[PATCH 3/3] MIPS: KASLR: Make relocation_address can be configured

From: Jinyang He
Date: Wed Nov 18 2020 - 21:29:33 EST


When CONFIG_RANDOMIZE_BASE is not set, determine_relocation_address()
always returns a constant. It is not friendly to users if the address
cannot be used. Make it can be configured at Kconfig.

Signed-off-by: Jinyang He <hejinyang@xxxxxxxxxxx>
---
arch/mips/Kconfig | 5 +++++
arch/mips/kernel/relocate.c | 2 +-
2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 1508829..1c95478 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -2803,6 +2803,11 @@ config RELOCATION_TABLE_SIZE

If unsure, leave at the default value.

+config RELOCATE_DESTINATION
+ hex "Relocate address when RANDOMIZE_BASE is not set"
+ depends on RELOCATABLE && !RANDOMIZE_BASE
+ default "0xffffffff81000000"
+
config RANDOMIZE_BASE
bool "Randomize the address of the kernel image"
depends on RELOCATABLE
diff --git a/arch/mips/kernel/relocate.c b/arch/mips/kernel/relocate.c
index 709cfa0..b7ea6ff 100644
--- a/arch/mips/kernel/relocate.c
+++ b/arch/mips/kernel/relocate.c
@@ -276,7 +276,7 @@ static inline void __init *determine_relocation_address(void)
* Choose a new address for the kernel
* For now we'll hard code the destination
*/
- return (void *)0xffffffff81000000;
+ return (void *)CONFIG_RELOCATE_DESTINATION;
}

#endif
--
2.1.0