linux-kernel - [PATCH v2] ACPI: OSL: Fix the memory mapping of an ACPI GAS that addresses a data structure

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Date:   Mon, 6 Jun 2022 17:16:36 +0800
From:   James Liu <james.liu@....com>
To:     "rafael@...nel.org" <rafael@...nel.org>
Cc:     lenb@...nel.org, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2] ACPI: OSL: Fix the memory mapping of an ACPI GAS that
 addresses a data structure

Hi Rafael, the reported warning (i.e., uninitialized local variable) in V1
by the robot has been fixed. Could you check V2 of this patch? Thanks.

> Subject: [PATCH v2] ACPI: OSL: Fix the memory mapping of an ACPI GAS that addresses a data structure 
>  
> From: James Liu <james.liu@....com>
> 
>     Modify acpi_os_map_generic_address() & acpi_os_unmap_generic_address()
>     to correctly handle cases that a GAS table (i.e., Table 5.1, ACPI 6.4)
>     is used to address a data structure; in the case, the GAS has the field
>     of "Register Bit Width" equal to 0.
> 
>     For example, "Injection Instruction Entry" (Table 18.25, ACPI 6.4) has
>     a RegisterRegion field that is a GAS that points to a data structure
>     SET_ERROR_TYPE_WITH_ADDRESS (Table 18.30), which is required when using
>     EINJ (Error Injection module).
> 
>     This fix preserves a fairly sufficient memory space (i.e. page size) to
>     store the data structure to prevent EINJ module from loading failure if
>     platform firmware can correctly support Injection Instruction Entry in
>     an EINJ table.
> 
> Signed-off-by: James Liu <james.liu@....com>
> ---
>  drivers/acpi/osl.c | 27 +++++++++++++++++++++++----
>  1 file changed, 23 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
> index 45c5c0e45..99f987c8c 100644
> --- a/drivers/acpi/osl.c
> +++ b/drivers/acpi/osl.c
> @@ -452,14 +452,20 @@ EXPORT_SYMBOL_GPL(acpi_os_unmap_memory);
>  
>  void __iomem *acpi_os_map_generic_address(struct acpi_generic_address *gas)
>  {
> -       u64 addr;
> +       u64 addr = 0;
>  
>          if (gas->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY)
>                  return NULL;
>  
> +       /* Handle a case that GAS is used to address an ACPI data structure */
> +       if (!gas->bit_width) {
> +               pr_info("An ACPI data structure at 0x%llx is mapped\n", addr);
> +               return  acpi_os_map_iomem(addr, PAGE_SIZE);
> +       }
> +
>          /* Handle possible alignment issues */
>          memcpy(&addr, &gas->address, sizeof(addr));
> -       if (!addr || !gas->bit_width)
> +       if (!addr)
>                  return NULL;
>  
>          return acpi_os_map_iomem(addr, gas->bit_width / 8);
> @@ -468,15 +474,28 @@ EXPORT_SYMBOL(acpi_os_map_generic_address);
>  
>  void acpi_os_unmap_generic_address(struct acpi_generic_address *gas)
>  {
> -       u64 addr;
> +       u64 addr = 0;
>          struct acpi_ioremap *map;
>  
>          if (gas->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY)
>                  return;
>  
> +       /* Handle a case that GAS is used to address an ACPI data structure */
> +       if (!gas->bit_width) {
> +               pr_info("An ACPI data structure at 0x%llx is unmapped\n", addr);
> +               mutex_lock(&acpi_ioremap_lock);
> +               map = acpi_map_lookup(addr, PAGE_SIZE);
> +               if (!map) {
> +                       mutex_unlock(&acpi_ioremap_lock);
> +                       return;
> +               }
> +               acpi_os_drop_map_ref(map);
> +               mutex_unlock(&acpi_ioremap_lock);
> +       }
> +
>          /* Handle possible alignment issues */
>          memcpy(&addr, &gas->address, sizeof(addr));
> -       if (!addr || !gas->bit_width)
> +       if (!addr)
>                  return;
>  
>          mutex_lock(&acpi_ioremap_lock);
> -- 
> 2.25.1