* [PATCH v6 0/1] riscv: Allow to downgrade paging mode from the command line
@ 2023-02-23 8:24 Alexandre Ghiti
2023-02-23 8:24 ` [PATCH v6 1/1] " Alexandre Ghiti
0 siblings, 1 reply; 4+ messages in thread
From: Alexandre Ghiti @ 2023-02-23 8:24 UTC (permalink / raw)
To: Jonathan Corbet, Paul Walmsley, Palmer Dabbelt, Albert Ou,
Conor Dooley, Ard Biesheuvel, Björn Töpel, linux-doc,
linux-kernel, linux-riscv
Cc: Alexandre Ghiti
This new version gets rid of the limitation that prevented KASAN kernels
to use the newly introduced parameters.
While looking into KASLR, I fell onto commit aacd149b6238 ("arm64: head:
avoid relocating the kernel twice for KASLR"): it allows to use the fdt
functions very early in the boot process with KASAN enabled by simply
compiling a new version of those functions without instrumentation.
I had to change the handling of the command line parsing to make the
code self-contained in kernel/pi/cmd_early.c to avoid calling too many
__pi prefixed functions from outside this file.
I'll use this approach like arm64 to handle the extraction of the random
seedi from the device tree for KASLR.
base-commit-tag: riscv-for-linus-6.2-rc8
v6:
- Fix llvm warning by forward declaring set_satp_mode_from_cmdline
v5:
- Handle null command line, Thanks Björn!
- Add RB/TB from Björn
v4:
- Introduce pi/ for KASAN to work
v3:
- Massage commit log to make no4lvl clearer, as asked by Conor
- Add a note to kernel-parameters.txt regarding the impossibility to use
those parameters when KASAN is enabled, as suggested by Conor
- Add RB from Björn
v2:
- Honor CMDLINE_EXTEND and CMDLINE_FORCE as noticed by Björn
Alexandre Ghiti (1):
riscv: Allow to downgrade paging mode from the command line
.../admin-guide/kernel-parameters.txt | 5 +-
arch/riscv/kernel/Makefile | 2 +
arch/riscv/kernel/pi/Makefile | 34 ++++++++++
arch/riscv/kernel/pi/cmdline_early.c | 62 +++++++++++++++++++
arch/riscv/lib/memcpy.S | 2 +
arch/riscv/lib/memmove.S | 2 +
arch/riscv/mm/init.c | 36 +++++++++--
7 files changed, 136 insertions(+), 7 deletions(-)
create mode 100644 arch/riscv/kernel/pi/Makefile
create mode 100644 arch/riscv/kernel/pi/cmdline_early.c
--
2.37.2
^ permalink raw reply [flat|nested] 4+ messages in thread* [PATCH v6 1/1] riscv: Allow to downgrade paging mode from the command line 2023-02-23 8:24 [PATCH v6 0/1] riscv: Allow to downgrade paging mode from the command line Alexandre Ghiti @ 2023-02-23 8:24 ` Alexandre Ghiti 2023-02-23 12:09 ` kernel test robot 2023-02-23 20:03 ` kernel test robot 0 siblings, 2 replies; 4+ messages in thread From: Alexandre Ghiti @ 2023-02-23 8:24 UTC (permalink / raw) To: Jonathan Corbet, Paul Walmsley, Palmer Dabbelt, Albert Ou, Conor Dooley, Ard Biesheuvel, Björn Töpel, linux-doc, linux-kernel, linux-riscv Cc: Alexandre Ghiti, Björn Töpel Add 2 early command line parameters that allow to downgrade satp mode (using the same naming as x86): - "no5lvl": use a 4-level page table (down from sv57 to sv48) - "no4lvl": use a 3-level page table (down from sv57/sv48 to sv39) Note that going through the device tree to get the kernel command line works with ACPI too since the efi stub creates a device tree anyway with the command line. In KASAN kernels, we can't use the libfdt that early in the boot process since we are not ready to execute instrumented functions. So instead of using the "generic" libfdt, we compile our own versions of those functions that are not instrumented and that are prefixed so that they do not conflict with the generic ones. We also need the non-instrumented versions of the string functions and the prefixed versions of memcpy/memmove. This is largely inspired by commit aacd149b6238 ("arm64: head: avoid relocating the kernel twice for KASLR") from which I removed compilation flags that were not relevant to RISC-V at the moment (LTO, SCS, pie). Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com> Tested-by: Björn Töpel <bjorn@rivosinc.com> Reviewed-by: Björn Töpel <bjorn@rivosinc.com> --- .../admin-guide/kernel-parameters.txt | 5 +- arch/riscv/kernel/Makefile | 2 + arch/riscv/kernel/pi/Makefile | 34 ++++++++++ arch/riscv/kernel/pi/cmdline_early.c | 62 +++++++++++++++++++ arch/riscv/lib/memcpy.S | 2 + arch/riscv/lib/memmove.S | 2 + arch/riscv/mm/init.c | 36 +++++++++-- 7 files changed, 136 insertions(+), 7 deletions(-) create mode 100644 arch/riscv/kernel/pi/Makefile create mode 100644 arch/riscv/kernel/pi/cmdline_early.c diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 6cfa6e3996cf..1d8fc66d2b0d 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3578,7 +3578,10 @@ emulation library even if a 387 maths coprocessor is present. - no5lvl [X86-64] Disable 5-level paging mode. Forces + no4lvl [RISCV] Disable 4-level and 5-level paging modes. Forces + kernel to use 3-level paging instead. + + no5lvl [X86-64,RISCV] Disable 5-level paging mode. Forces kernel to use 4-level paging instead. nofsgsbase [X86] Disables FSGSBASE instructions. diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index 4cf303a779ab..6756209f1ac6 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -89,3 +89,5 @@ obj-$(CONFIG_EFI) += efi.o obj-$(CONFIG_COMPAT) += compat_syscall_table.o obj-$(CONFIG_COMPAT) += compat_signal.o obj-$(CONFIG_COMPAT) += compat_vdso/ + +obj-y += pi/ diff --git a/arch/riscv/kernel/pi/Makefile b/arch/riscv/kernel/pi/Makefile new file mode 100644 index 000000000000..554e936ef0b6 --- /dev/null +++ b/arch/riscv/kernel/pi/Makefile @@ -0,0 +1,34 @@ +# SPDX-License-Identifier: GPL-2.0 +# This file was copied from arm64/kernel/pi/Makefile. + +KBUILD_CFLAGS := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ + -Os -DDISABLE_BRANCH_PROFILING $(DISABLE_STACKLEAK_PLUGIN) \ + $(call cc-option,-mbranch-protection=none) \ + -I$(srctree)/scripts/dtc/libfdt -fno-stack-protector \ + -D__DISABLE_EXPORTS -ffreestanding \ + -fno-asynchronous-unwind-tables -fno-unwind-tables \ + $(call cc-option,-fno-addrsig) + +GCOV_PROFILE := n +KASAN_SANITIZE := n +KCSAN_SANITIZE := n +UBSAN_SANITIZE := n +KCOV_INSTRUMENT := n + +$(obj)/%.pi.o: OBJCOPYFLAGS := --prefix-symbols=__pi_ \ + --remove-section=.note.gnu.property \ + --prefix-alloc-sections=.init +$(obj)/%.pi.o: $(obj)/%.o FORCE + $(call if_changed,objcopy) + +$(obj)/lib-%.o: $(srctree)/lib/%.c FORCE + $(call if_changed_rule,cc_o_c) + +$(obj)/string.o: $(srctree)/lib/string.c FORCE + $(call if_changed_rule,cc_o_c) + +$(obj)/ctype.o: $(srctree)/lib/ctype.c FORCE + $(call if_changed_rule,cc_o_c) + +obj-y := cmdline_early.pi.o string.pi.o ctype.pi.o lib-fdt.pi.o lib-fdt_ro.pi.o +extra-y := $(patsubst %.pi.o,%.o,$(obj-y)) diff --git a/arch/riscv/kernel/pi/cmdline_early.c b/arch/riscv/kernel/pi/cmdline_early.c new file mode 100644 index 000000000000..bb384d310515 --- /dev/null +++ b/arch/riscv/kernel/pi/cmdline_early.c @@ -0,0 +1,62 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include <linux/types.h> +#include <linux/init.h> +#include <linux/libfdt.h> +#include <linux/string.h> +#include <asm/pgtable.h> +#include <asm/setup.h> + +static char early_cmdline[COMMAND_LINE_SIZE] __initdata; + +/* + * Declare the functions that are exported (but prefixed) here so that LLVM + * does not complain it lacks the 'static' keyword (which, if added, makes + * LLVM complain because the function is actually unused in this file). + */ +u64 __init set_satp_mode_from_cmdline(uintptr_t dtb_pa); + +static char * __init get_early_cmdline(uintptr_t dtb_pa) +{ + const char *fdt_cmdline = NULL; + unsigned int fdt_cmdline_size = 0; + int chosen_node; + + if (!IS_ENABLED(CONFIG_CMDLINE_FORCE)) { + chosen_node = fdt_path_offset((void *)dtb_pa, "/chosen"); + if (chosen_node >= 0) { + fdt_cmdline = fdt_getprop((void *)dtb_pa, chosen_node, + "bootargs", NULL); + if (fdt_cmdline) { + fdt_cmdline_size = strlen(fdt_cmdline); + strscpy(early_cmdline, fdt_cmdline, + COMMAND_LINE_SIZE); + } + } + } + + if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) || + IS_ENABLED(CONFIG_CMDLINE_FORCE) || + fdt_cmdline_size == 0 /* CONFIG_CMDLINE_FALLBACK */) { + strncat(early_cmdline, CONFIG_CMDLINE, + COMMAND_LINE_SIZE - fdt_cmdline_size); + } + + return early_cmdline; +} + +static u64 __init match_noXlvl(char *cmdline) +{ + if (strstr(cmdline, "no4lvl")) + return SATP_MODE_48; + else if (strstr(cmdline, "no5lvl")) + return SATP_MODE_57; + + return 0; +} + +u64 __init set_satp_mode_from_cmdline(uintptr_t dtb_pa) +{ + char *cmdline = get_early_cmdline(dtb_pa); + + return match_noXlvl(cmdline); +} diff --git a/arch/riscv/lib/memcpy.S b/arch/riscv/lib/memcpy.S index 51ab716253fa..1a40d01a9543 100644 --- a/arch/riscv/lib/memcpy.S +++ b/arch/riscv/lib/memcpy.S @@ -106,3 +106,5 @@ WEAK(memcpy) 6: ret END(__memcpy) +SYM_FUNC_ALIAS(__pi_memcpy, __memcpy) +SYM_FUNC_ALIAS(__pi___memcpy, __memcpy) diff --git a/arch/riscv/lib/memmove.S b/arch/riscv/lib/memmove.S index e0609e1f0864..838ff2022fe3 100644 --- a/arch/riscv/lib/memmove.S +++ b/arch/riscv/lib/memmove.S @@ -314,3 +314,5 @@ return_from_memmove: SYM_FUNC_END(memmove) SYM_FUNC_END(__memmove) +SYM_FUNC_ALIAS(__pi_memmove, __memmove) +SYM_FUNC_ALIAS(__pi___memmove, __memmove) diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index 478d6763a01a..70c7fc566f63 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -732,6 +732,8 @@ static __init pgprot_t pgprot_from_va(uintptr_t va) #endif /* CONFIG_STRICT_KERNEL_RWX */ #if defined(CONFIG_64BIT) && !defined(CONFIG_XIP_KERNEL) +u64 __pi_set_satp_mode_from_cmdline(uintptr_t dtb_pa); + static void __init disable_pgtable_l5(void) { pgtable_l5_enabled = false; @@ -746,17 +748,39 @@ static void __init disable_pgtable_l4(void) satp_mode = SATP_MODE_39; } +static int __init print_no4lvl(char *p) +{ + pr_info("Disabled 4-level and 5-level paging"); + return 0; +} +early_param("no4lvl", print_no4lvl); + +static int __init print_no5lvl(char *p) +{ + pr_info("Disabled 5-level paging"); + return 0; +} +early_param("no5lvl", print_no5lvl); + /* * There is a simple way to determine if 4-level is supported by the * underlying hardware: establish 1:1 mapping in 4-level page table mode * then read SATP to see if the configuration was taken into account * meaning sv48 is supported. */ -static __init void set_satp_mode(void) +static __init void set_satp_mode(uintptr_t dtb_pa) { u64 identity_satp, hw_satp; uintptr_t set_satp_mode_pmd = ((unsigned long)set_satp_mode) & PMD_MASK; - bool check_l4 = false; + u64 satp_mode_cmdline = __pi_set_satp_mode_from_cmdline(dtb_pa); + + if (satp_mode_cmdline == SATP_MODE_57) { + disable_pgtable_l5(); + } else if (satp_mode_cmdline == SATP_MODE_48) { + disable_pgtable_l5(); + disable_pgtable_l4(); + return; + } create_p4d_mapping(early_p4d, set_satp_mode_pmd, (uintptr_t)early_pud, @@ -775,7 +799,8 @@ static __init void set_satp_mode(void) retry: create_pgd_mapping(early_pg_dir, set_satp_mode_pmd, - check_l4 ? (uintptr_t)early_pud : (uintptr_t)early_p4d, + pgtable_l5_enabled ? + (uintptr_t)early_p4d : (uintptr_t)early_pud, PGDIR_SIZE, PAGE_TABLE); identity_satp = PFN_DOWN((uintptr_t)&early_pg_dir) | satp_mode; @@ -786,9 +811,8 @@ static __init void set_satp_mode(void) local_flush_tlb_all(); if (hw_satp != identity_satp) { - if (!check_l4) { + if (pgtable_l5_enabled) { disable_pgtable_l5(); - check_l4 = true; memset(early_pg_dir, 0, PAGE_SIZE); goto retry; } @@ -979,7 +1003,7 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa) #endif #if defined(CONFIG_64BIT) && !defined(CONFIG_XIP_KERNEL) - set_satp_mode(); + set_satp_mode(dtb_pa); #endif kernel_map.va_pa_offset = PAGE_OFFSET - kernel_map.phys_addr; -- 2.37.2 ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v6 1/1] riscv: Allow to downgrade paging mode from the command line 2023-02-23 8:24 ` [PATCH v6 1/1] " Alexandre Ghiti @ 2023-02-23 12:09 ` kernel test robot 2023-02-23 20:03 ` kernel test robot 1 sibling, 0 replies; 4+ messages in thread From: kernel test robot @ 2023-02-23 12:09 UTC (permalink / raw) To: Alexandre Ghiti, Jonathan Corbet, Paul Walmsley, Palmer Dabbelt, Albert Ou, Conor Dooley, Ard Biesheuvel, Björn Töpel, linux-doc, linux-kernel, linux-riscv Cc: llvm, oe-kbuild-all, Alexandre Ghiti Hi Alexandre, Thank you for the patch! Yet something to improve: [auto build test ERROR on linus/master] [also build test ERROR on v6.2] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch#_base_tree_information] url: https://github.com/intel-lab-lkp/linux/commits/Alexandre-Ghiti/riscv-Allow-to-downgrade-paging-mode-from-the-command-line/20230223-162702 patch link: https://lore.kernel.org/r/20230223082434.1280957-2-alexghiti%40rivosinc.com patch subject: [PATCH v6 1/1] riscv: Allow to downgrade paging mode from the command line config: riscv-buildonly-randconfig-r002-20230222 (https://download.01.org/0day-ci/archive/20230223/202302231942.6C2mSFYv-lkp@intel.com/config) compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project db89896bbbd2251fff457699635acbbedeead27f) reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # install riscv cross compiling tool for clang build # apt-get install binutils-riscv-linux-gnu # https://github.com/intel-lab-lkp/linux/commit/7e18f795579f897e63812ca9dcb5b48ef2b7b4d2 git remote add linux-review https://github.com/intel-lab-lkp/linux git fetch --no-tags linux-review Alexandre-Ghiti/riscv-Allow-to-downgrade-paging-mode-from-the-command-line/20230223-162702 git checkout 7e18f795579f897e63812ca9dcb5b48ef2b7b4d2 # save the config file mkdir build_dir && cp config build_dir/.config COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=riscv olddefconfig COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash arch/riscv/kernel/pi/ If you fix the issue, kindly add following tag where applicable | Reported-by: kernel test robot <lkp@intel.com> | Link: https://lore.kernel.org/oe-kbuild-all/202302231942.6C2mSFYv-lkp@intel.com/ All errors (new ones prefixed by >>): >> arch/riscv/kernel/pi/cmdline_early.c:50:10: error: use of undeclared identifier 'SATP_MODE_48' return SATP_MODE_48; ^ >> arch/riscv/kernel/pi/cmdline_early.c:52:10: error: use of undeclared identifier 'SATP_MODE_57' return SATP_MODE_57; ^ 2 errors generated. vim +/SATP_MODE_48 +50 arch/riscv/kernel/pi/cmdline_early.c 46 47 static u64 __init match_noXlvl(char *cmdline) 48 { 49 if (strstr(cmdline, "no4lvl")) > 50 return SATP_MODE_48; 51 else if (strstr(cmdline, "no5lvl")) > 52 return SATP_MODE_57; 53 54 return 0; 55 } 56 -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v6 1/1] riscv: Allow to downgrade paging mode from the command line 2023-02-23 8:24 ` [PATCH v6 1/1] " Alexandre Ghiti 2023-02-23 12:09 ` kernel test robot @ 2023-02-23 20:03 ` kernel test robot 1 sibling, 0 replies; 4+ messages in thread From: kernel test robot @ 2023-02-23 20:03 UTC (permalink / raw) To: Alexandre Ghiti, Jonathan Corbet, Paul Walmsley, Palmer Dabbelt, Albert Ou, Conor Dooley, Ard Biesheuvel, Björn Töpel, linux-doc, linux-kernel, linux-riscv Cc: oe-kbuild-all, Alexandre Ghiti Hi Alexandre, Thank you for the patch! Yet something to improve: [auto build test ERROR on linus/master] [also build test ERROR on v6.2 next-20230223] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch#_base_tree_information] url: https://github.com/intel-lab-lkp/linux/commits/Alexandre-Ghiti/riscv-Allow-to-downgrade-paging-mode-from-the-command-line/20230223-162702 patch link: https://lore.kernel.org/r/20230223082434.1280957-2-alexghiti%40rivosinc.com patch subject: [PATCH v6 1/1] riscv: Allow to downgrade paging mode from the command line config: riscv-rv32_defconfig (https://download.01.org/0day-ci/archive/20230224/202302240308.1CC475U8-lkp@intel.com/config) compiler: riscv32-linux-gcc (GCC) 12.1.0 reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # https://github.com/intel-lab-lkp/linux/commit/7e18f795579f897e63812ca9dcb5b48ef2b7b4d2 git remote add linux-review https://github.com/intel-lab-lkp/linux git fetch --no-tags linux-review Alexandre-Ghiti/riscv-Allow-to-downgrade-paging-mode-from-the-command-line/20230223-162702 git checkout 7e18f795579f897e63812ca9dcb5b48ef2b7b4d2 # save the config file mkdir build_dir && cp config build_dir/.config COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=riscv olddefconfig COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash If you fix the issue, kindly add following tag where applicable | Reported-by: kernel test robot <lkp@intel.com> | Link: https://lore.kernel.org/oe-kbuild-all/202302240308.1CC475U8-lkp@intel.com/ All errors (new ones prefixed by >>): arch/riscv/kernel/pi/cmdline_early.c: In function 'match_noXlvl': >> arch/riscv/kernel/pi/cmdline_early.c:50:24: error: 'SATP_MODE_48' undeclared (first use in this function); did you mean 'SATP_MODE_32'? 50 | return SATP_MODE_48; | ^~~~~~~~~~~~ | SATP_MODE_32 arch/riscv/kernel/pi/cmdline_early.c:50:24: note: each undeclared identifier is reported only once for each function it appears in >> arch/riscv/kernel/pi/cmdline_early.c:52:24: error: 'SATP_MODE_57' undeclared (first use in this function); did you mean 'SATP_MODE_32'? 52 | return SATP_MODE_57; | ^~~~~~~~~~~~ | SATP_MODE_32 vim +50 arch/riscv/kernel/pi/cmdline_early.c 46 47 static u64 __init match_noXlvl(char *cmdline) 48 { 49 if (strstr(cmdline, "no4lvl")) > 50 return SATP_MODE_48; 51 else if (strstr(cmdline, "no5lvl")) > 52 return SATP_MODE_57; 53 54 return 0; 55 } 56 -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2023-02-23 20:04 UTC | newest] Thread overview: 4+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2023-02-23 8:24 [PATCH v6 0/1] riscv: Allow to downgrade paging mode from the command line Alexandre Ghiti 2023-02-23 8:24 ` [PATCH v6 1/1] " Alexandre Ghiti 2023-02-23 12:09 ` kernel test robot 2023-02-23 20:03 ` kernel test robot
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