[PATCH 5.16 27/37] arm64: entry: Allow the trampoline text to occupy multiple pages

Greg Kroah-Hartman
2022-03-09T16:21:55Z

From: James Morse <james.morse@arm.com>

commit a9c406e6462ff14956d690de7bbe5131a5677dc9 upstream.

Adding a second set of vectors to .entry.tramp.text will make it
larger than a single 4K page.

Allow the trampoline text to occupy up to three pages by adding two
more fixmap slots. Previous changes to tramp_valias allowed it to reach
beyond a single page.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/include/asm/fixmap.h | 6 ++++--
arch/arm64/include/asm/sections.h | 5 +++++
arch/arm64/kernel/entry.S | 2 +-
arch/arm64/kernel/vmlinux.lds.S | 2 +-
arch/arm64/mm/mmu.c | 12 +++++++++---
5 files changed, 20 insertions(+), 7 deletions(-)

--- a/arch/arm64/include/asm/fixmap.h
+++ b/arch/arm64/include/asm/fixmap.h
@@ -62,9 +62,11 @@ enum fixed_addresses {
#endif /* CONFIG_ACPI_APEI_GHES */

#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
- FIX_ENTRY_TRAMP_TEXT,
+ FIX_ENTRY_TRAMP_TEXT3,
+ FIX_ENTRY_TRAMP_TEXT2,
+ FIX_ENTRY_TRAMP_TEXT1,
FIX_ENTRY_TRAMP_DATA,
-#define TRAMP_VALIAS (__fix_to_virt(FIX_ENTRY_TRAMP_TEXT))
+#define TRAMP_VALIAS (__fix_to_virt(FIX_ENTRY_TRAMP_TEXT1))
#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */
__end_of_permanent_fixed_addresses,

--- a/arch/arm64/include/asm/sections.h
+++ b/arch/arm64/include/asm/sections.h
@@ -23,4 +23,9 @@ extern char __mmuoff_data_start[], __mmu
extern char __entry_tramp_text_start[], __entry_tramp_text_end[];
extern char __relocate_new_kernel_start[], __relocate_new_kernel_end[];

+static inline size_t entry_tramp_text_size(void)
+{
+ return __entry_tramp_text_end - __entry_tramp_text_start;
+}
+
#endif /* __ASM_SECTIONS_H */
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -642,7 +642,7 @@ alternative_else_nop_endif
.endm

.macro tramp_data_page dst
- adr \dst, .entry.tramp.text
+ adr_l \dst, .entry.tramp.text
sub \dst, \dst, PAGE_SIZE
.endm

--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -341,7 +341,7 @@ ASSERT(__hibernate_exit_text_end - (__hi
<= SZ_4K, "Hibernate exit text too big or misaligned")
#endif
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
-ASSERT((__entry_tramp_text_end - __entry_tramp_text_start) == PAGE_SIZE,
+ASSERT((__entry_tramp_text_end - __entry_tramp_text_start) <= 3*PAGE_SIZE,
"Entry trampoline text too big")
#endif
#ifdef CONFIG_KVM
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -617,6 +617,8 @@ early_param("rodata", parse_rodata);
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
static int __init map_entry_trampoline(void)
{
+ int i;
+
pgprot_t prot = rodata_enabled ? PAGE_KERNEL_ROX : PAGE_KERNEL_EXEC;
phys_addr_t pa_start = __pa_symbol(__entry_tramp_text_start);

@@ -625,11 +627,15 @@ static int __init map_entry_trampoline(v

/* Map only the text into the trampoline page table */
memset(tramp_pg_dir, 0, PGD_SIZE);
- __create_pgd_mapping(tramp_pg_dir, pa_start, TRAMP_VALIAS, PAGE_SIZE,
- prot, __pgd_pgtable_alloc, 0);
+ __create_pgd_mapping(tramp_pg_dir, pa_start, TRAMP_VALIAS,
+ entry_tramp_text_size(), prot,
+ __pgd_pgtable_alloc, NO_BLOCK_MAPPINGS);

/* Map both the text and data into the kernel page table */
- __set_fixmap(FIX_ENTRY_TRAMP_TEXT, pa_start, prot);
+ for (i = 0; i < DIV_ROUND_UP(entry_tramp_text_size(), PAGE_SIZE); i++)
+ __set_fixmap(FIX_ENTRY_TRAMP_TEXT1 - i,
+ pa_start + i * PAGE_SIZE, prot);
+
if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
extern char __entry_tramp_data_start[];