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rpi3: add RPI3_RUNTIME_UART build option 

Some OSes (e.g. Ubuntu 18.04 LTS on Raspberry Pi 3) may disable the
runtime UART in a manner that prevents the system from rebooting if
ATF tries to send runtime messages there.

Also, we don't want the firmware to share the UART with normal
world, as this can be a DoS attack vector into the secure world.

This patch fixes these 2 issues by introducing new build option
RPI3_RUNTIME_UART, that disables the runtime UART by default.

Fixes ARM-software/tf-issues#647

Signed-off-by: Pete Batard <pete@akeo.ie>
This commit is contained in:
Pete Batard 2018-11-13 13:14:26 +00:00
parent 9793e0356e
commit 6d5c61de74
3 changed files with 14 additions and 2 deletions
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4
docs/plat/rpi3.rst
View File

@ -231,6 +231,10 @@ The following build options are supported:
``RPI3_DIRECT_LINUX_BOOT=1``. This option allows to specify the location of a
DTB in memory.
- ``RPI3_RUNTIME_UART``: Indicates whether the UART should be used at runtime
or disabled. ``-1`` (default) disables the runtime UART. Any other value
enables the default UART (currently UART1) for runtime messages.
- ``BL32``: This port can load and run OP-TEE. The OP-TEE image is optional.
Please use the code from `here <https://github.com/OP-TEE/optee_os>`__.
Build the Trusted Firmware with option ``BL32=tee-header_v2.bin

5
plat/rpi3/platform.mk
View File

@ -109,6 +109,10 @@ RPI3_BL33_IN_AARCH32 := 0
# Assume that BL33 isn't the Linux kernel by default
RPI3_DIRECT_LINUX_BOOT := 0
# UART to use at runtime. -1 means the runtime UART is disabled.
# Any other value means the default UART will be used.
RPI3_RUNTIME_UART := -1
# BL32 location
RPI3_BL32_RAM_LOCATION := tdram
ifeq (${RPI3_BL32_RAM_LOCATION}, tsram)
@ -126,6 +130,7 @@ $(eval $(call add_define,RPI3_BL32_RAM_LOCATION_ID))
$(eval $(call add_define,RPI3_BL33_IN_AARCH32))
$(eval $(call add_define,RPI3_DIRECT_LINUX_BOOT))
$(eval $(call add_define,RPI3_PRELOADED_DTB_BASE))
$(eval $(call add_define,RPI3_RUNTIME_UART))
# Verify build config
# -------------------

7
plat/rpi3/rpi3_common.c
View File

@ -96,6 +96,10 @@ static console_16550_t rpi3_console;
void rpi3_console_init(void)
{
int console_scope = CONSOLE_FLAG_BOOT;
#if RPI3_RUNTIME_UART != -1
console_scope |= CONSOLE_FLAG_RUNTIME;
#endif
int rc = console_16550_register(PLAT_RPI3_UART_BASE,
PLAT_RPI3_UART_CLK_IN_HZ,
PLAT_RPI3_UART_BAUDRATE,
@ -109,8 +113,7 @@ void rpi3_console_init(void)
panic();
}
console_set_scope(&rpi3_console.console,
CONSOLE_FLAG_BOOT | CONSOLE_FLAG_RUNTIME);
console_set_scope(&rpi3_console.console, console_scope);
}
/*******************************************************************************