Re: [PATCH] mm, kasan: don't poison boot memory

[Mike Rapoport <rppt@linux.ibm.com>]

Hi George,

On Thu, Feb 25, 2021 at 08:19:18PM -0500, George Kennedy wrote:
> 
> Mike,
> 
> To get rid of the 0x00000000BE453000 hardcoding, I added the following patch
> to your above patch to get the iBFT table "address" to use with
> memblock_reserve():
> 
> diff --git a/drivers/acpi/acpica/tbfind.c b/drivers/acpi/acpica/tbfind.c
> index 56d81e4..4bc7bf3 100644
> --- a/drivers/acpi/acpica/tbfind.c
> +++ b/drivers/acpi/acpica/tbfind.c
> @@ -120,3 +120,34 @@
>      (void)acpi_ut_release_mutex(ACPI_MTX_TABLES);
>      return_ACPI_STATUS(status);
>  }
> +
> +acpi_physical_address
> +acpi_tb_find_table_address(char *signature)
> +{
> +    acpi_physical_address address = 0;
> +    struct acpi_table_desc *table_desc;
> +    int i;
> +
> +    ACPI_FUNCTION_TRACE(tb_find_table_address);
> +
> +printk(KERN_ERR "XXX acpi_tb_find_table_address: signature=%s\n",
> signature);
> +
> +    (void)acpi_ut_acquire_mutex(ACPI_MTX_TABLES);
> +    for (i = 0; i < acpi_gbl_root_table_list.current_table_count; ++i) {
> +        if (memcmp(&(acpi_gbl_root_table_list.tables[i].signature),
> +               signature, ACPI_NAMESEG_SIZE)) {
> +
> +            /* Not the requested table */
> +
> +            continue;
> +        }
> +
> +        /* Table with matching signature has been found */
> +        table_desc = &acpi_gbl_root_table_list.tables[i];
> +        address = table_desc->address;
> +    }
> +
> +    (void)acpi_ut_release_mutex(ACPI_MTX_TABLES);
> +printk(KERN_ERR "XXX acpi_tb_find_table_address(EXIT): address=%llx\n",
> address);
> +    return address;
> +}
> diff --git a/drivers/firmware/iscsi_ibft_find.c
> b/drivers/firmware/iscsi_ibft_find.c
> index 95fc1a6..0de70b4 100644
> --- a/drivers/firmware/iscsi_ibft_find.c
> +++ b/drivers/firmware/iscsi_ibft_find.c
> @@ -28,6 +28,8 @@
> 
>  #include <asm/mmzone.h>
> 
> +extern acpi_physical_address acpi_tb_find_table_address(char *signature);
> +
>  /*
>   * Physical location of iSCSI Boot Format Table.
>   */
> @@ -116,24 +118,32 @@ void __init reserve_ibft_region(void)
>  {
>      struct acpi_table_ibft *table;
>      unsigned long size;
> +    acpi_physical_address address;
> 
>      table = find_ibft();
>      if (!table)
>          return;
> 
>      size = PAGE_ALIGN(table->header.length);
> +    address = acpi_tb_find_table_address(table->header.signature);
>  #if 0
>  printk(KERN_ERR "XXX reserve_ibft_region: table=%llx,
> virt_to_phys(table)=%llx, size=%lx\n",
>      (u64)table, virt_to_phys(table), size);
>      memblock_reserve(virt_to_phys(table), size);
>  #else
> -printk(KERN_ERR "XXX reserve_ibft_region: table=%llx, 0x00000000BE453000,
> size=%lx\n",
> -    (u64)table, size);
> -    memblock_reserve(0x00000000BE453000, size);
> +printk(KERN_ERR "XXX reserve_ibft_region: table=%llx, address=%llx,
> size=%lx\n",
> +    (u64)table, address, size);
> +    if (address)
> +        memblock_reserve(address, size);
> +    else
> +        printk(KERN_ERR "%s: Can't find table address\n", __func__);
>  #endif
> 
> -    if (efi_enabled(EFI_BOOT))
> +    if (efi_enabled(EFI_BOOT)) {
> +printk(KERN_ERR "XXX reserve_ibft_region: calling acpi_put_table(%llx)\n",
> (u64)&table->header);
>          acpi_put_table(&table->header);
> -    else
> +    } else {
>          ibft_addr = table;
> +printk(KERN_ERR "XXX reserve_ibft_region: ibft_addr=%llx\n",
> (u64)ibft_addr);
> +    }
>  }
> 
> Debug from the above:
> [    0.050646] ACPI: Early table checksum verification disabled
> [    0.051778] ACPI: RSDP 0x00000000BFBFA014 000024 (v02 BOCHS )
> [    0.052922] ACPI: XSDT 0x00000000BFBF90E8 00004C (v01 BOCHS BXPCFACP
> 00000001      01000013)
> [    0.054623] ACPI: FACP 0x00000000BFBF5000 000074 (v01 BOCHS BXPCFACP
> 00000001 BXPC 00000001)
> [    0.056326] ACPI: DSDT 0x00000000BFBF6000 00238D (v01 BOCHS BXPCDSDT
> 00000001 BXPC 00000001)
> [    0.058016] ACPI: FACS 0x00000000BFBFD000 000040
> [    0.058940] ACPI: APIC 0x00000000BFBF4000 000090 (v01 BOCHS BXPCAPIC
> 00000001 BXPC 00000001)
> [    0.060627] ACPI: HPET 0x00000000BFBF3000 000038 (v01 BOCHS BXPCHPET
> 00000001 BXPC 00000001)
> [    0.062304] ACPI: BGRT 0x00000000BE49B000 000038 (v01 INTEL EDK2    
> 00000002      01000013)
> [    0.063987] ACPI: iBFT 0x00000000BE453000 000800 (v01 BOCHS BXPCFACP
> 00000000      00000000)
> [    0.065683] XXX acpi_tb_find_table_address: signature=iBFT
> [    0.066754] XXX acpi_tb_find_table_address(EXIT): address=be453000
> [    0.067959] XXX reserve_ibft_region: table=ffffffffff240000,
> address=be453000, size=1000
> [    0.069534] XXX reserve_ibft_region: calling
> acpi_put_table(ffffffffff240000)
> 
> Not sure if it's the right thing to do, but added
> "acpi_tb_find_table_address()" to return the physical address of a table to
> use with memblock_reserve().
> 
> virt_to_phys(table) does not seem to return the physical address for the
> iBFT table (it would be nice if struct acpi_table_header also had a
> "address" element for the physical address of the table).

virt_to_phys() does not work that early because then it is mapped with
early_memremap()  which uses different virtual to physical scheme.

I'd say that acpi_tb_find_table_address() makes sense if we'd like to
reserve ACPI tables outside of drivers/acpi. 

But probably we should simply reserve all the tables during
acpi_table_init() so that any table that firmware put in the normal memory
will be surely reserved.
 
> Ran 10 successful boots with the above without failure.

That's good news indeed :)

> George
> > 
> > 

-- 
Sincerely yours,
Mike.

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