From: Mark Rutland mark.rutland@arm.com
commit 2e8cff0a0eee87b27f0cf87ad8310eb41b5886ab upstream.
On arm64, "rodata=full" has been suppored (but not documented) since commit:
c55191e96caa9d78 ("arm64: mm: apply r/o permissions of VM areas to its linear alias as well")
As it's necessary to determine the rodata configuration early during boot, arm64 has an early_param() handler for this, whereas init/main.c has a __setup() handler which is run later.
Unfortunately, this split meant that since commit:
f9a40b0890658330 ("init/main.c: return 1 from handled __setup() functions")
... passing "rodata=full" would result in a spurious warning from the __setup() handler (though RO permissions would be configured appropriately).
Further, "rodata=full" has been broken since commit:
0d6ea3ac94ca77c5 ("lib/kstrtox.c: add "false"/"true" support to kstrtobool()")
... which caused strtobool() to parse "full" as false (in addition to many other values not documented for the "rodata=" kernel parameter.
This patch fixes this breakage by:
* Moving the core parameter parser to an __early_param(), such that it is available early.
* Adding an (optional) arch hook which arm64 can use to parse "full".
* Updating the documentation to mention that "full" is valid for arm64.
* Having the core parameter parser handle "on" and "off" explicitly, such that any undocumented values (e.g. typos such as "ful") are reported as errors rather than being silently accepted.
Note that __setup() and early_param() have opposite conventions for their return values, where __setup() uses 1 to indicate a parameter was handled and early_param() uses 0 to indicate a parameter was handled.
Fixes: f9a40b089065 ("init/main.c: return 1 from handled __setup() functions") Fixes: 0d6ea3ac94ca ("lib/kstrtox.c: add "false"/"true" support to kstrtobool()") Signed-off-by: Mark Rutland mark.rutland@arm.com Cc: Andy Shevchenko andy.shevchenko@gmail.com Cc: Ard Biesheuvel ardb@kernel.org Cc: Catalin Marinas catalin.marinas@arm.com Cc: Jagdish Gediya jvgediya@linux.ibm.com Cc: Matthew Wilcox willy@infradead.org Cc: Randy Dunlap rdunlap@infradead.org Cc: Will Deacon will@kernel.org Reviewed-by: Ard Biesheuvel ardb@kernel.org Link: https://lore.kernel.org/r/20220817154022.3974645-1-mark.rutland@arm.com Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- Documentation/admin-guide/kernel-parameters.txt | 2 ++ arch/arm64/include/asm/setup.h | 17 +++++++++++++++++ arch/arm64/mm/mmu.c | 18 ------------------ init/main.c | 18 +++++++++++++++--- 4 files changed, 34 insertions(+), 21 deletions(-)
--- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5260,6 +5260,8 @@ rodata= [KNL] on Mark read-only kernel memory as read-only (default). off Leave read-only kernel memory writable for debugging. + full Mark read-only kernel memory and aliases as read-only + [arm64]
rockchip.usb_uart Enable the uart passthrough on the designated usb port --- a/arch/arm64/include/asm/setup.h +++ b/arch/arm64/include/asm/setup.h @@ -3,6 +3,8 @@ #ifndef __ARM64_ASM_SETUP_H #define __ARM64_ASM_SETUP_H
+#include <linux/string.h> + #include <uapi/asm/setup.h>
void *get_early_fdt_ptr(void); @@ -14,4 +16,19 @@ void early_fdt_map(u64 dt_phys); extern phys_addr_t __fdt_pointer __initdata; extern u64 __cacheline_aligned boot_args[4];
+static inline bool arch_parse_debug_rodata(char *arg) +{ + extern bool rodata_enabled; + extern bool rodata_full; + + if (arg && !strcmp(arg, "full")) { + rodata_enabled = true; + rodata_full = true; + return true; + } + + return false; +} +#define arch_parse_debug_rodata arch_parse_debug_rodata + #endif --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -625,24 +625,6 @@ static void __init map_kernel_segment(pg vm_area_add_early(vma); }
-static int __init parse_rodata(char *arg) -{ - int ret = strtobool(arg, &rodata_enabled); - if (!ret) { - rodata_full = false; - return 0; - } - - /* permit 'full' in addition to boolean options */ - if (strcmp(arg, "full")) - return -EINVAL; - - rodata_enabled = true; - rodata_full = true; - return 0; -} -early_param("rodata", parse_rodata); - #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 static int __init map_entry_trampoline(void) { --- a/init/main.c +++ b/init/main.c @@ -1446,13 +1446,25 @@ static noinline void __init kernel_init_
#if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX) bool rodata_enabled __ro_after_init = true; + +#ifndef arch_parse_debug_rodata +static inline bool arch_parse_debug_rodata(char *str) { return false; } +#endif + static int __init set_debug_rodata(char *str) { - if (strtobool(str, &rodata_enabled)) + if (arch_parse_debug_rodata(str)) + return 0; + + if (str && !strcmp(str, "on")) + rodata_enabled = true; + else if (str && !strcmp(str, "off")) + rodata_enabled = false; + else pr_warn("Invalid option string for rodata: '%s'\n", str); - return 1; + return 0; } -__setup("rodata=", set_debug_rodata); +early_param("rodata", set_debug_rodata); #endif
#ifdef CONFIG_STRICT_KERNEL_RWX