng Wang Signed-off-by: Will Deacon Signed-off-by: Greg Kroah-Hartman

arm64: Disable unhandled signal log messages by default

2018-02-28T09:19:42Z

commit 5ee39a71fd89ab7240c5339d04161c44a8e03269 upstream. aarch64 unhandled signal kernel messages are very verbose, suggesting them to be more of a debugging aid: sigsegv[33]: unhandled level 2 translation fault (11) at 0x00000000, esr 0x92000046, in sigsegv[400000+71000] CPU: 1 PID: 33 Comm: sigsegv Tainted: G W 4.15.0-rc3+ #3 Hardware name: linux,dummy-virt (DT) pstate: 60000000 (nZCv daif -PAN -UAO) pc : 0x4003f4 lr : 0x4006bc sp : 0000fffffe94a060 x29: 0000fffffe94a070 x28: 0000000000000000 x27: 0000000000000000 x26: 0000000000000000 x25: 0000000000000000 x24: 00000000004001b0 x23: 0000000000486ac8 x22: 00000000004001c8 x21: 0000000000000000 x20: 0000000000400be8 x19: 0000000000400b30 x18: 0000000000484728 x17: 000000000865ffc8 x16: 000000000000270f x15: 00000000000000b0 x14: 0000000000000002 x13: 0000000000000001 x12: 0000000000000000 x11: 0000000000000000 x10: 0008000020008008 x9 : 000000000000000f x8 : ffffffffffffffff x7 : 0004000000000000 x6 : ffffffffffffffff x5 : 0000000000000000 x4 : 0000000000000000 x3 : 00000000004003e4 x2 : 0000fffffe94a1e8 x1 : 000000000000000a x0 : 0000000000000000 Disable them by default, so they can be enabled using /proc/sys/debug/exception-trace. Cc: Signed-off-by: Michael Weiser Signed-off-by: Will Deacon Signed-off-by: Greg Kroah-Hartman

arm64: Remove unimplemented syscall log message

2018-02-28T09:19:42Z

commit 1962682d2b2fbe6cfa995a85c53c069fadda473e upstream. Stop printing a (ratelimited) kernel message for each instance of an unimplemented syscall being called. Userland making an unimplemented syscall is not necessarily misbehaviour and to be expected with a current userland running on an older kernel. Also, the current message looks scary to users but does not actually indicate a real problem nor help them narrow down the cause. Just rely on sys_ni_syscall() to return -ENOSYS. Cc: Acked-by: Will Deacon Signed-off-by: Michael Weiser Signed-off-by: Will Deacon Signed-off-by: Greg Kroah-Hartman

arm64: ensure __dump_instr() checks addr_limit

2017-11-02T18:33:08Z

It's possible for a user to deliberately trigger __dump_instr with a chosen kernel address. Let's avoid problems resulting from this by using get_user() rather than __get_user(), ensuring that we don't erroneously access kernel memory. Where we use __dump_instr() on kernel text, we already switch to KERNEL_DS, so this shouldn't adversely affect those cases. Fixes: 60ffc30d5652810d ("arm64: Exception handling") Cc: stable@vger.kernel.org Acked-by: Will Deacon Signed-off-by: Mark Rutland Signed-off-by: Catalin Marinas