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Mark Rutland 7d9e8f71b9 arm64: avoid returning from bad_mode 
Generally, taking an unexpected exception should be a fatal event, and
bad_mode is intended to cater for this. However, it should be possible
to contain unexpected synchronous exceptions from EL0 without bringing
the kernel down, by sending a SIGILL to the task.

We tried to apply this approach in commit 9955ac47f4 ("arm64:
don't kill the kernel on a bad esr from el0"), by sending a signal for
any bad_mode call resulting from an EL0 exception.

However, this also applies to other unexpected exceptions, such as
SError and FIQ. The entry paths for these exceptions branch to bad_mode
without configuring the link register, and have no kernel_exit. Thus, if
we take one of these exceptions from EL0, bad_mode will eventually
return to the original user link register value.

This patch fixes this by introducing a new bad_el0_sync handler to cater
for the recoverable case, and restoring bad_mode to its original state,
whereby it calls panic() and never returns. The recoverable case
branches to bad_el0_sync with a bl, and returns to userspace via the
usual ret_to_user mechanism.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Fixes: 9955ac47f4 ("arm64: don't kill the kernel on a bad esr from el0")
Reported-by: Mark Salter <msalter@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: stable@vger.kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2017-01-19 15:38:22 +00:00
..
probes Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
vdso arm64: Add support for CLOCK_MONOTONIC_RAW in clock_gettime() vDSO 2016-07-12 16:06:32 +01:00
.gitignore
acpi.c ACPI / osl: Remove acpi_get_table_with_size()/early_acpi_os_unmap_memory() users 2016-12-21 02:36:38 +01:00
acpi_numa.c arm64/numa: avoid inconsistent information to be printed 2016-09-09 14:59:08 +01:00
acpi_parking_protocol.c arm64: kernel: acpi: fix ioremap in ACPI parking protocol cpu_postboot 2016-02-26 15:39:52 +00:00
alternative.c arm64: alternative: Add support for patching adrp instructions 2016-09-09 15:03:28 +01:00
arm64ksyms.c Merge branch 'for-next/kprobes' into for-next/core 2016-07-21 18:20:41 +01:00
armv8_deprecated.c Merge branch 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-25 14:05:56 -08:00
asm-offsets.c arm64: Introduce uaccess_{disable,enable} functionality based on TTBR0_EL1 2016-11-21 18:48:53 +00:00
cacheinfo.c arm64: simplify sysreg manipulation 2016-09-09 11:43:50 +01:00
cpu-reset.h arm64: Add back cpu reset routines 2016-06-27 16:31:25 +01:00
cpu-reset.S arm64: Add back cpu reset routines 2016-06-27 16:31:25 +01:00
cpu_errata.c arm64: cpufeature: Schedule enable() calls instead of calling them via IPI 2016-10-20 09:50:53 +01:00
cpu_ops.c arm64: apply __ro_after_init to some objects 2016-08-22 12:32:29 +01:00
cpufeature.c arm64: Introduce uaccess_{disable,enable} functionality based on TTBR0_EL1 2016-11-21 18:48:53 +00:00
cpuidle.c arm64: add support for ACPI Low Power Idle(LPI) 2016-07-21 23:29:38 +02:00
cpuinfo.c arm64/cpuinfo: Convert to hotplug state machine 2016-12-02 00:52:38 +01:00
debug-monitors.c cpu/hotplug: Cleanup state names 2016-12-25 10:47:44 +01:00
efi-entry.S arm64: move early boot code to the .init segment 2016-04-14 18:11:30 +01:00
efi.c arm64: mm: replace 'block_mappings_allowed' with 'page_mappings_only' 2016-11-07 18:15:04 +00:00
entry-fpsimd.S
entry-ftrace.S ftrace: Remove CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST from config 2016-08-24 12:15:13 +02:00
entry.S arm64: avoid returning from bad_mode 2017-01-19 15:38:22 +00:00
entry32.S arm64: entry32: remove pointless register assignment 2015-07-10 16:47:13 +01:00
fpsimd.c arm64: Support systems without FP/ASIMD 2016-11-16 18:05:10 +00:00
ftrace.c ftrace: Add return address pointer to ftrace_ret_stack 2016-08-24 12:15:14 +02:00
head.S arm64: head.S: Fix CNTHCTL_EL2 access on VHE system 2016-11-29 11:37:05 +00:00
hibernate-asm.S arm64: Introduce raw_{d,i}cache_line_size 2016-09-09 15:03:29 +01:00
hibernate.c treewide: Fix printk() message errors 2016-12-14 10:54:27 +01:00
hw_breakpoint.c cpu/hotplug: Cleanup state names 2016-12-25 10:47:44 +01:00
hyp-stub.S arm64: Add back cpu reset routines 2016-06-27 16:31:25 +01:00
image.h arm64 updates for 4.7: 2016-05-16 17:17:24 -07:00
insn.c arm64: Get rid of asm/opcodes.h 2016-12-02 10:56:21 +00:00
io.c arm64: optimize memcpy_{from,to}io() and memset_io() 2014-11-06 17:25:27 +00:00
irq.c arm64: remove irq_count and do_softirq_own_stack() 2015-12-21 17:26:01 +00:00
jump_label.c jump_label: Rename JUMP_LABEL_{EN,DIS}ABLE to JUMP_LABEL_{JMP,NOP} 2015-08-03 11:34:12 +02:00
kaslr.c arm64: apply __ro_after_init to some objects 2016-08-22 12:32:29 +01:00
kgdb.c arm64: kgdb_step_brk_fn: ignore other's exception 2016-11-07 18:15:20 +00:00
kuser32.S
machine_kexec.c arm64/kexec: Add pr_debug output 2016-06-27 16:31:26 +01:00
Makefile arm64: Set UTS_MACHINE in the Makefile 2016-08-31 12:31:38 +01:00
module-plts.c arm64: add support for module PLTs 2016-02-24 14:57:24 +00:00
module.c arm64: add support for kernel ASLR 2016-02-24 14:57:27 +00:00
module.lds arm64: add support for module PLTs 2016-02-24 14:57:24 +00:00
paravirt.c arm64: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops 2015-12-21 14:40:54 +00:00
pci.c PCI/ACPI: Extend pci_mcfg_lookup() to return ECAM config accessors 2016-12-06 13:45:48 -06:00
perf_callchain.c perf core: Add a 'nr' field to perf_event_callchain_context 2016-05-16 23:11:51 -03:00
perf_event.c KVM: arm64: Fix the issues when guest PMCCFILTR is configured 2016-11-18 09:06:58 +00:00
perf_regs.c perf: Move task_pt_regs sampling into arch code 2015-01-09 11:12:28 +01:00
process.c arm64: Add hypervisor safe helper for checking constant capabilities 2016-11-16 17:50:51 +00:00
psci.c ARM: 8511/1: ARM64: kernel: PSCI: move PSCI idle management code to drivers/firmware 2016-02-11 15:33:38 +00:00
ptrace.c arm64/ptrace: Reject attempts to set incomplete hardware breakpoint fields 2017-01-18 18:05:12 +00:00
relocate_kernel.S arm64: Introduce raw_{d,i}cache_line_size 2016-09-09 15:03:29 +01:00
return_address.c arm64: factor out current_stack_pointer 2016-11-11 18:25:43 +00:00
setup.c arm64: setup: introduce kaslr_offset() 2016-12-20 09:48:46 -08:00
signal.c arm64: Add uprobe support 2016-11-07 18:15:21 +00:00
signal32.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
sleep.S arm64: move sp_el0 and tpidr_el1 into cpu_suspend_ctx 2016-11-11 18:25:44 +00:00
smccc-call.S ARM: 8480/2: arm64: add implementation for arm-smccc 2016-01-04 16:24:45 +00:00
smp.c arm64: split thread_info from task stack 2016-11-11 18:25:46 +00:00
smp_spin_table.c arm64: vmlinux.ld: Add mmuoff data sections and move mmuoff text into idmap 2016-08-25 18:00:30 +01:00
stacktrace.c arm64: prep stack walkers for THREAD_INFO_IN_TASK 2016-11-11 18:25:44 +00:00
suspend.c arm64: move sp_el0 and tpidr_el1 into cpu_suspend_ctx 2016-11-11 18:25:44 +00:00
sys.c arm64: compat: Check for AArch32 state 2016-04-20 12:22:42 +01:00
sys32.c arm64: fix implementation of mmap2 compat syscall 2015-03-19 10:43:51 +00:00
sys_compat.c arm64: simplify sysreg manipulation 2016-09-09 11:43:50 +01:00
time.c arm64: ftrace: fix a stack tracer's output under function graph tracer 2015-12-21 17:26:02 +00:00
topology.c arm64: add sysfs cpu_capacity attribute 2016-11-07 18:15:03 +00:00
trace-events-emulation.h arm64: Trace emulation of AArch32 legacy instructions 2014-11-20 16:35:02 +00:00
traps.c arm64: avoid returning from bad_mode 2017-01-19 15:38:22 +00:00
vdso.c arm/arm64: arch_timer: Use archdata to indicate vdso suitability 2016-09-23 17:19:25 +01:00
vmlinux.lds.S arm64: Introduce uaccess_{disable,enable} functionality based on TTBR0_EL1 2016-11-21 18:48:53 +00:00