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| author | Karl Mehltretter <kmehltretter@gmail.com> | 2026-07-17 09:16:16 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-07-17 13:03:42 +0200 |
| commit | 782f4dbd1794b4f30dc116a7ca42c5962c409be8 (patch) | |
| tree | 722ce23ce63726aa97a5f61dc7e20bb73ed366e9 | |
| parent | a5ef89f7a8cda4c58bbe3dc68a475d446e5422bc (diff) | |
tty: hvc: restrict HVC_DCC to ARMv6+ and ARM64
hvc_dcc drives the JTAG DCC via the ARMv6/v7 CP14 debug registers
(mrc/mcr p14, 0, rX, c0, c1/c5, 0 in asm/dcc.h). That encoding is
undefined on older ARM cores, and also on ARMv7-M, but HVC_DCC only
depends on ARM, so it can be enabled on e.g. ARM926 (ARCH_MULTI_V5),
where hvc_dcc_console_init() runs __dcc_putchar() at boot and takes an
undefined-instruction trap before the console is up:
Internal error: Oops - undefined instruction: 0 [#1] ARM
PC is at hvc_dcc_check+0x50/0x8c
hvc_dcc_check from hvc_dcc_console_init+0x18/0x48
hvc_dcc_console_init from console_init+0x58/0x170
Kernel panic - not syncing: Fatal exception
Restrict HVC_DCC to the CPUs where that encoding is valid: the
CPU_V6 || CPU_V6K || CPU_V7 set that arch/arm/include/debug/icedcc.S
guards it with, plus ARM64.
Fixes: 16c63f8ea49c ("drivers: char: hvc: add arm JTAG DCC console support")
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20260717071616.91423-1-kmehltretter@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/tty/hvc/Kconfig | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/tty/hvc/Kconfig b/drivers/tty/hvc/Kconfig index c2a4e88b328f..5866195de26a 100644 --- a/drivers/tty/hvc/Kconfig +++ b/drivers/tty/hvc/Kconfig @@ -79,7 +79,7 @@ config HVC_UDBG config HVC_DCC bool "ARM JTAG DCC console" - depends on ARM || ARM64 + depends on (ARM && (CPU_V6 || CPU_V6K || CPU_V7)) || ARM64 select HVC_DRIVER select SERIAL_CORE_CONSOLE help |