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arch/riscv: add support for detecting null pointer exception using PMP

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This change uses a PMP slot to implement null pointer detection.

Signed-off-by: Dino Li <Dino.Li@ite.com.tw>
This commit is contained in:
Dino Li 2023-05-23 11:55:43 +08:00 committed by Anas Nashif
parent b64cfe9832
commit 252d68ff9f
2 changed files with 32 additions and 0 deletions
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21
arch/riscv/Kconfig
View File

@ -261,6 +261,27 @@ config PMP_STACK_GUARD_MIN_SIZE
wiggle room to accommodate the eventual overflow exception
stack usage.
# Implement the null pointer detection using the Physical Memory Protection
# (PMP) Unit.
config NULL_POINTER_EXCEPTION_DETECTION_PMP
bool "Use PMP for null pointer exception detection"
depends on RISCV_PMP
help
Null pointer dereference detection implemented
using PMP functionality.
if NULL_POINTER_EXCEPTION_DETECTION_PMP
config NULL_POINTER_EXCEPTION_REGION_SIZE
hex "Inaccessible region to implement null pointer detection"
default 0x10
help
Use a PMP slot to make region (starting at address 0x0) inaccessible for
detecting null pointer dereferencing (raising a CPU access fault).
Minimum is 4 bytes.
endif # NULL_POINTER_EXCEPTION_DETECTION_PMP
endmenu
config MAIN_STACK_SIZE

11
arch/riscv/core/pmp.c
View File

@ -330,6 +330,17 @@ void z_riscv_pmp_init(void)
(size_t)__rom_region_size,
pmp_addr, pmp_cfg, ARRAY_SIZE(pmp_addr));
#ifdef CONFIG_NULL_POINTER_EXCEPTION_DETECTION_PMP
/*
* Use a PMP slot to make region (starting at address 0x0) inaccessible
* for detecting null pointer dereferencing.
*/
set_pmp_entry(&index, PMP_NONE | PMP_L,
0,
CONFIG_NULL_POINTER_EXCEPTION_REGION_SIZE,
pmp_addr, pmp_cfg, ARRAY_SIZE(pmp_addr));
#endif
#ifdef CONFIG_PMP_STACK_GUARD
/*
* Set the stack guard for this CPU's IRQ stack by making the bottom