On 13.12.20 23:55, Linus Walleij wrote:
> The Ux500 platforms have some memory carveouts set aside for
> communicating with the modem and for the initial secure software
> (ISSW). These areas are protected by the memory controller
> and will result in an external abort if accessed like common
> read/write memory.
>
> On the legacy boot loaders, these were set aside by using
> cmdline arguments such as this:
>
> mem=96M@0 mem_mtrace=15M@96M mem_mshared=1M@111M
> mem_modem=16M@112M mali.mali_mem=32M@128M mem=96M@160M
> hwmem=127M@256M mem_issw=1M@383M mem_ram_console=1M@384M
> mem=638M@385M
>
> Reserve the relevant areas in the device tree instead. The
> "mali", "hwmem", "mem_ram_console" and the trailing 1MB at the
> end of the memory reservations in the list are not relevant for
> the upstream kernel as these are nowadays replaced with
> upstream technologies such as CMA. The modem and ISSW
> reservations are necessary.
>
> This was manifested in a bug that surfaced in response to
> commit 7fef431be9c9 ("mm/page_alloc: place pages to tail in __free_pages_core()")
> which changes the behaviour of memory allocations
> in such a way that the platform will sooner run into these
> dangerous areas, with "Unhandled fault: imprecise external
> abort (0xc06) at 0xb6fd83dc" or similar: the real reason
> turns out to be that the PTE is pointing right into one of
> the reserved memory areas. We were just lucky until now.
>
> We need to augment the DB8500 and DB8520 SoCs similarly
> and also create a new include for the DB9500 used in the
> Snowball since this does not have a modem and thus does
> not need the modem memory reservation, albeit it needs
> the ISSW reservation.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Cc: David Hildenbrand <david@xxxxxxxxxx>
> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
> ---
> ARM SoC folks: please apply this directly for fixes.
Can we come up with a Fixes: tag or has this been broken forever?
(assuming modern boot loaders)
>
> David: just FYI if you run into more of these type of
> regressions. Actually the patch is unintentionally good
> at smoking out other bugs :D
Thanks for CCing - I'm adding some people that ran into similar issues,
but not sure if the other bugreports are related (or have similar root
causes).
Thanks a lot!
> ---
> arch/arm/boot/dts/ste-db8500.dtsi | 38 ++++++++++++++++++++++++++++++
> arch/arm/boot/dts/ste-db8520.dtsi | 38 ++++++++++++++++++++++++++++++
> arch/arm/boot/dts/ste-db9500.dtsi | 35 +++++++++++++++++++++++++++
> arch/arm/boot/dts/ste-snowball.dts | 2 +-
> 4 files changed, 112 insertions(+), 1 deletion(-)
> create mode 100644 arch/arm/boot/dts/ste-db9500.dtsi
>
> diff --git a/arch/arm/boot/dts/ste-db8500.dtsi b/arch/arm/boot/dts/ste-db8500.dtsi
> index d309fad32229..344d29853bf7 100644
> --- a/arch/arm/boot/dts/ste-db8500.dtsi
> +++ b/arch/arm/boot/dts/ste-db8500.dtsi
> @@ -12,4 +12,42 @@ cpu@300 {
> 200000 0>;
> };
> };
> +
> + reserved-memory {
> + #address-cells = <1>;
> + #size-cells = <1>;
> + ranges;
> +
> + /* Modem trace memory */
> + ram@06000000 {
> + reg = <0x06000000 0x00f00000>;
> + no-map;
> + };
> +
> + /* Modem shared memory */
> + ram@06f00000 {
> + reg = <0x06f00000 0x00100000>;
> + no-map;
> + };
> +
> + /* Modem private memory */
> + ram@07000000 {
> + reg = <0x07000000 0x01000000>;
> + no-map;
> + };
> +
> + /*
> + * Initial Secure Software ISSW memory
> + *
> + * This is probably only used if the kernel tries
> + * to actually call into trustzone to run secure
> + * applications, which the mainline kernel probably
> + * will not do on this old chipset. But you can never
> + * be too careful, so reserve this memory anyway.
> + */
> + ram@17f00000 {
> + reg = <0x17f00000 0x00100000>;
> + no-map;
> + };
> + };
> };
> diff --git a/arch/arm/boot/dts/ste-db8520.dtsi b/arch/arm/boot/dts/ste-db8520.dtsi
> index 48bd8728ae27..287804e9e183 100644
> --- a/arch/arm/boot/dts/ste-db8520.dtsi
> +++ b/arch/arm/boot/dts/ste-db8520.dtsi
> @@ -12,4 +12,42 @@ cpu@300 {
> 200000 0>;
> };
> };
> +
> + reserved-memory {
> + #address-cells = <1>;
> + #size-cells = <1>;
> + ranges;
> +
> + /* Modem trace memory */
> + ram@06000000 {
> + reg = <0x06000000 0x00f00000>;
> + no-map;
> + };
> +
> + /* Modem shared memory */
> + ram@06f00000 {
> + reg = <0x06f00000 0x00100000>;
> + no-map;
> + };
> +
> + /* Modem private memory */
> + ram@07000000 {
> + reg = <0x07000000 0x01000000>;
> + no-map;
> + };
> +
> + /*
> + * Initial Secure Software ISSW memory
> + *
> + * This is probably only used if the kernel tries
> + * to actually call into trustzone to run secure
> + * applications, which the mainline kernel probably
> + * will not do on this old chipset. But you can never
> + * be too careful, so reserve this memory anyway.
> + */
> + ram@17f00000 {
> + reg = <0x17f00000 0x00100000>;
> + no-map;
> + };
> + };
> };
> diff --git a/arch/arm/boot/dts/ste-db9500.dtsi b/arch/arm/boot/dts/ste-db9500.dtsi
> new file mode 100644
> index 000000000000..0afff703191c
> --- /dev/null
> +++ b/arch/arm/boot/dts/ste-db9500.dtsi
> @@ -0,0 +1,35 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +
> +#include "ste-dbx5x0.dtsi"
> +
> +/ {
> + cpus {
> + cpu@300 {
> + /* cpufreq controls */
> + operating-points = <1152000 0
> + 800000 0
> + 400000 0
> + 200000 0>;
> + };
> + };
> +
> + reserved-memory {
> + #address-cells = <1>;
> + #size-cells = <1>;
> + ranges;
> +
> + /*
> + * Initial Secure Software ISSW memory
> + *
> + * This is probably only used if the kernel tries
> + * to actually call into trustzone to run secure
> + * applications, which the mainline kernel probably
> + * will not do on this old chipset. But you can never
> + * be too careful, so reserve this memory anyway.
> + */
> + ram@17f00000 {
> + reg = <0x17f00000 0x00100000>;
> + no-map;
> + };
> + };
> +};
> diff --git a/arch/arm/boot/dts/ste-snowball.dts b/arch/arm/boot/dts/ste-snowball.dts
> index be90e73c923e..27d8a07718a0 100644
> --- a/arch/arm/boot/dts/ste-snowball.dts
> +++ b/arch/arm/boot/dts/ste-snowball.dts
> @@ -4,7 +4,7 @@
> */
>
> /dts-v1/;
> -#include "ste-db8500.dtsi"
> +#include "ste-db9500.dtsi"
> #include "ste-href-ab8500.dtsi"
> #include "ste-href-family-pinctrl.dtsi"
>
>
--
Thanks,
David / dhildenb
