kernel.git/arch/powerpc/include/asm/interrupt.h, branch linux-6.10.y

powerpc: Avoid nmi_enter/nmi_exit in real mode interrupt.

2024-04-15T02:55:48Z

nmi_enter()/nmi_exit() touches per cpu variables which can lead to kernel crash when invoked during real mode interrupt handling (e.g. early HMI/MCE interrupt handler) if percpu allocation comes from vmalloc area. Early HMI/MCE handlers are called through DEFINE_INTERRUPT_HANDLER_NMI() wrapper which invokes nmi_enter/nmi_exit calls. We don't see any issue when percpu allocation is from the embedded first chunk. However with CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK enabled there are chances where percpu allocation can come from the vmalloc area. With kernel command line "percpu_alloc=page" we can force percpu allocation to come from vmalloc area and can see kernel crash in machine_check_early: [ 1.215714] NIP [c000000000e49eb4] rcu_nmi_enter+0x24/0x110 [ 1.215717] LR [c0000000000461a0] machine_check_early+0xf0/0x2c0 [ 1.215719] --- interrupt: 200 [ 1.215720] [c000000fffd73180] [0000000000000000] 0x0 (unreliable) [ 1.215722] [c000000fffd731b0] [0000000000000000] 0x0 [ 1.215724] [c000000fffd73210] [c000000000008364] machine_check_early_common+0x134/0x1f8 Fix this by avoiding use of nmi_enter()/nmi_exit() in real mode if percpu first chunk is not embedded. Reviewed-by: Christophe Leroy Tested-by: Shirisha Ganta Signed-off-by: Mahesh Salgaonkar Signed-off-by: Michael Ellerman Link: https://msgid.link/20240410043006.81577-1-mahesh@linux.ibm.com

powerpc: Use user_mode() macro when possible

2024-02-22T10:55:33Z

There is a nice macro to check user mode. Use it instead of open coding anding with MSR_PR to increase readability and avoid having to comment what that anding is for. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://msgid.link/fbf74887dcf1f1ba9e1680fc3247cbb581b00662.1708078228.git.christophe.leroy@csgroup.eu

powerpc: Consolidate 32-bit and 64-bit interrupt_enter_prepare

2023-02-10T11:17:35Z

There are two separeate implementations for 32-bit and 64-bit which mostly do the same thing. Consolidating on one implementation ends up being smaller and simpler, there is just irq soft-mask reconcile that is specific to 64-bit. There should be no real functional change with this patch, but it does make the context tracking calls necessary for 32-bit to support context tracking. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20230121095805.2823731-2-npiggin@gmail.com

powerpc/64s: Add missing declaration for machine_check_early_boot()

2022-11-25T13:25:32Z

There's no declaration for machine_check_early_boot(), which leads to a build failure with W=1. Add one. Fixes: 2f5182cffa43 ("powerpc/64s: early boot machine check handler") Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221125132521.2167039-1-mpe@ellerman.id.au

powerpc/64/interrupt: avoid BUG/WARN recursion in interrupt entry

2022-09-28T09:22:11Z

BUG/WARN are handled with a program interrupt which can turn into an infinite recursion when there are bugs in interrupt handler entry (which can be irritated by bugs in other parts of the code). There is one feeble attempt to avoid this recursion, but it misses several cases. Make a tidier macro for this and switch most bugs in the interrupt entry wrapper over to use it. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220926054305.2671436-7-npiggin@gmail.com

powerpc/64/interrupt: Fix false warning in context tracking due to idle state

2022-09-28T09:22:11Z

Commit 171476775d32 ("context_tracking: Convert state to atomic_t") added a CONTEXT_IDLE state which can be encountered by interrupts from kernel mode in the idle thread, causing a false positive warning. Fixes: 171476775d32 ("context_tracking: Convert state to atomic_t") Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220926054305.2671436-2-npiggin@gmail.com

powerpc: Change system_call_exception calling convention

2022-09-28T09:22:09Z

Change system_call_exception arguments to pass a pointer to a stack frame container caller state, as well as the original r0, which determines the number of the syscall. This has been observed to yield improved performance to passing them by registers, circumventing the need to allocate a stack frame. Signed-off-by: Rohan McLure Reviewed-by: Nicholas Piggin [mpe: Retain clearing of high bits of args for compat tasks] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220921065605.1051927-21-rmclure@linux.ibm.com

powerpc: Remove CONFIG_PPC_BOOK3E

2022-09-26T13:00:13Z

CONFIG_PPC_BOOK3E is redundant with CONFIG_PPC_BOOK3E_64. The later is more explicit about the fact that it's a 64 bits target. Remove CONFIG_PPC_BOOK3E. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/5d0891490813c19cdcfc04678f512ea68cba3e64.1663606876.git.christophe.leroy@csgroup.eu

powerpc: Include asm/firmware.h in all users of firmware_has_feature()

2022-06-29T06:45:05Z

Trying to remove asm/ppc_asm.h from all places that don't need it leads to several failures linked to firmware_has_feature(). To fix it, include asm/firmware.h in all files using firmware_has_feature() All users found with: git grep -L "firmware\.h" ` git grep -l "firmware_has_feature("` Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/11956ec181a034b51a881ac9c059eea72c679a73.1651828453.git.christophe.leroy@csgroup.eu

powerpc/kasan: Don't instrument non-maskable or raw interrupts

2022-05-22T05:58:29Z

Disable address sanitization for raw and non-maskable interrupt handlers, because they can run in real mode, where we cannot access the shadow memory. (Note that kasan_arch_is_ready() doesn't test for real mode, since it is a static branch for speed, and in any case not all the entry points to the generic KASAN code are protected by kasan_arch_is_ready guards.) The changes to interrupt_nmi_enter/exit_prepare() look larger than they actually are. The changes are equivalent to adding !IS_ENABLED(CONFIG_KASAN) to the conditions for calling nmi_enter() or nmi_exit() in real mode. That is, the code is equivalent to using the following condition for calling nmi_enter/exit: if (((!IS_ENABLED(CONFIG_PPC_BOOK3S_64) || !firmware_has_feature(FW_FEATURE_LPAR) || radix_enabled()) && !IS_ENABLED(CONFIG_KASAN) || (mfmsr() & MSR_DR)) That unwieldy condition has been split into several statements with comments, for easier reading. The nmi_ipi_lock functions that call atomic functions (i.e., nmi_ipi_lock_start(), nmi_ipi_lock() and nmi_ipi_unlock()), besides being marked noinstr, now call arch_atomic_* functions instead of atomic_* functions because with KASAN enabled, the atomic_* functions are wrappers which explicitly do address sanitization on their arguments. Since we are trying to avoid address sanitization, we have to use the lower-level arch_atomic_* versions. In hv_nmi_check_nonrecoverable(), the regs_set_unrecoverable() call has been open-coded so as to avoid having to either trust the inlining or mark regs_set_unrecoverable() as noinstr. [paulus@ozlabs.org: combined a few work-in-progress commits of Daniel's and wrote the commit message.] Signed-off-by: Daniel Axtens Signed-off-by: Paul Mackerras Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/YoTFGaKM8Pd46PIK@cleo