On 2023-03-10 17:52, Ard Biesheuvel wrote:
On Thu, 15 Dec 2022 at 13:40, Evgeniy Baskov <baskov@xxxxxxxxx> wrote:
Convert kernel_add_identity_map() into a function pointer to be able
to provide alternative implementations of this function. Required
to enable calling the code using this function from EFI environment.
Tested-by: Mario Limonciello <mario.limonciello@xxxxxxx>
Tested-by: Peter Jones <pjones@xxxxxxxxxx>
Signed-off-by: Evgeniy Baskov <baskov@xxxxxxxxx>
---
arch/x86/boot/compressed/ident_map_64.c | 7 ++++---
arch/x86/boot/compressed/misc.c | 24 ++++++++++++++++++++++++
arch/x86/boot/compressed/misc.h | 15 +++------------
3 files changed, 31 insertions(+), 15 deletions(-)
diff --git a/arch/x86/boot/compressed/ident_map_64.c
b/arch/x86/boot/compressed/ident_map_64.c
index ba5108c58a4e..1aee524d3c2b 100644
--- a/arch/x86/boot/compressed/ident_map_64.c
+++ b/arch/x86/boot/compressed/ident_map_64.c
@@ -92,9 +92,9 @@ bool has_nx; /* set in head_64.S */
/*
* Adds the specified range to the identity mappings.
*/
-unsigned long kernel_add_identity_map(unsigned long start,
- unsigned long end,
- unsigned int flags)
+unsigned long kernel_add_identity_map_(unsigned long start,
Please use a more discriminating name here - the trailing _ is rather
hard to spot.
Got it. The kernel_add_identity_map_impl() will fit better, I think.
+ unsigned long end,
+ unsigned int flags)
{
int ret;
@@ -142,6 +142,7 @@ void initialize_identity_maps(void *rmode)
struct setup_data *sd;
boot_params = rmode;
+ kernel_add_identity_map = kernel_add_identity_map_;
/* Exclude the encryption mask from __PHYSICAL_MASK */
physical_mask &= ~sme_me_mask;
diff --git a/arch/x86/boot/compressed/misc.c
b/arch/x86/boot/compressed/misc.c
index aa4a22bc9cf9..c9c235d65d16 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -275,6 +275,22 @@ static void parse_elf(void *output, unsigned long
output_len,
free(phdrs);
}
+/*
+ * This points to actual implementation of mapping function
+ * for current environment: either EFI API wrapper,
+ * own implementation or dummy implementation below.
+ */
+unsigned long (*kernel_add_identity_map)(unsigned long start,
+ unsigned long end,
+ unsigned int flags);
+
+static inline unsigned long kernel_add_identity_map_dummy(unsigned
long start,
This function is never called, it only has its address taken, so the
'inline' makes no sense here.
Indeed. I'll remove the inline.
+ unsigned
long end,
+ unsigned int
flags)
+{
+ return start;
+}
+
/*
* The compressed kernel image (ZO), has been moved so that its
position
* is against the end of the buffer used to hold the uncompressed
kernel
@@ -312,6 +328,14 @@ asmlinkage __visible void *extract_kernel(void
*rmode, memptr heap,
init_default_io_ops();
+ /*
+ * On 64-bit this pointer is set during page table
uninitialization,
initialization
Thanks!
+ * but on 32-bit it remains uninitialized, since paging is
disabled.
+ */
+ if (IS_ENABLED(CONFIG_X86_32))
+ kernel_add_identity_map =
kernel_add_identity_map_dummy;
+
+
/*
* Detect TDX guest environment.
*
diff --git a/arch/x86/boot/compressed/misc.h
b/arch/x86/boot/compressed/misc.h
index 38d31bec062d..0076b2845b4b 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -180,18 +180,9 @@ static inline int
count_immovable_mem_regions(void) { return 0; }
#ifdef CONFIG_X86_5LEVEL
extern unsigned int __pgtable_l5_enabled, pgdir_shift, ptrs_per_p4d;
#endif
-#ifdef CONFIG_X86_64
-extern unsigned long kernel_add_identity_map(unsigned long start,
- unsigned long end,
- unsigned int flags);
-#else
-static inline unsigned long kernel_add_identity_map(unsigned long
start,
- unsigned long end,
- unsigned int
flags)
-{
- return start;
-}
-#endif
+extern unsigned long (*kernel_add_identity_map)(unsigned long start,
+ unsigned long end,
+ unsigned int flags);
/* Used by PAGE_KERN* macros: */
extern pteval_t __default_kernel_pte_mask;
--
2.37.4
