[PATCH v3 15/60] arm64: kernel: Don't rely on objcopy to make code under pi/ __init

Ard Biesheuvel
2023-03-07T14:08:28Z

We will add some code under pi/ that contains global variables that
should not end up in __initdata, as they will not be writable via the
initial ID map. So only rely on objcopy for making the libfdt code
__init, and use explicit annotations for the rest.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/arm64/kernel/pi/Makefile | 6 ++++--
arch/arm64/kernel/pi/kaslr_early.c | 16 +++++++++-------
2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/kernel/pi/Makefile b/arch/arm64/kernel/pi/Makefile
index bc32a431fe35e6f4..2bbe866417d453ff 100644
--- a/arch/arm64/kernel/pi/Makefile
+++ b/arch/arm64/kernel/pi/Makefile
@@ -28,11 +28,13 @@ quiet_cmd_piobjcopy = $(quiet_cmd_objcopy)
cmd_piobjcopy = $(cmd_objcopy) && $(obj)/relacheck $(@) $(<)

$(obj)/%.pi.o: OBJCOPYFLAGS := --prefix-symbols=__pi_ \
- --remove-section=.note.gnu.property \
- --prefix-alloc-sections=.init
+ --remove-section=.note.gnu.property
$(obj)/%.pi.o: $(obj)/%.o $(obj)/relacheck FORCE
$(call if_changed,piobjcopy)

+# ensure that all the lib- code ends up as __init code and data
+$(obj)/lib-%.pi.o: OBJCOPYFLAGS += --prefix-alloc-sections=.init
+
$(obj)/lib-%.o: $(srctree)/lib/%.c FORCE
$(call if_changed_rule,cc_o_c)

diff --git a/arch/arm64/kernel/pi/kaslr_early.c b/arch/arm64/kernel/pi/kaslr_early.c
index b9e0bb4bc6a9766f..167081b30a152d0a 100644
--- a/arch/arm64/kernel/pi/kaslr_early.c
+++ b/arch/arm64/kernel/pi/kaslr_early.c
@@ -17,7 +17,7 @@
#include <asm/pgtable.h>

/* taken from lib/string.c */
-static char *__strstr(const char *s1, const char *s2)
+static char *__init __strstr(const char *s1, const char *s2)
{
size_t l1, l2;

@@ -33,7 +33,7 @@ static char *__strstr(const char *s1, const char *s2)
}
return NULL;
}
-static bool cmdline_contains_nokaslr(const u8 *cmdline)
+static bool __init cmdline_contains_nokaslr(const u8 *cmdline)
{
const u8 *str;

@@ -41,7 +41,7 @@ static bool cmdline_contains_nokaslr(const u8 *cmdline)
return str == cmdline || (str > cmdline && *(str - 1) == ' ');
}

-static bool is_kaslr_disabled_cmdline(void *fdt)
+static bool __init is_kaslr_disabled_cmdline(void *fdt)
{
if (!IS_ENABLED(CONFIG_CMDLINE_FORCE)) {
int node;
@@ -67,17 +67,19 @@ static bool is_kaslr_disabled_cmdline(void *fdt)
return cmdline_contains_nokaslr(CONFIG_CMDLINE);
}

-static u64 get_kaslr_seed(void *fdt)
+static u64 __init get_kaslr_seed(void *fdt)
{
+ static char const chosen_str[] __initconst = "chosen";
+ static char const seed_str[] __initconst = "kaslr-seed";
int node, len;
fdt64_t *prop;
u64 ret;

- node = fdt_path_offset(fdt, "/chosen");
+ node = fdt_path_offset(fdt, chosen_str);
if (node < 0)
return 0;

- prop = fdt_getprop_w(fdt, node, "kaslr-seed", &len);
+ prop = fdt_getprop_w(fdt, node, seed_str, &len);
if (!prop || len != sizeof(u64))
return 0;

@@ -86,7 +88,7 @@ static u64 get_kaslr_seed(void *fdt)
return ret;
}

-asmlinkage u64 kaslr_early_init(void *fdt)
+asmlinkage u64 __init kaslr_early_init(void *fdt)
{
u64 seed, range;

--
2.39.2