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linux-stable/arch/riscv
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Alexandre Ghiti 311cd2f6e2
riscv: Fix set_memory_XX() and set_direct_map_XX() by splitting huge linear mappings 
When STRICT_KERNEL_RWX is set, any change of permissions on any kernel
mapping (vmalloc/modules/kernel text...etc) should be applied on its
linear mapping alias. The problem is that the riscv kernel uses huge
mappings for the linear mapping and walk_page_range_novma() does not
split those huge mappings.

So this patchset implements such split in order to apply fine-grained
permissions on the linear mapping.

Below is the difference before and after (the first PUD mapping is split
into PTE/PMD mappings):

Before:

---[ Linear mapping ]---
0xffffaf8000080000-0xffffaf8000200000    0x0000000080080000      1536K PTE     D A G . . W R V
0xffffaf8000200000-0xffffaf8077c00000    0x0000000080200000      1914M PMD     D A G . . W R V
0xffffaf8077c00000-0xffffaf8078800000    0x00000000f7c00000        12M PMD     D A G . . . R V
0xffffaf8078800000-0xffffaf8078c00000    0x00000000f8800000         4M PMD     D A G . . W R V
0xffffaf8078c00000-0xffffaf8079200000    0x00000000f8c00000         6M PMD     D A G . . . R V
0xffffaf8079200000-0xffffaf807e600000    0x00000000f9200000        84M PMD     D A G . . W R V
0xffffaf807e600000-0xffffaf807e716000    0x00000000fe600000      1112K PTE     D A G . . W R V
0xffffaf807e717000-0xffffaf807e71a000    0x00000000fe717000        12K PTE     D A G . . W R V
0xffffaf807e71d000-0xffffaf807e71e000    0x00000000fe71d000         4K PTE     D A G . . W R V
0xffffaf807e722000-0xffffaf807e800000    0x00000000fe722000       888K PTE     D A G . . W R V
0xffffaf807e800000-0xffffaf807fe00000    0x00000000fe800000        22M PMD     D A G . . W R V
0xffffaf807fe00000-0xffffaf807ff54000    0x00000000ffe00000      1360K PTE     D A G . . W R V
0xffffaf807ff55000-0xffffaf8080000000    0x00000000fff55000       684K PTE     D A G . . W R V
0xffffaf8080000000-0xffffaf8400000000    0x0000000100000000        14G PUD     D A G . . W R V

After:

---[ Linear mapping ]---
0xffffaf8000080000-0xffffaf8000200000    0x0000000080080000      1536K PTE     D A G . . W R V
0xffffaf8000200000-0xffffaf8077c00000    0x0000000080200000      1914M PMD     D A G . . W R V
0xffffaf8077c00000-0xffffaf8078800000    0x00000000f7c00000        12M PMD     D A G . . . R V
0xffffaf8078800000-0xffffaf8078a00000    0x00000000f8800000         2M PMD     D A G . . W R V
0xffffaf8078a00000-0xffffaf8078c00000    0x00000000f8a00000         2M PTE     D A G . . W R V
0xffffaf8078c00000-0xffffaf8079200000    0x00000000f8c00000         6M PMD     D A G . . . R V
0xffffaf8079200000-0xffffaf807e600000    0x00000000f9200000        84M PMD     D A G . . W R V
0xffffaf807e600000-0xffffaf807e716000    0x00000000fe600000      1112K PTE     D A G . . W R V
0xffffaf807e717000-0xffffaf807e71a000    0x00000000fe717000        12K PTE     D A G . . W R V
0xffffaf807e71d000-0xffffaf807e71e000    0x00000000fe71d000         4K PTE     D A G . . W R V
0xffffaf807e722000-0xffffaf807e800000    0x00000000fe722000       888K PTE     D A G . . W R V
0xffffaf807e800000-0xffffaf807fe00000    0x00000000fe800000        22M PMD     D A G . . W R V
0xffffaf807fe00000-0xffffaf807ff54000    0x00000000ffe00000      1360K PTE     D A G . . W R V
0xffffaf807ff55000-0xffffaf8080000000    0x00000000fff55000       684K PTE     D A G . . W R V
0xffffaf8080000000-0xffffaf8080800000    0x0000000100000000         8M PMD     D A G . . W R V
0xffffaf8080800000-0xffffaf8080af6000    0x0000000100800000      3032K PTE     D A G . . W R V
0xffffaf8080af6000-0xffffaf8080af8000    0x0000000100af6000         8K PTE     D A G . X . R V
0xffffaf8080af8000-0xffffaf8080c00000    0x0000000100af8000      1056K PTE     D A G . . W R V
0xffffaf8080c00000-0xffffaf8081a00000    0x0000000100c00000        14M PMD     D A G . . W R V
0xffffaf8081a00000-0xffffaf8081a40000    0x0000000101a00000       256K PTE     D A G . . W R V
0xffffaf8081a40000-0xffffaf8081a44000    0x0000000101a40000        16K PTE     D A G . X . R V
0xffffaf8081a44000-0xffffaf8081a52000    0x0000000101a44000        56K PTE     D A G . . W R V
0xffffaf8081a52000-0xffffaf8081a54000    0x0000000101a52000         8K PTE     D A G . X . R V
...
0xffffaf809e800000-0xffffaf80c0000000    0x000000011e800000       536M PMD     D A G . . W R V
0xffffaf80c0000000-0xffffaf8400000000    0x0000000140000000        13G PUD     D A G . . W R V

Note that this also fixes memfd_secret() syscall which uses
set_direct_map_invalid_noflush() and set_direct_map_default_noflush() to
remove the pages from the linear mapping. Below is the kernel page table
while a memfd_secret() syscall is running, you can see all the !valid
page table entries in the linear mapping:

...
0xffffaf8082240000-0xffffaf8082241000    0x0000000102240000         4K PTE     D A G . . W R .
0xffffaf8082241000-0xffffaf8082250000    0x0000000102241000        60K PTE     D A G . . W R V
0xffffaf8082250000-0xffffaf8082252000    0x0000000102250000         8K PTE     D A G . . W R .
0xffffaf8082252000-0xffffaf8082256000    0x0000000102252000        16K PTE     D A G . . W R V
0xffffaf8082256000-0xffffaf8082257000    0x0000000102256000         4K PTE     D A G . . W R .
0xffffaf8082257000-0xffffaf8082258000    0x0000000102257000         4K PTE     D A G . . W R V
0xffffaf8082258000-0xffffaf8082259000    0x0000000102258000         4K PTE     D A G . . W R .
0xffffaf8082259000-0xffffaf808225a000    0x0000000102259000         4K PTE     D A G . . W R V
0xffffaf808225a000-0xffffaf808225c000    0x000000010225a000         8K PTE     D A G . . W R .
0xffffaf808225c000-0xffffaf8082266000    0x000000010225c000        40K PTE     D A G . . W R V
0xffffaf8082266000-0xffffaf8082268000    0x0000000102266000         8K PTE     D A G . . W R .
0xffffaf8082268000-0xffffaf8082284000    0x0000000102268000       112K PTE     D A G . . W R V
0xffffaf8082284000-0xffffaf8082288000    0x0000000102284000        16K PTE     D A G . . W R .
0xffffaf8082288000-0xffffaf808229c000    0x0000000102288000        80K PTE     D A G . . W R V
0xffffaf808229c000-0xffffaf80822a0000    0x000000010229c000        16K PTE     D A G . . W R .
0xffffaf80822a0000-0xffffaf80822a5000    0x00000001022a0000        20K PTE     D A G . . W R V
0xffffaf80822a5000-0xffffaf80822a6000    0x00000001022a5000         4K PTE     D A G . . . R V
0xffffaf80822a6000-0xffffaf80822ab000    0x00000001022a6000        20K PTE     D A G . . W R V
...

And when the memfd_secret() fd is released, the linear mapping is
correctly reset:

...
0xffffaf8082240000-0xffffaf80822a5000    0x0000000102240000       404K PTE     D A G . . W R V
0xffffaf80822a5000-0xffffaf80822a6000    0x00000001022a5000         4K PTE     D A G . . . R V
0xffffaf80822a6000-0xffffaf80822af000    0x00000001022a6000        36K PTE     D A G . . W R V
...

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20231108075930.7157-3-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-11-08 07:08:33 -08:00
..
boot RISC-V Devicetrees for v6.6 Part 2 2023-08-21 21:47:55 -04:00
configs Kbuild updates for v6.6 2023-09-05 11:01:47 -07:00
errata Merge patch series "Add non-coherent DMA support for AX45MP" 2023-09-08 11:24:34 -07:00
include RISC-V Patches for the 6.6 Merge Window, Part 2 (try 2) 2023-09-09 14:25:11 -07:00
kernel Merge patch series "bpf, riscv: use BPF prog pack allocator in BPF JIT" 2023-09-08 11:25:25 -07:00
kvm KVM/riscv changes for 6.6 2023-08-31 13:25:55 -04:00
lib riscv: uaccess: Return the number of bytes effectively not copied 2023-08-16 07:30:06 -07:00
mm riscv: Fix set_memory_XX() and set_direct_map_XX() by splitting huge linear mappings 2023-11-08 07:08:33 -08:00
net bpf, riscv: use prog pack allocator in the BPF JIT 2023-09-06 06:26:07 -07:00
purgatory riscv/purgatory: Disable CFI 2023-08-23 14:16:40 -07:00
tools riscv: Check relocations at compile time 2023-04-19 07:46:32 -07:00
Kbuild kexec: rename ARCH_HAS_KEXEC_PURGATORY 2023-08-18 10:18:54 -07:00
Kconfig riscv: Kconfig: Select DMA_DIRECT_REMAP only if MMU is enabled 2023-09-08 11:25:26 -07:00
Kconfig.debug
Kconfig.errata riscv: Kconfig.errata: Add dependency for RISCV_SBI in ERRATA_ANDES config 2023-09-08 11:25:28 -07:00
Kconfig.socs RISC-V: make ARCH_THEAD preclude XIP_KERNEL 2023-07-05 22:21:23 +02:00
Makefile riscv: Require FRAME_POINTER for some configurations 2023-08-23 09:07:26 -07:00
Makefile.postlink riscv: Use --emit-relocs in order to move .rela.dyn in init 2023-04-19 07:46:33 -07:00