Go to file
Albert Ou 922b0375fc riscv: Fix memblock reservation for device tree blob
This fixes an error with how the FDT blob is reserved in memblock.
An incorrect physical address calculation exposed the FDT header to
unintended corruption, which typically manifested with of_fdt_raw_init()
faulting during late boot after fdt_totalsize() returned a wrong value.
Systems with smaller physical memory sizes more frequently trigger this
issue, as the kernel is more likely to allocate from the DMA32 zone
where bbl places the DTB after the kernel image.

Commit 671f9a3e2e ("RISC-V: Setup initial page tables in two stages")
changed the mapping of the DTB to reside in the fixmap area.
Consequently, early_init_fdt_reserve_self() cannot be used anymore in
setup_bootmem() since it relies on __pa() to derive a physical address,
which does not work with dtb_early_va that is no longer a valid kernel
logical address.

The reserved[0x1] region shows the effect of the pointer underflow
resulting from the __pa(initial_boot_params) offset subtraction:

[    0.000000] MEMBLOCK configuration:
[    0.000000]  memory size = 0x000000001fe00000 reserved size = 0x0000000000a2e514
[    0.000000]  memory.cnt  = 0x1
[    0.000000]  memory[0x0]     [0x0000000080200000-0x000000009fffffff], 0x000000001fe00000 bytes flags: 0x0
[    0.000000]  reserved.cnt  = 0x2
[    0.000000]  reserved[0x0]   [0x0000000080200000-0x0000000080c2dfeb], 0x0000000000a2dfec bytes flags: 0x0
[    0.000000]  reserved[0x1]   [0xfffffff080100000-0xfffffff080100527], 0x0000000000000528 bytes flags: 0x0

With the fix applied:

[    0.000000] MEMBLOCK configuration:
[    0.000000]  memory size = 0x000000001fe00000 reserved size = 0x0000000000a2e514
[    0.000000]  memory.cnt  = 0x1
[    0.000000]  memory[0x0]     [0x0000000080200000-0x000000009fffffff], 0x000000001fe00000 bytes flags: 0x0
[    0.000000]  reserved.cnt  = 0x2
[    0.000000]  reserved[0x0]   [0x0000000080200000-0x0000000080c2dfeb], 0x0000000000a2dfec bytes flags: 0x0
[    0.000000]  reserved[0x1]   [0x0000000080e00000-0x0000000080e00527], 0x0000000000000528 bytes flags: 0x0

Fixes: 671f9a3e2e ("RISC-V: Setup initial page tables in two stages")
Signed-off-by: Albert Ou <aou@eecs.berkeley.edu>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
2019-10-01 13:22:39 -07:00
Documentation Documentation/process update for 5.4-rc1 2019-09-29 19:52:52 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
arch riscv: Fix memblock reservation for device tree blob 2019-10-01 13:22:39 -07:00
block block: fix null pointer dereference in blk_mq_rq_timed_out() 2019-09-27 07:01:25 -06:00
certs PKCS#7: Refactor verify_pkcs7_signature() 2019-08-05 18:40:18 -04:00
crypto Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-09-28 08:14:15 -07:00
drivers ARM: SoC fixes 2019-09-30 10:04:28 -07:00
fs for-5.4-rc1-tag 2019-09-30 10:25:24 -07:00
include A few more tracing fixes: 2019-09-30 09:29:53 -07:00
init Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-09-28 08:14:15 -07:00
ipc ipc/sem.c: convert to use built-in RCU list checking 2019-09-25 17:51:41 -07:00
kernel A few more tracing fixes: 2019-09-30 09:29:53 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-09-28 17:47:33 -07:00
mm Merge branch 'hugepage-fallbacks' (hugepatch patches from David Rientjes) 2019-09-28 14:26:47 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-09-28 17:47:33 -07:00
samples rpmsg updates for v5.4 2019-09-22 10:58:15 -07:00
scripts Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity 2019-09-27 19:37:27 -07:00
security Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-09-28 08:14:15 -07:00
sound sound fixes for 5.4-rc1 2019-09-24 16:46:16 -07:00
tools A few more tracing fixes: 2019-09-30 09:29:53 -07:00
usr Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-09-28 17:47:33 -07:00
virt * s390: ioctl hardening, selftests 2019-09-18 09:49:13 -07:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Modules updates for v5.4 2019-09-22 10:34:46 -07:00
.mailmap Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next 2019-09-18 12:34:53 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS CREDITS: Update email address 2019-09-13 17:21:38 +03:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS ARM SCMI fixes for v5.4 2019-09-29 11:20:41 -07:00
Makefile Linux 5.4-rc1 2019-09-30 10:35:40 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.