diff options
| author | Will Deacon <will@kernel.org> | 2019-08-27 14:36:38 +0100 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2019-08-27 17:37:02 +0100 |
| commit | 5b1cfe3a0ba74c1f2b83b607712a217b9f9463a2 (patch) | |
| tree | fa5c90257088a8c00e134e3dbe1a14dc5ee1447e /arch | |
| parent | 0e1645557d19fc6d88d3c40431f63a3c3a4c417b (diff) | |
| download | linux-5b1cfe3a0ba74c1f2b83b607712a217b9f9463a2.tar.bz2 | |
arm64: smp: Don't enter kernel with NULL stack pointer or task struct
Although SMP bringup is inherently racy, we can significantly reduce
the window during which secondary CPUs can unexpectedly enter the
kernel by sanity checking the 'stack' and 'task' fields of the
'secondary_data' structure. If the booting CPU gave up waiting for us,
then they will have been cleared to NULL and we should spin in a WFE; WFI
loop instead.
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/kernel/head.S | 8 | ||||
| -rw-r--r-- | arch/arm64/kernel/smp.c | 1 |
2 files changed, 9 insertions, 0 deletions
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 2cdacd1c141b..0baadf335172 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -724,14 +724,22 @@ __secondary_switched: adr_l x0, secondary_data ldr x1, [x0, #CPU_BOOT_STACK] // get secondary_data.stack + cbz x1, __secondary_too_slow mov sp, x1 ldr x2, [x0, #CPU_BOOT_TASK] + cbz x2, __secondary_too_slow msr sp_el0, x2 mov x29, #0 mov x30, #0 b secondary_start_kernel ENDPROC(__secondary_switched) +__secondary_too_slow: + wfe + wfi + b __secondary_too_slow +ENDPROC(__secondary_too_slow) + /* * The booting CPU updates the failed status @__early_cpu_boot_status, * with MMU turned off. diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index 63c7a7682e93..1f8aeb77cba5 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -136,6 +136,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle) secondary_data.task = NULL; secondary_data.stack = NULL; + __flush_dcache_area(&secondary_data, sizeof(secondary_data)); status = READ_ONCE(secondary_data.status); if (ret && status) { |