On 05/21/2018 04:44 AM, Russell King wrote:
> Check for CPU bugs when secondary processors are being brought online,
> and also when CPUs are resuming from a low power mode. This gives an
> opportunity to check that processor specific bug workarounds are
> correctly enabled for all paths that a CPU re-enters the kernel.
>
> Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
> Reviewed-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
Something I missed, is that this correctly warns about e.g: missing the
IBE bit for secondary cores, but it seems to be missing it for the boot CPU:
[ 0.001053] CPU: Testing write buffer coherency: ok
[ 0.001086] CPU: Spectre v2: using ICIALLU workaround
[ 0.001304] CPU0: update cpu_capacity 1024
[ 0.001316] CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
[ 0.001693] Setting up static identity map for 0x200000 - 0x200060
[ 0.001769] Hierarchical SRCU implementation.
[ 0.003951] brcmstb: biuctrl: MCP: Write pairing already disabled
[ 0.004224] smp: Bringing up secondary CPUs ...
[ 0.004874] CPU1: update cpu_capacity 1024
[ 0.004877] CPU1: thread -1, cpu 1, socket 0, mpidr 80000001
[ 0.004881] CPU1: Spectre v2: firmware did not set auxiliary control
register IBE bit, system vulnerable
[ 0.005604] CPU2: update cpu_capacity 1024
[ 0.005607] CPU2: thread -1, cpu 2, socket 0, mpidr 80000002
[ 0.005610] CPU2: Spectre v2: firmware did not set auxiliary control
register IBE bit, system vulnerable
[ 0.006295] CPU3: update cpu_capacity 1024
[ 0.006299] CPU3: thread -1, cpu 3, socket 0, mpidr 80000003
[ 0.006302] CPU3: Spectre v2: firmware did not set auxiliary control
register IBE bit, system vulnerable
[ 0.006377] smp: Brought up 1 node, 4 CPUs
[ 0.006389] SMP: Total of 4 processors activated (216.00 BogoMIPS).
[ 0.006398] CPU: All CPU(s) started in SVC mode.
Which could be confusing if you intentionally restricted a SMP system to
UP with maxcpus=1 or smp=off:
[ 0.001043] CPU: Testing write buffer coherency: ok
[ 0.001077] CPU: Spectre v2: using ICIALLU workaround
[ 0.001291] CPU0: update cpu_capacity 1024
[ 0.001302] CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
[ 0.001516] Setting up static identity map for 0x200000 - 0x200060
[ 0.001593] Hierarchical SRCU implementation.
[ 0.003829] brcmstb: biuctrl: MCP: Write pairing already disabled
[ 0.004097] smp: Bringing up secondary CPUs ...
[ 0.004108] smp: Brought up 1 node, 1 CPU
[ 0.004117] SMP: Total of 1 processors activated (54.00 BogoMIPS).
[ 0.004126] CPU: All CPU(s) started in SVC mode.
> ---
> arch/arm/include/asm/bugs.h | 2 ++
> arch/arm/kernel/bugs.c | 5 +++++
> arch/arm/kernel/smp.c | 4 ++++
> arch/arm/kernel/suspend.c | 2 ++
> 4 files changed, 13 insertions(+)
>
> diff --git a/arch/arm/include/asm/bugs.h b/arch/arm/include/asm/bugs.h
> index ed122d294f3f..73a99c72a930 100644
> --- a/arch/arm/include/asm/bugs.h
> +++ b/arch/arm/include/asm/bugs.h
> @@ -14,8 +14,10 @@ extern void check_writebuffer_bugs(void);
>
> #ifdef CONFIG_MMU
> extern void check_bugs(void);
> +extern void check_other_bugs(void);
> #else
> #define check_bugs() do { } while (0)
> +#define check_other_bugs() do { } while (0)
> #endif
>
> #endif
> diff --git a/arch/arm/kernel/bugs.c b/arch/arm/kernel/bugs.c
> index 88024028bb70..16e7ba2a9cc4 100644
> --- a/arch/arm/kernel/bugs.c
> +++ b/arch/arm/kernel/bugs.c
> @@ -3,7 +3,12 @@
> #include <asm/bugs.h>
> #include <asm/proc-fns.h>
>
> +void check_other_bugs(void)
> +{
> +}
> +
> void __init check_bugs(void)
> {
> check_writebuffer_bugs();
> + check_other_bugs();
> }
> diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
> index 2da087926ebe..5ad0b67b9e33 100644
> --- a/arch/arm/kernel/smp.c
> +++ b/arch/arm/kernel/smp.c
> @@ -31,6 +31,7 @@
> #include <linux/irq_work.h>
>
> #include <linux/atomic.h>
> +#include <asm/bugs.h>
> #include <asm/smp.h>
> #include <asm/cacheflush.h>
> #include <asm/cpu.h>
> @@ -405,6 +406,9 @@ asmlinkage void secondary_start_kernel(void)
> * before we continue - which happens after __cpu_up returns.
> */
> set_cpu_online(cpu, true);
> +
> + check_other_bugs();
> +
> complete(&cpu_running);
>
> local_irq_enable();
> diff --git a/arch/arm/kernel/suspend.c b/arch/arm/kernel/suspend.c
> index a40ebb7c0896..d08099269e35 100644
> --- a/arch/arm/kernel/suspend.c
> +++ b/arch/arm/kernel/suspend.c
> @@ -3,6 +3,7 @@
> #include <linux/slab.h>
> #include <linux/mm_types.h>
>
> +#include <asm/bugs.h>
> #include <asm/cacheflush.h>
> #include <asm/idmap.h>
> #include <asm/pgalloc.h>
> @@ -36,6 +37,7 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
> cpu_switch_mm(mm->pgd, mm);
> local_flush_bp_all();
> local_flush_tlb_all();
> + check_other_bugs();
> }
>
> return ret;
>
--
Florian
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