Hi all, Sorry for disturbance. No reply to this version for more than one week, any comments? Thanks, Chao Fan On Mon, Oct 22, 2018 at 05:37:13PM +0800, Chao Fan wrote: >***Background: >People reported that kaslr may randomly chooses some positions >which are located in movable memory regions. This will break memory >hotplug feature and make the movable memory chosen by KASLR can't be >removed. > >***Solutions: >There should be a method to limit kaslr to choosing immovable memory >regions, so there are 2 solutions: >1) Add a kernel parameter to specify the memory regions. >2) Get the information of memory hot-remove, then kaslr will know the > right regions. >In method 2, information about memory hot-remove is in ACPI >tables, which will be parsed after start_kernel(), kaslr can't get >the information. >In method 1, users should know the regions address and specify in >kernel parameter. > >In the earliest time, I tried to dig ACPI tabls to solve this problem. >But I didn't splite the code in 'compressed/' and ACPI code, so the patch >is hard to follow so refused by community. >Somebody suggest to add a kernel parameter to specify the >immovable memory so that limit kaslr in these regions. Then I make >a new patchset. After several versions, Ingo gave a suggestion: >https://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg1634024.html >Follow Ingo's suggestion, imitate the ACPI code to parse the acpi >tables, so that the kaslr can get necessary memory information in >ACPI tables. >I think ACPI code is an independent part, so imitate the codes >and functions to 'compressed/' directory, so that kaslr won't >influence the initialization of ACPI. > >PATCH 1/7 Introduce cmdline_find_option_arg() to detect if option=arg > in cmdline >PATCH 2/7 Copy kstrtoull() to compressed period, used to convert memory > address from string to unsigned long long. >PATCH 3/7 Add efi_get_rsdp_addr() to dig out RSDP from EFI table when > booting from EFI. >PATCH 4/7 Add bios_get_rsdp_addr() to search RSDP in memory when EFI > table not found. >PATCH 5/7 Add get_acpi_rsdp() to parse RSDP in cmdline from kexec >PATCH 6/7 Dig out SRAT table from RSDP and walk SRAT table to store > the immovable memory regions. >PATCH 7/7 Calculate the intersection between memory regions from e820/efi > memory table and immovable memory regions. Limit KASLR choose > these regions for randomization. > >v1->v2: > - Simplify some code. >Follow Baoquan He's suggestion: > - Reuse the head file of acpi code. > >v2->v3: > - Test in more conditions, so remove the 'RFC' tag. > - Change some comments. > >v3->v4: >Follow Thomas Gleixner's suggetsion: > - Put the whole efi related function into #define CONFIG_EFI and return > false in the other stub. > >v4->v5: >Follow Dou Liyang's suggestion: > - Add more comments about some functions based on kernel code. > - Change some typo in comments. > - Clean useless variable. > - Add check for the boundary of array. > - Add check for 'movable_node' parameter > >v5->v6: >Follow Baoquan He's suggestion: > - Change some log. > - Add the check for acpi_rsdp > - Change some code logical to make code clear > >v6->v7: >Follow Rafael's suggestion: > - Add more comments and patch log. >Follow test robot's suggestion: > - Add "static" tag for function > >v7-v8: >Follow Kees Cook's suggestion: > - Use mem_overlaps() to check memory region. > - Use #ifdef in the definition of function. > >v8-v9: >Follow Boris' suggetion: > - Change code style. > - Splite PATCH 1/3 to more path. > - Introduce some new function > - Use existing function to rework some code >Follow Masayoshi's suggetion: > - Make code more readable > >v9->v10: >Follow Baoquan's suggestion: > - Change some log > - Merge last two patch together. > >Any comments will be welcome. > >Chao Fan (7): > x86/boot: Introduce cmdline_find_option_arg()to detect if option=arg > in cmdline > x86/boot: Copy kstrtoull() to compressed period > x86/boot: Add efi_get_rsdp_addr() to dig out RSDP from EFI table > x86/boot: Add bios_get_rsdp_addr() to search RSDP in memory > x86/boot: Add get_acpi_rsdp() to parse RSDP in cmdlien from kexec > x86/boot: Dig out SRAT table from RSDP and find immovable memory > x86/boot/KASLR: Limit kaslr to choosing the immovable memory > > arch/x86/boot/compressed/Makefile | 4 + > arch/x86/boot/compressed/acpitb.c | 352 +++++++++++++++++++++++++++++ > arch/x86/boot/compressed/cmdline.c | 15 ++ > arch/x86/boot/compressed/kaslr.c | 81 +++++-- > arch/x86/boot/compressed/misc.c | 88 ++++++++ > arch/x86/boot/compressed/misc.h | 20 ++ > 6 files changed, 545 insertions(+), 15 deletions(-) > create mode 100644 arch/x86/boot/compressed/acpitb.c > >-- >2.17.2 >
