lkml.org 
[lkml]   [2018]   [Nov]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
SubjectRe: [PATCH 5/5] efi: permit calling efi_mem_reserve_persistent from atomic context
From
Date
Hi Ard,


On 11/14/2018 11:55 AM, Ard Biesheuvel wrote:
> Currently, efi_mem_reserve_persistent() may not be called from atomic
> context, since both the kmalloc() call and the memremap() call may
> sleep.
>
> The kmalloc() call is easy enough to fix, but the memremap() call
> needs to be moved into an init hook since we cannot control the
> memory allocation behavior of memremap() at the call site.

So, at first glance this looks correct until I noticed that
its_cpu_init_lpis() is being called before the early_initcalls are run.

This results in the WARN_ON triggering with the following backtrace:

[ 0.000000] its_cpu_init_lpis+0x1d4/0x2e0
[ 0.000000] its_cpu_init+0x78/0x1b4
[ 0.000000] gic_init_bases+0x2c4/0x2e0
[ 0.000000] gic_acpi_init+0x158/0x270
[ 0.000000] acpi_match_madt+0x4c/0x84
[ 0.000000] acpi_table_parse_entries_array+0x140/0x218
[ 0.000000] acpi_table_parse_entries+0x70/0x98
[ 0.000000] acpi_table_parse_madt+0x40/0x50
[ 0.000000] __acpi_probe_device_table+0x88/0xe0
[ 0.000000] irqchip_init+0x38/0x40
[ 0.000000] init_IRQ+0xfc/0x130
[ 0.000000] start_kernel+0x344/0x4cc

due to the efi_memreserve_root not yet being set.



>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
> drivers/firmware/efi/efi.c | 31 +++++++++++++++++++------------
> 1 file changed, 19 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index 72a4da76d274..fad7c62cfc0e 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -967,36 +967,43 @@ bool efi_is_table_address(unsigned long phys_addr)
> }
>
> static DEFINE_SPINLOCK(efi_mem_reserve_persistent_lock);
> +static struct linux_efi_memreserve *efi_memreserve_root __ro_after_init;
>
> int efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
> {
> - struct linux_efi_memreserve *rsv, *parent;
> + struct linux_efi_memreserve *rsv;
>
> - if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR)
> + if (!efi_memreserve_root)
> return -ENODEV;
>
> - rsv = kmalloc(sizeof(*rsv), GFP_KERNEL);
> + rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC);
> if (!rsv)
> return -ENOMEM;
>
> - parent = memremap(efi.mem_reserve, sizeof(*rsv), MEMREMAP_WB);
> - if (!parent) {
> - kfree(rsv);
> - return -ENOMEM;
> - }
> -
> rsv->base = addr;
> rsv->size = size;
>
> spin_lock(&efi_mem_reserve_persistent_lock);
> - rsv->next = parent->next;
> - parent->next = __pa(rsv);
> + rsv->next = efi_memreserve_root->next;
> + efi_memreserve_root->next = __pa(rsv);
> spin_unlock(&efi_mem_reserve_persistent_lock);
>
> - memunmap(parent);
> + return 0;
> +}
>
> +static int __init efi_memreserve_root_init(void)
> +{
> + if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR)
> + return -ENODEV;
> +
> + efi_memreserve_root = memremap(efi.mem_reserve,
> + sizeof(*efi_memreserve_root),
> + MEMREMAP_WB);
> + if (!efi_memreserve_root)
> + return -ENOMEM;
> return 0;
> }
> +early_initcall(efi_memreserve_root_init);
>
> #ifdef CONFIG_KEXEC
> static int update_efi_random_seed(struct notifier_block *nb,
>

\
 
 \ /
  Last update: 2018-11-27 19:59    [W:0.081 / U:3.688 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site