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: f9a40b0890658330 ("init/main.c: return 1 from handled __setup() functions")
Fixes: 0d6ea3ac94ca77c5 ("lib/kstrtox.c: add "false"/"true" support to kstrtobool()")
Signed-off-by: Mark Rutland <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Jagdish Gediya <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Will Deacon <[email protected]>
---
.../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(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index d7f30902fda02..426fa892d311a 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5331,6 +5331,8 @@
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
diff --git a/arch/arm64/include/asm/setup.h b/arch/arm64/include/asm/setup.h
index 6437df6617009..f4af547ef54ca 100644
--- 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
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index db7c4e6ae57bb..e7ad44585f40a 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -642,24 +642,6 @@ static void __init map_kernel_segment(pgd_t *pgdp, void *va_start, void *va_end,
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)
{
diff --git a/init/main.c b/init/main.c
index 91642a4e69be6..1fe7942f5d4a8 100644
--- a/init/main.c
+++ b/init/main.c
@@ -1446,13 +1446,25 @@ static noinline void __init kernel_init_freeable(void);
#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
--
2.30.2
On Wed, 17 Aug 2022 at 17:40, Mark Rutland <[email protected]> wrote:
>
> 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: f9a40b0890658330 ("init/main.c: return 1 from handled __setup() functions")
> Fixes: 0d6ea3ac94ca77c5 ("lib/kstrtox.c: add "false"/"true" support to kstrtobool()")
> Signed-off-by: Mark Rutland <[email protected]>
> Cc: Andy Shevchenko <[email protected]>
> Cc: Ard Biesheuvel <[email protected]>
> Cc: Catalin Marinas <[email protected]>
> Cc: Jagdish Gediya <[email protected]>
> Cc: Matthew Wilcox <[email protected]>
> Cc: Randy Dunlap <[email protected]>
> Cc: Will Deacon <[email protected]>
Yuck, thanks for cleaning that up.
Reviewed-by: Ard Biesheuvel <[email protected]>
> ---
> .../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(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index d7f30902fda02..426fa892d311a 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -5331,6 +5331,8 @@
> 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
> diff --git a/arch/arm64/include/asm/setup.h b/arch/arm64/include/asm/setup.h
> index 6437df6617009..f4af547ef54ca 100644
> --- 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
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index db7c4e6ae57bb..e7ad44585f40a 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -642,24 +642,6 @@ static void __init map_kernel_segment(pgd_t *pgdp, void *va_start, void *va_end,
> 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)
> {
> diff --git a/init/main.c b/init/main.c
> index 91642a4e69be6..1fe7942f5d4a8 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -1446,13 +1446,25 @@ static noinline void __init kernel_init_freeable(void);
>
> #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
> --
> 2.30.2
>
On Wed, 17 Aug 2022 16:40:22 +0100, Mark Rutland wrote:
> 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.
>
> [...]
Applied to arm64 (for-next/fixes), thanks!
[1/1] arm64: fix rodata=full
https://git.kernel.org/arm64/c/2e8cff0a0eee
Cheers,
--
Will
https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev