[PATCH v3 34/60] arm64: head: Move early kernel mapping routines into C code

Ard Biesheuvel
2023-03-07T14:10:34Z

The asm version of the kernel mapping code works fine for creating a
coarse grained identity map, but for mapping the kernel down to its
exact boundaries with the right attributes, it is not suitable. This is
why we create a preliminary RWX kernel mapping first, and then rebuild
it from scratch later on.

So let's reimplement this in C, in a way that will make it unnecessary
to create the kernel page tables yet another time in paging_init().

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/arm64/include/asm/mmu.h | 1 -
arch/arm64/include/asm/scs.h | 32 +---
arch/arm64/kernel/cpufeature.c | 2 +-
arch/arm64/kernel/head.S | 52 +-----
arch/arm64/kernel/image-vars.h | 16 ++
arch/arm64/kernel/pi/Makefile | 1 +
arch/arm64/kernel/pi/idreg-override.c | 22 ++-
arch/arm64/kernel/pi/kaslr_early.c | 12 +-
arch/arm64/kernel/pi/map_kernel.c | 171 ++++++++++++++++++++
arch/arm64/kernel/pi/map_range.c | 87 ++++++++++
arch/arm64/kernel/pi/patch-scs.c | 16 +-
arch/arm64/kernel/pi/pi.h | 12 ++
arch/arm64/kernel/pi/relocate.c | 2 +
arch/arm64/kernel/setup.c | 7 -
arch/arm64/kernel/vmlinux.lds.S | 4 +-
arch/arm64/mm/proc.S | 1 +
16 files changed, 317 insertions(+), 121 deletions(-)

diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
index 9b9a206e4e9c9d4e..e74dfae8e48214c3 100644
--- a/arch/arm64/include/asm/mmu.h
+++ b/arch/arm64/include/asm/mmu.h
@@ -70,7 +70,6 @@ extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
pgprot_t prot, bool page_mappings_only);
extern void *fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot);
extern void mark_linear_text_alias_ro(void);
-extern bool kaslr_requires_kpti(void);

static inline unsigned long kaslr_offset(void)
{
diff --git a/arch/arm64/include/asm/scs.h b/arch/arm64/include/asm/scs.h
index bcf8ad574807b82c..f246b1515fd59507 100644
--- a/arch/arm64/include/asm/scs.h
+++ b/arch/arm64/include/asm/scs.h
@@ -33,37 +33,11 @@
#include <asm/cpufeature.h>

#ifdef CONFIG_UNWIND_PATCH_PAC_INTO_SCS
-static inline bool should_patch_pac_into_scs(void)
-{
- u64 reg;
-
- /*
- * We only enable the shadow call stack dynamically if we are running
- * on a system that does not implement PAC or BTI. PAC and SCS provide
- * roughly the same level of protection, and BTI relies on the PACIASP
- * instructions serving as landing pads, preventing us from patching
- * those instructions into something else.
- */
- reg = read_sysreg_s(SYS_ID_AA64ISAR1_EL1);
- if (SYS_FIELD_GET(ID_AA64ISAR1_EL1, APA, reg) |
- SYS_FIELD_GET(ID_AA64ISAR1_EL1, API, reg))
- return false;
-
- reg = read_sysreg_s(SYS_ID_AA64ISAR2_EL1);
- if (SYS_FIELD_GET(ID_AA64ISAR2_EL1, APA3, reg))
- return false;
-
- if (IS_ENABLED(CONFIG_ARM64_BTI_KERNEL)) {
- reg = read_sysreg_s(SYS_ID_AA64PFR1_EL1);
- if (reg & (0xf << ID_AA64PFR1_EL1_BT_SHIFT))
- return false;
- }
- return true;
-}
-
static inline void dynamic_scs_init(void)
{
- if (should_patch_pac_into_scs()) {
+ extern bool __pi_dynamic_scs_is_enabled;
+
+ if (__pi_dynamic_scs_is_enabled) {
pr_info("Enabling dynamic shadow call stack\n");
static_branch_enable(&dynamic_scs_enabled);
}
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 9838934fee028bcb..e9788671be044a47 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1607,7 +1607,7 @@ has_useable_cnp(const struct arm64_cpu_capabilities *entry, int scope)
* state once the SMP CPUs are up and thus make the switch to non-global
* mappings if required.
*/
-bool kaslr_requires_kpti(void)
+static bool kaslr_requires_kpti(void)
{
/*
* E0PD does a similar job to KPTI so can be used instead
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 81c2dd06420992ea..e45fd99e8ab4272a 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -81,7 +81,6 @@
* x20 primary_entry() .. __primary_switch() CPU boot mode
* x21 primary_entry() .. start_kernel() FDT pointer passed at boot in x0
* x22 create_idmap() .. start_kernel() ID map VA of the DT blob
- * x23 __primary_switch() physical misalignment/KASLR offset
* x25 primary_entry() .. start_kernel() supported VA size
* x28 create_idmap() callee preserved temp register
*/
@@ -408,24 +407,6 @@ SYM_FUNC_START_LOCAL(create_idmap)
0: ret x28
SYM_FUNC_END(create_idmap)

-SYM_FUNC_START_LOCAL(create_kernel_mapping)
- adrp x0, init_pg_dir
- mov_q x5, KIMAGE_VADDR // compile time __va(_text)
-#ifdef CONFIG_RELOCATABLE
- add x5, x5, x23 // add KASLR displacement
-#endif
- adrp x6, _end // runtime __pa(_end)
- adrp x3, _text // runtime __pa(_text)
- sub x6, x6, x3 // _end - _text
- add x6, x6, x5 // runtime __va(_end)
- mov x7, SWAPPER_RW_MMUFLAGS
-
- map_memory x0, x1, x5, x6, x7, x3, (VA_BITS - PGDIR_SHIFT), x10, x11, x12, x13, x14
-
- dsb ishst // sync with page table walker
- ret
-SYM_FUNC_END(create_kernel_mapping)
-
/*
* Initialize CPU registers with task-specific and cpu-specific context.
*
@@ -750,44 +731,13 @@ SYM_FUNC_START_LOCAL(__primary_switch)
adrp x2, init_idmap_pg_dir
bl __enable_mmu

- // Clear BSS
- adrp x0, __bss_start
- mov x1, xzr
- adrp x2, init_pg_end
- sub x2, x2, x0
- bl __pi_memset
- dsb ishst // Make zero page visible to PTW
-
adrp x1, early_init_stack
mov sp, x1
mov x29, xzr
mov x0, x20 // pass the full boot status
mov x1, x22 // pass the low FDT mapping
- bl __pi_init_feature_override // Parse cpu feature overrides
-
-#ifdef CONFIG_RELOCATABLE
- adrp x23, KERNEL_START
- and x23, x23, MIN_KIMG_ALIGN - 1
-#ifdef CONFIG_RANDOMIZE_BASE
- mov x0, x22
- bl __pi_kaslr_early_init
- bic x0, x0, #SZ_2M - 1
- orr x23, x23, x0 // record kernel offset
-#endif
-#endif
- bl create_kernel_mapping
+ bl __pi_early_map_kernel // Map and relocate the kernel

- adrp x1, init_pg_dir
- load_ttbr1 x1, x1, x2
-#ifdef CONFIG_RELOCATABLE
- mov x0, x23
- bl __pi_relocate_kernel
-#endif
-#ifdef CONFIG_UNWIND_PATCH_PAC_INTO_SCS
- ldr x0, =__eh_frame_start
- ldr x1, =__eh_frame_end
- bl __pi_scs_patch_vmlinux
-#endif
ldr x8, =__primary_switched
adrp x0, KERNEL_START // __pa(KERNEL_START)
br x8
diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index b7fa7fbf8fa543a6..6eeb2a09c8d2441d 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -43,9 +43,25 @@ PROVIDE(__pi_id_aa64pfr1_override = id_aa64pfr1_override);
PROVIDE(__pi_id_aa64smfr0_override = id_aa64smfr0_override);
PROVIDE(__pi_id_aa64zfr0_override = id_aa64zfr0_override);
PROVIDE(__pi_arm64_sw_feature_override = arm64_sw_feature_override);
+PROVIDE(__pi_arm64_use_ng_mappings = arm64_use_ng_mappings);
PROVIDE(__pi__ctype = _ctype);
PROVIDE(__pi_memstart_offset_seed = memstart_offset_seed);

+PROVIDE(__pi_init_pg_dir = init_pg_dir);
+PROVIDE(__pi_init_pg_end = init_pg_end);
+
+PROVIDE(__pi__text = _text);
+PROVIDE(__pi__stext = _stext);
+PROVIDE(__pi__etext = _etext);
+PROVIDE(__pi___start_rodata = __start_rodata);
+PROVIDE(__pi___inittext_begin = __inittext_begin);
+PROVIDE(__pi___inittext_end = __inittext_end);
+PROVIDE(__pi___initdata_begin = __initdata_begin);
+PROVIDE(__pi___initdata_end = __initdata_end);
+PROVIDE(__pi__data = _data);
+PROVIDE(__pi___bss_start = __bss_start);
+PROVIDE(__pi__end = _end);
+
#ifdef CONFIG_KVM

/*
diff --git a/arch/arm64/kernel/pi/Makefile b/arch/arm64/kernel/pi/Makefile
index a8b302245f15326a..8c2f80a46b9387b0 100644
--- a/arch/arm64/kernel/pi/Makefile
+++ b/arch/arm64/kernel/pi/Makefile
@@ -39,6 +39,7 @@ $(obj)/lib-%.o: $(srctree)/lib/%.c FORCE
$(call if_changed_rule,cc_o_c)

obj-y := idreg-override.pi.o \
+ map_kernel.pi.o map_range.pi.o \
lib-fdt.pi.o lib-fdt_ro.pi.o
obj-$(CONFIG_RELOCATABLE) += relocate.pi.o
obj-$(CONFIG_RANDOMIZE_BASE) += kaslr_early.pi.o
diff --git a/arch/arm64/kernel/pi/idreg-override.c b/arch/arm64/kernel/pi/idreg-override.c
index 6c547cccaf6a9e9c..265b35b09dd488f1 100644
--- a/arch/arm64/kernel/pi/idreg-override.c
+++ b/arch/arm64/kernel/pi/idreg-override.c
@@ -301,37 +301,35 @@ static __init void __parse_cmdline(const char *cmdline, bool parse_aliases)
} while (1);
}

-static __init const u8 *get_bootargs_cmdline(const void *fdt)
+static __init const u8 *get_bootargs_cmdline(const void *fdt, int node)
{
+ static char const bootargs[] __initconst = "bootargs";
const u8 *prop;
- int node;

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

- prop = fdt_getprop(fdt, node, "bootargs", NULL);
+ prop = fdt_getprop(fdt, node, bootargs, NULL);
if (!prop)
return NULL;

return strlen(prop) ? prop : NULL;
}

-static __init void parse_cmdline(const void *fdt)
+static __init void parse_cmdline(const void *fdt, int chosen)
{
- const u8 *prop = get_bootargs_cmdline(fdt);
+ static char const cmdline[] __initconst = CONFIG_CMDLINE;
+ const u8 *prop = get_bootargs_cmdline(fdt, chosen);

if (IS_ENABLED(CONFIG_CMDLINE_FORCE) || !prop)
- __parse_cmdline(CONFIG_CMDLINE, true);
+ __parse_cmdline(cmdline, true);

if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && prop)
__parse_cmdline(prop, true);
}

-/* Keep checkers quiet */
-void init_feature_override(u64 boot_status, const void *fdt);
-
-asmlinkage void __init init_feature_override(u64 boot_status, const void *fdt)
+void __init init_feature_override(u64 boot_status, const void *fdt,
+ int chosen)
{
struct arm64_ftr_override *override;
const struct ftr_set_desc *reg;
@@ -347,7 +345,7 @@ asmlinkage void __init init_feature_override(u64 boot_status, const void *fdt)

__boot_status = boot_status;

- parse_cmdline(fdt);
+ parse_cmdline(fdt, chosen);

for (i = 0; i < ARRAY_SIZE(regs); i++) {
reg = prel64_to_pointer(&regs[i].reg_prel);
diff --git a/arch/arm64/kernel/pi/kaslr_early.c b/arch/arm64/kernel/pi/kaslr_early.c
index eeecee7ffd6fa125..0257b43819db85eb 100644
--- a/arch/arm64/kernel/pi/kaslr_early.c
+++ b/arch/arm64/kernel/pi/kaslr_early.c
@@ -16,17 +16,17 @@
#include <asm/memory.h>
#include <asm/pgtable.h>

+#include "pi.h"
+
extern u16 memstart_offset_seed;

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

- node = fdt_path_offset(fdt, chosen_str);
if (node < 0)
return 0;

@@ -39,14 +39,14 @@ static u64 __init get_kaslr_seed(void *fdt)
return ret;
}

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

if (kaslr_disabled_cmdline())
return 0;

- seed = get_kaslr_seed(fdt);
+ seed = get_kaslr_seed(fdt, chosen);
if (!seed) {
if (!__early_cpu_has_rndr() ||
!__arm64_rndr((unsigned long *)&seed))
diff --git a/arch/arm64/kernel/pi/map_kernel.c b/arch/arm64/kernel/pi/map_kernel.c
new file mode 100644
index 0000000000000000..b573c964c7d88d1b
--- /dev/null
+++ b/arch/arm64/kernel/pi/map_kernel.c
@@ -0,0 +1,171 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright 2023 Google LLC
+// Author: Ard Biesheuvel <ardb@google.com>
+
+#include <linux/init.h>
+#include <linux/libfdt.h>
+#include <linux/linkage.h>
+#include <linux/types.h>
+#include <linux/sizes.h>
+#include <linux/string.h>
+
+#include <asm/memory.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+
+#include "pi.h"
+
+extern const u8 __eh_frame_start[], __eh_frame_end[];
+
+extern void idmap_cpu_replace_ttbr1(void *pgdir);
+
+static void map_segment(pgd_t *pg_dir, u64 *pgd, u64 va_offset,
+ void *start, void *end, pgprot_t prot,
+ bool may_use_cont, int root_level)
+{
+ map_range(pgd, ((u64)start + va_offset) & ~PAGE_OFFSET,
+ ((u64)end + va_offset) & ~PAGE_OFFSET, (u64)start,
+ prot, root_level, (pte_t *)pg_dir, may_use_cont, 0);
+}
+
+static void unmap_segment(pgd_t *pg_dir, u64 va_offset, void *start,
+ void *end, int root_level)
+{
+ map_segment(pg_dir, NULL, va_offset, start, end, __pgprot(0),
+ false, root_level);
+}
+
+static void __init map_kernel(u64 kaslr_offset, u64 va_offset, int root_level)
+{
+ bool enable_scs = IS_ENABLED(CONFIG_UNWIND_PATCH_PAC_INTO_SCS);
+ bool twopass = IS_ENABLED(CONFIG_RELOCATABLE);
+ u64 pgdp = (u64)init_pg_dir + PAGE_SIZE;
+ pgprot_t text_prot = PAGE_KERNEL_ROX;
+ pgprot_t data_prot = PAGE_KERNEL;
+ pgprot_t prot;
+
+ /*
+ * External debuggers may need to write directly to the text mapping to
+ * install SW breakpoints. Allow this (only) when explicitly requested
+ * with rodata=off.
+ */
+ if (cpuid_feature_extract_unsigned_field(arm64_sw_feature_override.val,
+ ARM64_SW_FEATURE_OVERRIDE_RODATA_OFF))
+ text_prot = PAGE_KERNEL_EXEC;
+
+ /*
+ * We only enable the shadow call stack dynamically if we are running
+ * on a system that does not implement PAC or BTI. PAC and SCS provide
+ * roughly the same level of protection, and BTI relies on the PACIASP
+ * instructions serving as landing pads, preventing us from patching
+ * those instructions into something else.
+ */
+ if (IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL) && cpu_has_pac())
+ enable_scs = false;
+
+ if (IS_ENABLED(CONFIG_ARM64_BTI_KERNEL) && cpu_has_bti()) {
+ enable_scs = false;
+
+ /*
+ * If we have a CPU that supports BTI and a kernel built for
+ * BTI then mark the kernel executable text as guarded pages
+ * now so we don't have to rewrite the page tables later.
+ */
+ text_prot = __pgprot_modify(text_prot, PTE_GP, PTE_GP);
+ }
+
+ /* Map all code read-write on the first pass if needed */
+ twopass |= enable_scs;
+ prot = twopass ? data_prot : text_prot;
+
+ map_segment(init_pg_dir, &pgdp, va_offset, _stext, _etext, prot,
+ !twopass, root_level);
+ map_segment(init_pg_dir, &pgdp, va_offset, __start_rodata,
+ __inittext_begin, data_prot, false, root_level);
+ map_segment(init_pg_dir, &pgdp, va_offset, __inittext_begin,
+ __inittext_end, prot, false, root_level);
+ map_segment(init_pg_dir, &pgdp, va_offset, __initdata_begin,
+ __initdata_end, data_prot, false, root_level);
+ map_segment(init_pg_dir, &pgdp, va_offset, _data, _end, data_prot,
+ true, root_level);
+ dsb(ishst);
+
+ idmap_cpu_replace_ttbr1(init_pg_dir);
+
+ if (twopass) {
+ if (IS_ENABLED(CONFIG_RELOCATABLE))
+ relocate_kernel(kaslr_offset);
+
+ if (enable_scs) {
+ scs_patch(__eh_frame_start + va_offset,
+ __eh_frame_end - __eh_frame_start);
+ asm("ic ialluis");
+
+ dynamic_scs_is_enabled = true;
+ }
+
+ /*
+ * Unmap the text region before remapping it, to avoid
+ * potential TLB conflicts when creating the contiguous
+ * descriptors.
+ */
+ unmap_segment(init_pg_dir, va_offset, _stext, _etext,
+ root_level);
+ dsb(ishst);
+ isb();
+ __tlbi(vmalle1);
+ isb();
+
+ /*
+ * Remap these segments with different permissions
+ * No new page table allocations should be needed
+ */
+ map_segment(init_pg_dir, NULL, va_offset, _stext, _etext,
+ text_prot, true, root_level);
+ map_segment(init_pg_dir, NULL, va_offset, __inittext_begin,
+ __inittext_end, text_prot, false, root_level);
+ dsb(ishst);
+ }
+}
+
+asmlinkage void __init early_map_kernel(u64 boot_status, void *fdt)
+{
+ static char const chosen_str[] __initconst = "/chosen";
+ u64 va_base, pa_base = (u64)&_text;
+ u64 kaslr_offset = pa_base % MIN_KIMG_ALIGN;
+ int root_level = 4 - CONFIG_PGTABLE_LEVELS;
+ int chosen;
+
+ /* Clear BSS and the initial page tables */
+ memset(__bss_start, 0, (u64)init_pg_end - (u64)__bss_start);
+
+ /* Parse the command line for CPU feature overrides */
+ chosen = fdt_path_offset(fdt, chosen_str);
+ init_feature_override(boot_status, fdt, chosen);
+
+ /*
+ * The virtual KASLR displacement modulo 2MiB is decided by the
+ * physical placement of the image, as otherwise, we might not be able
+ * to create the early kernel mapping using 2 MiB block descriptors. So
+ * take the low bits of the KASLR offset from the physical address, and
+ * fill in the high bits from the seed.
+ */
+ if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
+ u64 kaslr_seed = kaslr_early_init(fdt, chosen);
+
+ /*
+ * Assume that any CPU that does not implement E0PD needs KPTI
+ * to ensure that KASLR randomized addresses will not leak.
+ * This means we need to use non-global mappings for the kernel
+ * text and data.
+ */
+ if (kaslr_seed && !cpu_has_e0pd())
+ arm64_use_ng_mappings = true;
+
+ kaslr_offset |= kaslr_seed & ~(MIN_KIMG_ALIGN - 1);
+ }
+
+ va_base = KIMAGE_VADDR + kaslr_offset;
+ map_kernel(kaslr_offset, va_base - pa_base, root_level);
+}
diff --git a/arch/arm64/kernel/pi/map_range.c b/arch/arm64/kernel/pi/map_range.c
new file mode 100644
index 0000000000000000..61cbd6e82418c033
--- /dev/null
+++ b/arch/arm64/kernel/pi/map_range.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright 2023 Google LLC
+// Author: Ard Biesheuvel <ardb@google.com>
+
+#include <linux/types.h>
+#include <linux/sizes.h>
+
+#include <asm/memory.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+
+#include "pi.h"
+
+/**
+ * map_range - Map a contiguous range of physical pages into virtual memory
+ *
+ * @pte: Address of physical pointer to array of pages to
+ * allocate page tables from
+ * @start: Virtual address of the start of the range
+ * @end: Virtual address of the end of the range (exclusive)
+ * @pa: Physical address of the start of the range
+ * @level: Translation level for the mapping
+ * @tbl: The level @level page table to create the mappings in
+ * @may_use_cont: Whether the use of the contiguous attribute is allowed
+ * @va_offset: Offset between a physical page and its current mapping
+ * in the VA space
+ */
+void __init map_range(u64 *pte, u64 start, u64 end, u64 pa, pgprot_t prot,
+ int level, pte_t *tbl, bool may_use_cont, u64 va_offset)
+{
+ u64 cmask = (level == 3) ? CONT_PTE_SIZE - 1 : U64_MAX;
+ u64 protval = pgprot_val(prot) & ~PTE_TYPE_MASK;
+ int lshift = (3 - level) * (PAGE_SHIFT - 3);
+ u64 lmask = (PAGE_SIZE << lshift) - 1;
+
+ start &= PAGE_MASK;
+ pa &= PAGE_MASK;
+
+ /* Advance tbl to the entry that covers start */
+ tbl += (start >> (lshift + PAGE_SHIFT)) % PTRS_PER_PTE;
+
+ /*
+ * Set the right block/page bits for this level unless we are
+ * clearing the mapping
+ */
+ if (protval)
+ protval |= (level < 3) ? PMD_TYPE_SECT : PTE_TYPE_PAGE;
+
+ while (start < end) {
+ u64 next = min((start | lmask) + 1, PAGE_ALIGN(end));
+
+ if (level < 3 && (start | next | pa) & lmask) {
+ /*
+ * This chunk needs a finer grained mapping. Create a
+ * table mapping if necessary and recurse.
+ */
+ if (pte_none(*tbl)) {
+ *tbl = __pte(__phys_to_pte_val(*pte) |
+ PMD_TYPE_TABLE | PMD_TABLE_UXN);
+ *pte += PTRS_PER_PTE * sizeof(pte_t);
+ }
+ map_range(pte, start, next, pa, prot, level + 1,
+ (pte_t *)(__pte_to_phys(*tbl) + va_offset),
+ may_use_cont, va_offset);
+ } else {
+ /*
+ * Start a contiguous range if start and pa are
+ * suitably aligned
+ */
+ if (((start | pa) & cmask) == 0 && may_use_cont)
+ protval |= PTE_CONT;
+
+ /*
+ * Clear the contiguous attribute if the remaining
+ * range does not cover a contiguous block
+ */
+ if ((end & ~cmask) <= start)
+ protval &= ~PTE_CONT;
+
+ /* Put down a block or page mapping */
+ *tbl = __pte(__phys_to_pte_val(pa) | protval);
+ }
+ pa += next - start;
+ start = next;
+ tbl++;
+ }
+}
diff --git a/arch/arm64/kernel/pi/patch-scs.c b/arch/arm64/kernel/pi/patch-scs.c
index c65ef40d1e6b6b30..49d8b40e61bc050d 100644
--- a/arch/arm64/kernel/pi/patch-scs.c
+++ b/arch/arm64/kernel/pi/patch-scs.c
@@ -11,6 +11,10 @@

#include <asm/scs.h>

+#include "pi.h"
+
+bool dynamic_scs_is_enabled;
+
//
// This minimal DWARF CFI parser is partially based on the code in
// arch/arc/kernel/unwind.c, and on the document below:
@@ -46,8 +50,6 @@
#define DW_CFA_GNU_negative_offset_extended 0x2f
#define DW_CFA_hi_user 0x3f

-extern const u8 __eh_frame_start[], __eh_frame_end[];
-
enum {
PACIASP = 0xd503233f,
AUTIASP = 0xd50323bf,
@@ -250,13 +252,3 @@ int scs_patch(const u8 eh_frame[], int size)
}
return 0;
}
-
-asmlinkage void __init scs_patch_vmlinux(const u8 start[], const u8 end[])
-{
- if (!should_patch_pac_into_scs())
- return;
-
- scs_patch(start, end - start);
- asm("ic ialluis");
- isb();
-}
diff --git a/arch/arm64/kernel/pi/pi.h b/arch/arm64/kernel/pi/pi.h
index f455ad385976a664..dfc70828ad0ad2a8 100644
--- a/arch/arm64/kernel/pi/pi.h
+++ b/arch/arm64/kernel/pi/pi.h
@@ -2,6 +2,8 @@
// Copyright 2023 Google LLC
// Author: Ard Biesheuvel <ardb@google.com>

+#include <linux/types.h>
+
#define __prel64_initconst __section(".init.rodata.prel64")

typedef volatile signed long prel64_t;
@@ -12,3 +14,13 @@ static inline void *prel64_to_pointer(const prel64_t *offset)
return NULL;
return (void *)offset + *offset;
}
+
+extern bool dynamic_scs_is_enabled;
+
+void init_feature_override(u64 boot_status, const void *fdt, int chosen);
+u64 kaslr_early_init(void *fdt, int chosen);
+void relocate_kernel(u64 offset);
+int scs_patch(const u8 eh_frame[], int size);
+
+void map_range(u64 *pgd, u64 start, u64 end, u64 pa, pgprot_t prot,
+ int level, pte_t *tbl, bool may_use_cont, u64 va_offset);
diff --git a/arch/arm64/kernel/pi/relocate.c b/arch/arm64/kernel/pi/relocate.c
index 1853408ea76b0e5d..2407d269639870fc 100644
--- a/arch/arm64/kernel/pi/relocate.c
+++ b/arch/arm64/kernel/pi/relocate.c
@@ -7,6 +7,8 @@
#include <linux/init.h>
#include <linux/types.h>

+#include "pi.h"
+
extern const Elf64_Rela rela_start[], rela_end[];
extern const u64 relr_start[], relr_end[];

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index bda21a9245943c57..a4578c823ab57b6f 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -281,13 +281,6 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)

*cmdline_p = boot_command_line;

- /*
- * If know now we are going to need KPTI then use non-global
- * mappings from the start, avoiding the cost of rewriting
- * everything later.
- */
- arm64_use_ng_mappings = kaslr_requires_kpti();
-
early_fixmap_init();
early_ioremap_init();

diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index 6c79ad2945749260..e22bf17209c80ff9 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -126,9 +126,9 @@ jiffies = jiffies_64;
#ifdef CONFIG_UNWIND_TABLES
#define UNWIND_DATA_SECTIONS \
.eh_frame : { \
- __eh_frame_start = .; \
+ __pi___eh_frame_start = .; \
*(.eh_frame) \
- __eh_frame_end = .; \
+ __pi___eh_frame_end = .; \
}
#else
#define UNWIND_DATA_SECTIONS
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 91410f48809000a0..82e88f4521737c0e 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -195,6 +195,7 @@ SYM_TYPED_FUNC_START(idmap_cpu_replace_ttbr1)

ret
SYM_FUNC_END(idmap_cpu_replace_ttbr1)
+SYM_FUNC_ALIAS(__pi_idmap_cpu_replace_ttbr1, idmap_cpu_replace_ttbr1)
.popsection

#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
--
2.39.2