Add a special module area on top of the vmalloc area, which may be only
used for modules and bpf jit generated code.
This makes sure that inter module branches will always happen without a
trampoline and in addition having all the code within a 2GB frame is
branch prediction unit friendly.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This is more or less the same as the x86 page table dumper which was
merged four years ago: 926e5392 "x86: add code to dump the (kernel)
page tables for visual inspection by kernel developers".
We add a file at /sys/kernel/debug/kernel_page_tables for debugging
purposes so it's quite easy to see the kernel page table layout and
possible odd mappings:
---[ Identity Mapping ]---
0x0000000000000000-0x0000000000100000 1M PTE RW
---[ Kernel Image Start ]---
0x0000000000100000-0x0000000000800000 7M PMD RO
0x0000000000800000-0x00000000008a9000 676K PTE RO
0x00000000008a9000-0x0000000000900000 348K PTE RW
0x0000000000900000-0x0000000001500000 12M PMD RW
---[ Kernel Image End ]---
0x0000000001500000-0x0000000280000000 10219M PMD RW
0x0000000280000000-0x000003d280000000 3904G PUD I
---[ vmemmap Area ]---
0x000003d280000000-0x000003d288c00000 140M PTE RW
0x000003d288c00000-0x000003d300000000 1908M PMD I
0x000003d300000000-0x000003e000000000 52G PUD I
---[ vmalloc Area ]---
0x000003e000000000-0x000003e000009000 36K PTE RW
0x000003e000009000-0x000003e0000ee000 916K PTE I
0x000003e0000ee000-0x000003e000146000 352K PTE RW
0x000003e000146000-0x000003e000200000 744K PTE I
0x000003e000200000-0x000003e080000000 2046M PMD I
0x000003e080000000-0x0000040000000000 126G PUD I
This usually makes only sense for kernel developers. The output
with CONFIG_DEBUG_PAGEALLOC is not very helpful, because of the
huge number of mapped out pages, however I decided for the time
being to not add a !DEBUG_PAGEALLOC dependency.
Maybe it's helpful for somebody even with that option.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Heiko Carstens