kernel/git/next/linux-next.git/lib/bootconfig.c, branch master

bootconfig: add xbc_prepend_embedded_cmdline() helper

2026-07-02T12:15:45+00:00

Add a helper that prepends the build-time-rendered embedded bootconfig "kernel" subtree (embedded_kernel_cmdline[] from embedded-cmdline.S) to a cmdline buffer with a separating space. Architectures call this from setup_arch() before parse_early_param() so early_param() handlers (mem=, earlycon=, loglevel=, ...) see values supplied via the embedded bootconfig. The in-place prepend (shift the existing string right, then drop the embedded string in front) is factored into a small str_prepend() helper. On overflow the helper logs an error and leaves the cmdline untouched rather than panicking. Booting without the embedded values is better than refusing to boot, and the error tells the user why their embedded keys are missing. The helper records whether it actually prepended, exposed via xbc_embedded_cmdline_applied(). setup_boot_config() uses this to decide whether the runtime "kernel" render would duplicate keys already folded into boot_command_line. Also add bootconfig_cmdline_requested(), a small parse_args() wrapper that reports whether "bootconfig" was passed on the command line and, via an optional out-parameter, where the "--" init arguments begin. setup_arch() and setup_boot_config() share it so the early and late paths agree on the opt-in. It sits under CONFIG_BOOT_CONFIG rather than CONFIG_CMDLINE_FROM_BOOTCONFIG because the runtime parser needs it on every bootconfig build. When CONFIG_CMDLINE_FROM_BOOTCONFIG=n, the public declaration in resolves to a no-op stub so callers compile unchanged. Link: https://lore.kernel.org/all/20260626-bootconfig_using_tools-v7-5-24ab72139c29@debian.org/ Signed-off-by: Breno Leitao Signed-off-by: Masami Hiramatsu (Google)

bootconfig: render descendant keys when xbc_snprint_cmdline() root has a value

2026-07-02T12:15:44+00:00

xbc_node_for_each_key_value() walks to the first leaf under @root, and when @root is itself a leaf it yields @root. That happens not only for an empty "kernel {}" subtree, but also when @root carries both a value and subkeys, e.g. kernel = x kernel.foo = bar Here @root ("kernel") is a leaf because its first child is the value node "x", so the iterator returns @root first. Feeding @root back into xbc_node_compose_key_after(root, root) returns -EINVAL, which the only in-kernel caller papers over with a "len <= 0" check -- but the follow-up tools/bootconfig -C user propagates the error and turns such a bootconfig into a build failure. Worse, short-circuiting the whole call on a leaf @root would silently drop the valid "kernel.foo = bar" descendant that this patch should render. Skip @root inside the loop instead of bailing out: the value-only entry is dropped (it is rendered through the "kernel" cmdline path, not here), while real descendant keys are still emitted. An entirely empty subtree now renders nothing and returns 0 rather than -EINVAL, matching the "nothing to render is not an error" semantics expected by the new build-time caller. Link: https://lore.kernel.org/all/20260626-bootconfig_using_tools-v7-2-24ab72139c29@debian.org/ Signed-off-by: Breno Leitao Signed-off-by: Masami Hiramatsu (Google)

bootconfig: fix NULL-pointer arithmetic in xbc_snprint_cmdline()

2026-06-30T23:08:27+00:00

xbc_snprint_cmdline() is meant to be called twice: first with buf=NULL, size=0 to probe the rendered length, then with a real buffer to fill it (the standard snprintf() two-pass pattern). The probe call makes the function compute "buf + size" (NULL + 0) and, on every iteration, advance "buf += ret" from that NULL base and pass the result back into snprintf(). Pointer arithmetic on a NULL pointer is undefined behavior. It is harmless in the in-kernel callers today, but the follow-up patches run this same code in the userspace tools/bootconfig parser at kernel build time, where host UBSan / FORTIFY_SOURCE abort the build. Track a running written length (size_t) instead of mutating @buf, and only form "buf + len" when @buf is non-NULL. snprintf(NULL, 0, ...) is itself well defined and returns the would-be length, so the two-pass "probe then fill" usage returns identical byte counts. Link: https://lore.kernel.org/all/20260626-bootconfig_using_tools-v7-1-24ab72139c29@debian.org/ Fixes: 51887d03aca1 ("bootconfig: init: Allow admin to use bootconfig for kernel command line") Cc: stable@vger.kernel.org Signed-off-by: Breno Leitao Signed-off-by: Masami Hiramatsu (Google)

bootconfig: move xbc_snprint_cmdline() to lib/bootconfig.c

2026-05-12T00:44:31+00:00

Move xbc_snprint_cmdline() from init/main.c to lib/bootconfig.c so the function (and its xbc_namebuf scratch buffer) becomes part of the shared parser library. tools/bootconfig already compiles lib/bootconfig.c directly, which lets a follow-up patch reuse the same renderer in the userspace tool to convert a bootconfig file into a flat cmdline string at build time. No functional change. Link: https://lore.kernel.org/all/20260508-bootconfig_using_tools-v1-1-1132219aa773@debian.org/ Signed-off-by: Breno Leitao Signed-off-by: Masami Hiramatsu (Google)

Merge tag 'memblock-v7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock

2026-04-18T18:29:14+00:00

Pull memblock updates from Mike Rapoport: - improve debuggability of reserve_mem kernel parameter handling with print outs in case of a failure and debugfs info showing what was actually reserved - Make memblock_free_late() and free_reserved_area() use the same core logic for freeing the memory to buddy and ensure it takes care of updating memblock arrays when ARCH_KEEP_MEMBLOCK is enabled. * tag 'memblock-v7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock: x86/alternative: delay freeing of smp_locks section memblock: warn when freeing reserved memory before memory map is initialized memblock, treewide: make memblock_free() handle late freeing memblock: make free_reserved_area() update memblock if ARCH_KEEP_MEMBLOCK=y memblock: extract page freeing from free_reserved_area() into a helper memblock: make free_reserved_area() more robust mm: move free_reserved_area() to mm/memblock.c powerpc: opal-core: pair alloc_pages_exact() with free_pages_exact() powerpc: fadump: pair alloc_pages_exact() with free_pages_exact() memblock: reserve_mem: fix end caclulation in reserve_mem_release_by_name() memblock: move reserve_bootmem_range() to memblock.c and make it static memblock: Add reserve_mem debugfs info memblock: Print out errors on reserve_mem parser

memblock, treewide: make memblock_free() handle late freeing

2026-04-01T08:20:15+00:00

It shouldn't be responsibility of memblock users to detect if they free memory allocated from memblock late and should use memblock_free_late(). Make memblock_free() and memblock_phys_free() take care of late memory freeing and drop memblock_free_late(). Link: https://patch.msgid.link/20260323074836.3653702-9-rppt@kernel.org Signed-off-by: Mike Rapoport (Microsoft)

lib/bootconfig: change xbc_node_index() return type to uint16_t

2026-03-18T23:45:11+00:00

lib/bootconfig.c:136:21: warning: conversion from 'long int' to 'int' may change value [-Wconversion] lib/bootconfig.c:308:33: warning: conversion from 'int' to 'uint16_t' may change value [-Wconversion] lib/bootconfig.c:467:37: warning: conversion from 'int' to 'uint16_t' may change value [-Wconversion] lib/bootconfig.c:469:40: warning: conversion from 'int' to 'uint16_t' may change value [-Wconversion] lib/bootconfig.c:472:54: warning: conversion from 'int' to 'uint16_t' may change value [-Wconversion] lib/bootconfig.c:476:45: warning: conversion from 'int' to 'uint16_t' may change value [-Wconversion] xbc_node_index() returns the position of a node in the xbc_nodes array, which has at most XBC_NODE_MAX (8192) entries, well within uint16_t range. Every caller stores the result in a uint16_t field (node->parent, node->child, node->next, or the keys[] array in compose_key_after), so the int return type causes narrowing warnings at all six call sites. Change the return type to uint16_t and add an explicit cast on the pointer subtraction to match the storage width and eliminate the warnings. Link: https://lore.kernel.org/all/20260318155919.78168-14-objecting@objecting.org/ Signed-off-by: Josh Law Signed-off-by: Masami Hiramatsu (Google)

lib/bootconfig: use size_t for key length tracking in xbc_verify_tree()

2026-03-18T23:44:58+00:00

lib/bootconfig.c:839:24: warning: conversion from 'size_t' to 'int' may change value [-Wconversion] lib/bootconfig.c:860:32: warning: conversion from 'size_t' to 'int' may change value [-Wconversion] lib/bootconfig.c:860:29: warning: conversion to 'size_t' from 'int' may change the sign of the result [-Wsign-conversion] The key length variables len and wlen accumulate strlen() results but were declared as int, causing truncation and sign-conversion warnings. Change both to size_t to match the strlen() return type and avoid mixed-sign arithmetic. Link: https://lore.kernel.org/all/20260318155919.78168-13-objecting@objecting.org/ Signed-off-by: Josh Law Signed-off-by: Masami Hiramatsu (Google)

lib/bootconfig: use signed type for offset in xbc_init_node()

2026-03-18T23:44:46+00:00

lib/bootconfig.c:415:32: warning: conversion to 'long unsigned int' from 'long int' may change the sign of the result [-Wsign-conversion] Pointer subtraction yields ptrdiff_t (signed), which was stored in unsigned long. The original unsigned type implicitly caught a negative offset (data < xbc_data) because the wrapped value would exceed XBC_DATA_MAX. Make this intent explicit by using a signed long and adding an offset < 0 check to the WARN_ON condition. Link: https://lore.kernel.org/all/20260318155919.78168-12-objecting@objecting.org/ Signed-off-by: Josh Law Signed-off-by: Masami Hiramatsu (Google)

lib/bootconfig: use size_t for strlen result in xbc_node_match_prefix()

2026-03-18T23:44:34+00:00

lib/bootconfig.c:198:19: warning: conversion from 'size_t' to 'int' may change value [-Wconversion] lib/bootconfig.c:200:33: warning: conversion to '__kernel_size_t' from 'int' may change the sign of the result [-Wsign-conversion] strlen() returns size_t but the result was stored in an int. The value is then passed back to strncmp() which expects size_t, causing a second sign-conversion warning on the round-trip. Use size_t throughout to match the API types. Link: https://lore.kernel.org/all/20260318155919.78168-11-objecting@objecting.org/ Signed-off-by: Josh Law Signed-off-by: Masami Hiramatsu (Google)