| Message ID | 20230125082333.1577572-4-alexghiti@rivosinc.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | RISC-V kasan rework | expand |
Hey Alex, On Wed, Jan 25, 2023 at 09:23:30AM +0100, Alexandre Ghiti wrote: > The early virtual address should lie in the kernel address space for > inline kasan instrumentation to succeed, otherwise kasan tries to > dereference an address that does not exist in the address space (since > kasan only maps *kernel* address space, not the userspace). > > Simply use the very first address of the kernel address space for the > early fdt mapping. > > It allowed an Ubuntu kernel to boot successfully with inline > instrumentation. > > Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com> Been poking around in this area the last few days trying to hunt down some bugs... Things look functionally the same w/ this patch and we do get rid of the odd looking pointer which is nice. Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Probably would've made the cause of 50e63dd8ed92 ("riscv: fix reserved memory setup") more difficult to find so glad I got that out of the way well before this patch! Thanks, Conor. > --- > arch/riscv/mm/init.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c > index 478d6763a01a..87f6a5d475a6 100644 > --- a/arch/riscv/mm/init.c > +++ b/arch/riscv/mm/init.c > @@ -57,7 +57,7 @@ unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] > EXPORT_SYMBOL(empty_zero_page); > > extern char _start[]; > -#define DTB_EARLY_BASE_VA PGDIR_SIZE > +#define DTB_EARLY_BASE_VA (ADDRESS_SPACE_END - (PTRS_PER_PGD / 2 * PGDIR_SIZE) + 1) > void *_dtb_early_va __initdata; > uintptr_t _dtb_early_pa __initdata; > > -- > 2.37.2 > >
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index 478d6763a01a..87f6a5d475a6 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -57,7 +57,7 @@ unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] EXPORT_SYMBOL(empty_zero_page); extern char _start[]; -#define DTB_EARLY_BASE_VA PGDIR_SIZE +#define DTB_EARLY_BASE_VA (ADDRESS_SPACE_END - (PTRS_PER_PGD / 2 * PGDIR_SIZE) + 1) void *_dtb_early_va __initdata; uintptr_t _dtb_early_pa __initdata;
The early virtual address should lie in the kernel address space for inline kasan instrumentation to succeed, otherwise kasan tries to dereference an address that does not exist in the address space (since kasan only maps *kernel* address space, not the userspace). Simply use the very first address of the kernel address space for the early fdt mapping. It allowed an Ubuntu kernel to boot successfully with inline instrumentation. Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com> --- arch/riscv/mm/init.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)