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authorAlexandre Ghiti <alexghiti@rivosinc.com>2023-04-28 12:29:26 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2023-05-01 08:26:28 +0900
commited96b3143540966e1a730b2583f58779b2dbdbe3 (patch)
tree7ed9c6dc219b737f685ef71c847b52df75c683b5 /Documentation
parent7cb8c95c0a6d6ffedebb815b2bdde849cc98d9c1 (diff)
downloadlinux-ed96b3143540966e1a730b2583f58779b2dbdbe3.tar.gz
riscv: Move early dtb mapping into the fixmap region
commit ef69d2559fe91f23d27a3d6fd640b5641787d22e upstream.

riscv establishes 2 virtual mappings:

- early_pg_dir maps the kernel which allows to discover the system
  memory
- swapper_pg_dir installs the final mapping (linear mapping included)

We used to map the dtb in early_pg_dir using DTB_EARLY_BASE_VA, and this
mapping was not carried over in swapper_pg_dir. It happens that
early_init_fdt_scan_reserved_mem() must be called before swapper_pg_dir is
setup otherwise we could allocate reserved memory defined in the dtb.
And this function initializes reserved_mem variable with addresses that
lie in the early_pg_dir dtb mapping: when those addresses are reused
with swapper_pg_dir, this mapping does not exist and then we trap.

The previous "fix" was incorrect as early_init_fdt_scan_reserved_mem()
must be called before swapper_pg_dir is set up otherwise we could
allocate in reserved memory defined in the dtb.

So move the dtb mapping in the fixmap region which is established in
early_pg_dir and handed over to swapper_pg_dir.

This patch had to be backported because:
- the documentation for sv57 is not present here (as sv48/57 are not
  present)

Fixes: 922b0375fc93 ("riscv: Fix memblock reservation for device tree blob")
Fixes: 8f3a2b4a96dc ("RISC-V: Move DT mapping outof fixmap")
Fixes: 50e63dd8ed92 ("riscv: fix reserved memory setup")
Reported-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/all/f8e67f82-103d-156c-deb0-d6d6e2756f5e@microchip.com/
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230329081932.79831-2-alexghiti@rivosinc.com
Cc: stable@vger.kernel.org # 6.1.x
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/riscv/vm-layout.rst4
1 files changed, 2 insertions, 2 deletions
diff --git a/Documentation/riscv/vm-layout.rst b/Documentation/riscv/vm-layout.rst
index 5b36e45fef60..edb533128712 100644
--- a/Documentation/riscv/vm-layout.rst
+++ b/Documentation/riscv/vm-layout.rst
@@ -47,7 +47,7 @@ RISC-V Linux Kernel SV39
                                                               | Kernel-space virtual memory, shared between all processes:
   ____________________________________________________________|___________________________________________________________
                     |            |                  |         |
-   ffffffc6fee00000 | -228    GB | ffffffc6feffffff |    2 MB | fixmap
+   ffffffc6fea00000 | -228    GB | ffffffc6feffffff |    6 MB | fixmap
    ffffffc6ff000000 | -228    GB | ffffffc6ffffffff |   16 MB | PCI io
    ffffffc700000000 | -228    GB | ffffffc7ffffffff |    4 GB | vmemmap
    ffffffc800000000 | -224    GB | ffffffd7ffffffff |   64 GB | vmalloc/ioremap space
@@ -83,7 +83,7 @@ RISC-V Linux Kernel SV48
                                                               | Kernel-space virtual memory, shared between all processes:
   ____________________________________________________________|___________________________________________________________
                     |            |                  |         |
-   ffff8d7ffee00000 |  -114.5 TB | ffff8d7ffeffffff |    2 MB | fixmap
+   ffff8d7ffea00000 |  -114.5 TB | ffff8d7ffeffffff |    6 MB | fixmap
    ffff8d7fff000000 |  -114.5 TB | ffff8d7fffffffff |   16 MB | PCI io
    ffff8d8000000000 |  -114.5 TB | ffff8f7fffffffff |    2 TB | vmemmap
    ffff8f8000000000 |  -112.5 TB | ffffaf7fffffffff |   32 TB | vmalloc/ioremap space