[PW_SID:1148125] init, arch: make command line size and init arg limit configurable - #2488
[PW_SID:1148125] init, arch: make command line size and init arg limit configurable#2488linux-riscv-bot wants to merge 5 commits into
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…_RWX When CONFIG_STRICT_MODULE_RWX is not set, execmem cannot create temporary writable mappings for read-only executable pages. In this case, the execmem ranges must already have writable permissions. Currently EXECMEM_KPROBES unconditionally uses PAGE_KERNEL_READ_EXEC, which causes kprobe instruction slot writes to trigger page faults on systems where CONFIG_STRICT_MODULE_RWX is not enabled. Fix this by using PAGE_KERNEL_EXEC when CONFIG_STRICT_MODULE_RWX is not available. Signed-off-by: Xiaofeng Yuan <xiaofengmian@163.com> Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> Reviewed-by: Nam Cao <namcao@linutronix.de> Link: https://patch.msgid.link/20260814082742.148403-2-xiaofengmian@163.com Signed-off-by: Paul Walmsley <pjw@kernel.org>
patch_map() always creates a temporary writable mapping via fixmap for kernel text addresses, even when CONFIG_STRICT_KERNEL_RWX is disabled and the kernel text is already mapped with _PAGE_WRITE. This is unnecessary overhead at best, and on minimal configurations it can cause page faults. Skip the fixmap path for kernel text when CONFIG_STRICT_KERNEL_RWX is not enabled, since the text pages are already writable in that case. The module text path is already gated on CONFIG_STRICT_MODULE_RWX and is kept unchanged. Reported-by: Klara Modin <klara@kasm.eu> Closes: https://lore.kernel.org/all/ant_8TaBbov_GS4i@soda.int.kasm.eu/ Reported-by: Lad Prabhakar <prabhakar.csengg@gmail.com> Closes: https://lore.kernel.org/all/CA+V-a8tQK8rih9SGGTyqrEBGpNkx4H0eX2YccCRrgkVAPr+EBg@mail.gmail.com/ Tested-by: Klara Modin <klarasmodin@gmail.com> Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> Link: https://patch.msgid.link/20260814082742.148403-3-xiaofengmian@163.com Signed-off-by: Paul Walmsley <pjw@kernel.org>
Currently, s390 has the ability to configure the maximum kernel command line size via Kconfig (CONFIG_COMMAND_LINE_SIZE). Other architectures define a hardcoded COMMAND_LINE_SIZE macro in their setup.h headers. In some use cases, such as netboot kernels, rootfs configurations, or larger initramfs setups, a larger command line size is required. While for embedded workloads, it can be reduced to save memory. Move CONFIG_COMMAND_LINE_SIZE out of arch/s390/Kconfig and into init/Kconfig under General setup, and update every architecture's setup.h header to define COMMAND_LINE_SIZE as CONFIG_COMMAND_LINE_SIZE. For user-space API (uapi) headers, wrap the definition in an `#ifdef __KERNEL__` guard and retain the historical hardcoded default in the `#else` block. When user-space headers are installed via `make headers_install`, unifdef strips out the kernel section, ensuring the same value as before for user-space applications including `<asm/setup.h>`. For S390, the range is kept the same, but other architectures have varying constraints. S390 requires a minimum of 896 bytes to protect legacy bootloaders from overwriting the .text section. ARM, M68K, and NIOS2 allocate the command line directly on severely constrained decompressor stacks, so their ranges are strictly capped at 2048 bytes to prevent deterministic stack exhaustion and boot panics. PowerPC (PPC) boot wrappers silently truncate arguments past 2048 bytes, so it is also capped at 2048 to prevent silent parameter loss. The SuperH (SUPERH) boot parameter page allocates exactly PAGE_SIZE (typically 4096 bytes), and placing a 4096-byte command line starting at offset 256 would cause strscpy() to read out of bounds; it is capped at 3840 bytes. Alpha physically limits its boot parameter block to 256 bytes, so its limit is strictly locked to 256. All other architectures are capped at 4096 bytes to prevent unreasonable allocations. Signed-off-by: Maciej Żenczykowski <maze@google.com> Signed-off-by: Wilson Felipe Pereira <wfelipe@google.com> Signed-off-by: Linux RISC-V bot <linux.riscv.bot@gmail.com>
INIT_ENV_ARG_LIMIT is defined without a prompt string (`int`), making it
a hidden Kconfig symbol that defaults to 32 (or 128 for UML) and cannot
be configured in `make menuconfig`.
Now that CONFIG_COMMAND_LINE_SIZE is configurable across all architectures,
users who select larger kernel command lines (e.g., 4096 bytes) may pass
more than 32 command-line arguments or environment variables (`foo=bar`) to
`/sbin/init`. If INIT_ENV_ARG_LIMIT remains hardcoded at 32, any argument
after the 32nd sets the panic_later flag and causes a hard kernel panic
on boot.
Add a prompt string ("Maximum number of kernel command line arguments") and
a `range 32 4096` to `config INIT_ENV_ARG_LIMIT` so that users can
configure their init argument and environment variable limit when needed,
while preserving the existing default of 32 for standard builds.
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: Wilson Felipe Pereira <wfelipe@google.com>
Signed-off-by: Linux RISC-V bot <linux.riscv.bot@gmail.com>
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Patch 1: "[v2,1/2] init, arch: make CONFIG_COMMAND_LINE_SIZE globally configurable" |
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Patch 1: "[v2,1/2] init, arch: make CONFIG_COMMAND_LINE_SIZE globally configurable" |
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Patch 1: "[v2,1/2] init, arch: make CONFIG_COMMAND_LINE_SIZE globally configurable" |
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Patch 1: "[v2,1/2] init, arch: make CONFIG_COMMAND_LINE_SIZE globally configurable" |
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Patch 1: "[v2,1/2] init, arch: make CONFIG_COMMAND_LINE_SIZE globally configurable" |
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Patch 1: "[v2,1/2] init, arch: make CONFIG_COMMAND_LINE_SIZE globally configurable" |
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Patch 1: "[v2,1/2] init, arch: make CONFIG_COMMAND_LINE_SIZE globally configurable" |
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Patch 1: "[v2,1/2] init, arch: make CONFIG_COMMAND_LINE_SIZE globally configurable" |
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Patch 1: "[v2,1/2] init, arch: make CONFIG_COMMAND_LINE_SIZE globally configurable" |
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Patch 1: "[v2,1/2] init, arch: make CONFIG_COMMAND_LINE_SIZE globally configurable" |
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Patch 1: "[v2,1/2] init, arch: make CONFIG_COMMAND_LINE_SIZE globally configurable" |
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Patch 1: "[v2,1/2] init, arch: make CONFIG_COMMAND_LINE_SIZE globally configurable" |
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Patch 2: "[v2,2/2] init/Kconfig: make config INIT_ENV_ARG_LIMIT user-configurable" |
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Patch 2: "[v2,2/2] init/Kconfig: make config INIT_ENV_ARG_LIMIT user-configurable" |
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Patch 2: "[v2,2/2] init/Kconfig: make config INIT_ENV_ARG_LIMIT user-configurable" |
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Patch 2: "[v2,2/2] init/Kconfig: make config INIT_ENV_ARG_LIMIT user-configurable" |
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Patch 2: "[v2,2/2] init/Kconfig: make config INIT_ENV_ARG_LIMIT user-configurable" |
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Patch 2: "[v2,2/2] init/Kconfig: make config INIT_ENV_ARG_LIMIT user-configurable" |
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Patch 2: "[v2,2/2] init/Kconfig: make config INIT_ENV_ARG_LIMIT user-configurable" |
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Patch 2: "[v2,2/2] init/Kconfig: make config INIT_ENV_ARG_LIMIT user-configurable" |
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Patch 2: "[v2,2/2] init/Kconfig: make config INIT_ENV_ARG_LIMIT user-configurable" |
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Patch 2: "[v2,2/2] init/Kconfig: make config INIT_ENV_ARG_LIMIT user-configurable" |
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Patch 2: "[v2,2/2] init/Kconfig: make config INIT_ENV_ARG_LIMIT user-configurable" |
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Patch 2: "[v2,2/2] init/Kconfig: make config INIT_ENV_ARG_LIMIT user-configurable" |
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3 participants
PR for series 1148125 applied to workflow__riscv__fixes
Name: init, arch: make command line size and init arg limit configurable
URL: https://patchwork.kernel.org/project/linux-riscv/list/?series=1148125
Version: 2