[PATCH 3/5] x86/boot/64: Change add_identity_map() to take size for ease of use

Arvind Sankar
2020-10-07T19:54:00Z

Change back the arguments of add_identity_map() to (start, size) instead
of (start, end). This reverts

21cf2372618e ("x86/boot/compressed/64: Change add_identity_map() to take start and end")

since we will soon have more callers that know the size rather than the
end address.

This also makes the #PF handler print the original CR2 value in case of
error, instead of after aligning to PMD_SIZE.

Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
---
arch/x86/boot/compressed/ident_map_64.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/arch/x86/boot/compressed/ident_map_64.c b/arch/x86/boot/compressed/ident_map_64.c
index 063a60edcf99..070cda70aef3 100644
--- a/arch/x86/boot/compressed/ident_map_64.c
+++ b/arch/x86/boot/compressed/ident_map_64.c
@@ -90,8 +90,9 @@ static struct x86_mapping_info mapping_info;
/*
* Adds the specified range to the identity mappings.
*/
-static void add_identity_map(unsigned long start, unsigned long end)
+static void add_identity_map(unsigned long start, unsigned long size)
{
+ unsigned long end = start + size;
int ret;

/* Align boundary to 2M. */
@@ -152,7 +153,7 @@ void initialize_identity_maps(void)
* New page-table is set up - map the kernel image and load it
* into cr3.
*/
- add_identity_map((unsigned long)_head, (unsigned long)_end);
+ add_identity_map((unsigned long)_head, (unsigned long)_end - (unsigned long)_head);
write_cr3(top_level_pgt);
}

@@ -322,14 +323,10 @@ static void do_pf_error(const char *msg, unsigned long error_code,
void do_boot_page_fault(struct pt_regs *regs, unsigned long error_code)
{
unsigned long address = native_read_cr2();
- unsigned long end;
bool ghcb_fault;

ghcb_fault = sev_es_check_ghcb_fault(address);

- address &= PMD_MASK;
- end = address + PMD_SIZE;
-
/*
* Check for unexpected error codes. Unexpected are:
* - Faults on present pages
@@ -345,5 +342,5 @@ void do_boot_page_fault(struct pt_regs *regs, unsigned long error_code)
* Error code is sane - now identity map the 2M region around
* the faulting address.
*/
- add_identity_map(address, end);
+ add_identity_map(address & PMD_MASK, PMD_SIZE);
}
--
2.26.2