kernel.git/arch/powerpc/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

powerpc: improve handling of unrecoverable system reset

2021-03-17T15:34:30Z

[ Upstream commit 11cb0a25f71818ca7ab4856548ecfd83c169aa4d ] If an unrecoverable system reset hits in process context, the system does not have to panic. Similar to machine check, call nmi_exit() before die(). Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210130130852.2952424-26-npiggin@gmail.com Signed-off-by: Sasha Levin

powerpc/traps: Make unrecoverable NMIs die instead of panic

2020-10-01T11:12:44Z

[ Upstream commit 265d6e588d87194c2fe2d6c240247f0264e0c19b ] System Reset and Machine Check interrupts that are not recoverable due to being nested or interrupting when RI=0 currently panic. This is not necessary, and can often just kill the current context and recover. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Reviewed-by: Christophe Leroy Link: https://lore.kernel.org/r/20200508043408.886394-16-npiggin@gmail.com Signed-off-by: Sasha Levin

powerpc/traps: Fix the message printed when stack overflows

2019-03-23T13:35:27Z

commit 9bf3d3c4e4fd82c7174f4856df372ab2a71005b9 upstream. Today's message is useless: [ 42.253267] Kernel stack overflow in process (ptrval), r1=c65500b0 This patch fixes it: [ 66.905235] Kernel stack overflow in process sh[356], r1=c65560b0 Fixes: ad67b74d2469 ("printk: hash addresses printed with %p") Cc: stable@vger.kernel.org # v4.15+ Signed-off-by: Christophe Leroy [mpe: Use task_pid_nr()] Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman

powerpc/traps: fix recoverability of machine check handling on book3s/32

2019-03-23T13:35:27Z

commit 0bbea75c476b77fa7d7811d6be911cc7583e640f upstream. Looks like book3s/32 doesn't set RI on machine check, so checking RI before calling die() will always be fatal allthought this is not an issue in most cases. Fixes: b96672dd840f ("powerpc: Machine check interrupt is a non-maskable interrupt") Fixes: daf00ae71dad ("powerpc/traps: restore recoverability of machine_check interrupts") Signed-off-by: Christophe Leroy Cc: stable@vger.kernel.org Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman

powerpc/traps: restore recoverability of machine_check interrupts

2018-11-21T08:24:02Z

[ Upstream commit daf00ae71dad8aa05965713c62558aeebf2df48e ] commit b96672dd840f ("powerpc: Machine check interrupt is a non- maskable interrupt") added a call to nmi_enter() at the beginning of machine check restart exception handler. Due to that, in_interrupt() always returns true regardless of the state before entering the exception, and die() panics even when the system was not already in interrupt. This patch calls nmi_exit() before calling die() in order to restore the interrupt state we had before calling nmi_enter() Fixes: b96672dd840f ("powerpc: Machine check interrupt is a non-maskable interrupt") Signed-off-by: Christophe Leroy Reviewed-by: Nicholas Piggin Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

powerpc/64s: sreset panic if there is no debugger or crash dump handlers

2018-05-30T05:52:26Z

[ Upstream commit d40b6768e45bd9213139b2d91d30c7692b6007b1 ] system_reset_exception does most of its own crash handling now, invoking the debugger or crash dumps if they are registered. If not, then it goes through to die() to print stack traces, and then is supposed to panic (according to comments). However after die() prints oopses, it does its own handling which doesn't allow system_reset_exception to panic (e.g., it may just kill the current process). This patch causes sreset exceptions to return from die after it prints messages but before acting. This also stops die from invoking the debugger on 0x100 crashes. system_reset_exception similarly calls the debugger. It had been thought this was harmless (because if the debugger was disabled, neither call would fire, and if it was enabled the first call would return). However in some cases like xmon 'X' command, the debugger returns 0, which currently causes it to be entered again (first in system_reset_exception, then in die), which is confusing. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

powerpc/fscr: Enable interrupts earlier before calling get_user()

2018-05-30T05:52:23Z

[ Upstream commit 709b973c844c0b4d115ac3a227a2e5a68722c912 ] The function get_user() can sleep while trying to fetch instruction from user address space and causes the following warning from the scheduler. BUG: sleeping function called from invalid context Though interrupts get enabled back but it happens bit later after get_user() is called. This change moves enabling these interrupts earlier covering the function get_user(). While at this, lets check for kernel mode and crash as this interrupt should not have been triggered from the kernel context. Signed-off-by: Anshuman Khandual Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

powerpc: System reset avoid interleaving oops using die synchronisation

2018-04-26T09:02:06Z

[ Upstream commit 4552d128c26e0f0f27a5bd2fadc24092b8f6c1d7 ] The die() oops path contains a serializing lock to prevent oops messages from being interleaved. In the case of a system reset initiated oops (e.g., qemu nmi command), __die was being called which lacks that synchronisation and oops reports could be interleaved across CPUs. A recent patch 4388c9b3a6ee7 ("powerpc: Do not send system reset request through the oops path") changed this to __die to avoid the debugger() call, but there is no real harm to calling it twice if the first time fell through. So go back to using die() here. This was observed to fix the problem. Fixes: 4388c9b3a6ee7 ("powerpc: Do not send system reset request through the oops path") Signed-off-by: Nicholas Piggin Reviewed-by: David Gibson Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/scottwood/linux into fixes

2017-09-20T10:05:24Z

Merge one commit from Scott which I missed while away.