[PATCH 01/12] x86/efi: Clean up efi CR3 save/restore

Ard Biesheuvel
2017-04-04T16:03:17Z

From: Andy Lutomirski <luto@kernel.org>

efi_call_phys_prolog() used to return a "pgd_t *" that meant one of
three different things depending on kernel and system configuration.
Clean it up so it uses a union and is more explicit about what's
going on.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
arch/x86/include/asm/efi.h | 17 +++++++++++++++--
arch/x86/platform/efi/efi.c | 6 +++---
arch/x86/platform/efi/efi_32.c | 12 ++++++------
arch/x86/platform/efi/efi_64.c | 22 ++++++++++++----------
4 files changed, 36 insertions(+), 21 deletions(-)

diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 2f77bcefe6b4..6d74cc3802e6 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -111,11 +111,24 @@ extern void __iomem *__init efi_ioremap(unsigned long addr, unsigned long size,

#endif /* CONFIG_X86_32 */

+union efi_saved_pgd {
+ /*
+ * If !EFI_OLD_MEMMAP or we're 32-bit, this is a verbatim saved CR3
+ * value.
+ */
+ unsigned long cr3;
+
+#ifdef CONFIG_X86_64
+ /* If EFI_OLD_MEMMAP, this is a kmalloced copy of the pgd. */
+ pgd_t *pgd;
+#endif
+};
+
extern struct efi_scratch efi_scratch;
extern void __init efi_set_executable(efi_memory_desc_t *md, bool executable);
extern int __init efi_memblock_x86_reserve_range(void);
-extern pgd_t * __init efi_call_phys_prolog(void);
-extern void __init efi_call_phys_epilog(pgd_t *save_pgd);
+extern union efi_saved_pgd __init efi_call_phys_prolog(void);
+extern void __init efi_call_phys_epilog(union efi_saved_pgd saved_pgd);
extern void __init efi_print_memmap(void);
extern void __init efi_memory_uc(u64 addr, unsigned long size);
extern void __init efi_map_region(efi_memory_desc_t *md);
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 565dff3c9a12..217dc166c649 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -81,9 +81,9 @@ static efi_status_t __init phys_efi_set_virtual_address_map(
{
efi_status_t status;
unsigned long flags;
- pgd_t *save_pgd;
+ union efi_saved_pgd saved_pgd;

- save_pgd = efi_call_phys_prolog();
+ saved_pgd = efi_call_phys_prolog();

/* Disable interrupts around EFI calls: */
local_irq_save(flags);
@@ -92,7 +92,7 @@ static efi_status_t __init phys_efi_set_virtual_address_map(
descriptor_version, virtual_map);
local_irq_restore(flags);

- efi_call_phys_epilog(save_pgd);
+ efi_call_phys_epilog(saved_pgd);

return status;
}
diff --git a/arch/x86/platform/efi/efi_32.c b/arch/x86/platform/efi/efi_32.c
index cef39b097649..9b1abcf6e7bb 100644
--- a/arch/x86/platform/efi/efi_32.c
+++ b/arch/x86/platform/efi/efi_32.c
@@ -58,13 +58,13 @@ void __init efi_map_region(efi_memory_desc_t *md)
void __init efi_map_region_fixed(efi_memory_desc_t *md) {}
void __init parse_efi_setup(u64 phys_addr, u32 data_len) {}

-pgd_t * __init efi_call_phys_prolog(void)
+union efi_saved_pgd __init efi_call_phys_prolog(void)
{
struct desc_ptr gdt_descr;
- pgd_t *save_pgd;
+ union efi_saved_pgd saved_pgd;

/* Current pgd is swapper_pg_dir, we'll restore it later: */
- save_pgd = swapper_pg_dir;
+ saved_pgd.cr3 = __pa(swapper_pg_dir);
load_cr3(initial_page_table);
__flush_tlb_all();

@@ -72,10 +72,10 @@ pgd_t * __init efi_call_phys_prolog(void)
gdt_descr.size = GDT_SIZE - 1;
load_gdt(&gdt_descr);

- return save_pgd;
+ return saved_pgd;
}

-void __init efi_call_phys_epilog(pgd_t *save_pgd)
+void __init efi_call_phys_epilog(union efi_saved_pgd saved_pgd)
{
struct desc_ptr gdt_descr;

@@ -83,7 +83,7 @@ void __init efi_call_phys_epilog(pgd_t *save_pgd)
gdt_descr.size = GDT_SIZE - 1;
load_gdt(&gdt_descr);

- load_cr3(save_pgd);
+ write_cr3(saved_pgd.cr3);
__flush_tlb_all();
}

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index a4695da42d77..d56dd864fb1c 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -69,16 +69,16 @@ static void __init early_code_mapping_set_exec(int executable)
}
}

-pgd_t * __init efi_call_phys_prolog(void)
+union efi_saved_pgd __init efi_call_phys_prolog(void)
{
unsigned long vaddress;
- pgd_t *save_pgd;
+ union efi_saved_pgd saved_pgd;

int pgd;
int n_pgds;

if (!efi_enabled(EFI_OLD_MEMMAP)) {
- save_pgd = (pgd_t *)read_cr3();
+ saved_pgd.cr3 = read_cr3();
write_cr3((unsigned long)efi_scratch.efi_pgt);
goto out;
}
@@ -86,20 +86,21 @@ pgd_t * __init efi_call_phys_prolog(void)
early_code_mapping_set_exec(1);

n_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT), PGDIR_SIZE);
- save_pgd = kmalloc_array(n_pgds, sizeof(*save_pgd), GFP_KERNEL);
+ saved_pgd.pgd = kmalloc_array(n_pgds, sizeof(*saved_pgd.pgd),
+ GFP_KERNEL);

for (pgd = 0; pgd < n_pgds; pgd++) {
- save_pgd[pgd] = *pgd_offset_k(pgd * PGDIR_SIZE);
+ saved_pgd.pgd[pgd] = *pgd_offset_k(pgd * PGDIR_SIZE);
vaddress = (unsigned long)__va(pgd * PGDIR_SIZE);
set_pgd(pgd_offset_k(pgd * PGDIR_SIZE), *pgd_offset_k(vaddress));
}
out:
__flush_tlb_all();

- return save_pgd;
+ return saved_pgd;
}

-void __init efi_call_phys_epilog(pgd_t *save_pgd)
+void __init efi_call_phys_epilog(union efi_saved_pgd saved_pgd)
{
/*
* After the lock is released, the original page table is restored.
@@ -108,7 +109,7 @@ void __init efi_call_phys_epilog(pgd_t *save_pgd)
int nr_pgds;

if (!efi_enabled(EFI_OLD_MEMMAP)) {
- write_cr3((unsigned long)save_pgd);
+ write_cr3(saved_pgd.cr3);
__flush_tlb_all();
return;
}
@@ -116,9 +117,10 @@ void __init efi_call_phys_epilog(pgd_t *save_pgd)
nr_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT) , PGDIR_SIZE);

for (pgd_idx = 0; pgd_idx < nr_pgds; pgd_idx++)
- set_pgd(pgd_offset_k(pgd_idx * PGDIR_SIZE), save_pgd[pgd_idx]);
+ set_pgd(pgd_offset_k(pgd_idx * PGDIR_SIZE),
+ saved_pgd.pgd[pgd_idx]);

- kfree(save_pgd);
+ kfree(saved_pgd.pgd);

__flush_tlb_all();
early_code_mapping_set_exec(0);
--
2.9.3