| Message ID | 20221115090641.258476-1-bjorn@kernel.org (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 6fdd5d2f8c2f54b7fad4ff4df2a19542aeaf6102 |
| Delegated to: | Palmer Dabbelt |
| Headers | show |
| Series | [v2] riscv: mm: Proper page permissions after initmem free | expand |
| Context | Check | Description |
|---|---|---|
| conchuod/cover_letter | success | Single patches do not need cover letters |
| conchuod/patch_count | success | Link |
| conchuod/tree_selection | success | Guessed tree name to be fixes |
| conchuod/fixes_present | success | Fixes tag present in non-next series |
| conchuod/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| conchuod/dtb_warn_rv64 | success | Errors and warnings before: 0 this patch: 0 |
| conchuod/build_rv32_defconfig | success | Build OK |
| conchuod/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 15 lines checked |
| conchuod/source_inline | success | Was 0 now: 0 |
| conchuod/build_warn_rv64 | success | Errors and warnings before: 0 this patch: 0 |
| conchuod/build_rv64_nommu_k210_defconfig | success | Build OK |
| conchuod/verify_signedoff | success | Signed-off-by tag matches author and committer |
| conchuod/header_inline | success | No static functions without inline keyword in header files |
| conchuod/verify_fixes | success | Fixes tag looks correct |
| conchuod/module_param | success | Was 0 now: 0 |
| conchuod/build_rv64_nommu_virt_defconfig | success | Build OK |
Hi Björn, On 15/11/2022 10:06, Björn Töpel wrote: > From: Björn Töpel <bjorn@rivosinc.com> > > 64-bit RISC-V kernels have the kernel image mapped separately to alias > the linear map. The linear map and the kernel image map are documented > as "direct mapping" and "kernel" respectively in [1]. > > At image load time, the linear map corresponding to the kernel image > is set to PAGE_READ permission, and the kernel image map is set to > PAGE_READ|PAGE_EXEC. > > When the initmem is freed, the pages in the linear map should be > restored to PAGE_READ|PAGE_WRITE, whereas the corresponding pages in > the kernel image map should be restored to PAGE_READ, by removing the > PAGE_EXEC permission. > > This is not the case. For 64-bit kernels, only the linear map is > restored to its proper page permissions at initmem free, and not the > kernel image map. > > In practise this results in that the kernel can potentially jump to > dead __init code, and start executing invalid instructions, without > getting an exception. > > Restore the freed initmem properly, by setting both the kernel image > map to the correct permissions. > > [1] Documentation/riscv/vm-layout.rst > > Fixes: e5c35fa04019 ("riscv: Map the kernel with correct permissions the first time") > Signed-off-by: Björn Töpel <bjorn@rivosinc.com> > --- > v2: * Do not set the kernel image map to PAGE_WRITE. (Alex) > * Massaged the commit message a bit. > > Samuel, I removed your Reviewed-by:/Tested-by: for the v2. > --- > arch/riscv/kernel/setup.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c > index 67ec1fadcfe2..86acd690d529 100644 > --- a/arch/riscv/kernel/setup.c > +++ b/arch/riscv/kernel/setup.c > @@ -322,10 +322,11 @@ subsys_initcall(topology_init); > > void free_initmem(void) > { > - if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)) > - set_kernel_memory(lm_alias(__init_begin), lm_alias(__init_end), > - IS_ENABLED(CONFIG_64BIT) ? > - set_memory_rw : set_memory_rw_nx); > + if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)) { > + set_kernel_memory(lm_alias(__init_begin), lm_alias(__init_end), set_memory_rw_nx); > + if (IS_ENABLED(CONFIG_64BIT)) > + set_kernel_memory(__init_begin, __init_end, set_memory_nx); > + } > > free_initmem_default(POISON_FREE_INITMEM); > } This looks good to me, I tested it on both defconfig and rv32_defconfig on qemu, so you can add: Reviewed-by: Alexandre Ghiti <alex@ghiti.fr> Tested-by: Alexandre Ghiti <alex@ghiti.fr> Thanks, Alex > base-commit: 22dce2b89d6043d5c3f68384285fff5506109317
Hello: This patch was applied to riscv/linux.git (fixes) by Palmer Dabbelt <palmer@rivosinc.com>: On Tue, 15 Nov 2022 10:06:40 +0100 you wrote: > From: Björn Töpel <bjorn@rivosinc.com> > > 64-bit RISC-V kernels have the kernel image mapped separately to alias > the linear map. The linear map and the kernel image map are documented > as "direct mapping" and "kernel" respectively in [1]. > > At image load time, the linear map corresponding to the kernel image > is set to PAGE_READ permission, and the kernel image map is set to > PAGE_READ|PAGE_EXEC. > > [...] Here is the summary with links: - [v2] riscv: mm: Proper page permissions after initmem free https://git.kernel.org/riscv/c/6fdd5d2f8c2f You are awesome, thank you!
diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c index 67ec1fadcfe2..86acd690d529 100644 --- a/arch/riscv/kernel/setup.c +++ b/arch/riscv/kernel/setup.c @@ -322,10 +322,11 @@ subsys_initcall(topology_init); void free_initmem(void) { - if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)) - set_kernel_memory(lm_alias(__init_begin), lm_alias(__init_end), - IS_ENABLED(CONFIG_64BIT) ? - set_memory_rw : set_memory_rw_nx); + if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)) { + set_kernel_memory(lm_alias(__init_begin), lm_alias(__init_end), set_memory_rw_nx); + if (IS_ENABLED(CONFIG_64BIT)) + set_kernel_memory(__init_begin, __init_end, set_memory_nx); + } free_initmem_default(POISON_FREE_INITMEM); }