linux-kernel - [PATCH v3 18/75] x86/boot/compressed/64: Change add_identity

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Message-Id: <20200428151725.31091-19-joro@8bytes.org>
Date:   Tue, 28 Apr 2020 17:16:28 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     x86@...nel.org
Cc:     hpa@...or.com, Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Hellstrom <thellstrom@...are.com>,
        Jiri Slaby <jslaby@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Juergen Gross <jgross@...e.com>,
        Kees Cook <keescook@...omium.org>,
        David Rientjes <rientjes@...gle.com>,
        Cfir Cohen <cfir@...gle.com>,
        Erdem Aktas <erdemaktas@...gle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Mike Stunes <mstunes@...are.com>,
        Joerg Roedel <joro@...tes.org>, Joerg Roedel <jroedel@...e.de>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org
Subject: [PATCH v3 18/75] x86/boot/compressed/64: Change add_identity_map() to take start and end

From: Joerg Roedel <jroedel@...e.de>

Changing the function to take start and end as parameters instead of
start and size simplifies the callers, which don't need to calculate
the size if they already have start and end.

Signed-off-by: Joerg Roedel <jroedel@...e.de>
---
 arch/x86/boot/compressed/ident_map_64.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/arch/x86/boot/compressed/ident_map_64.c b/arch/x86/boot/compressed/ident_map_64.c
index 9f6606184797..83385a551f01 100644
--- a/arch/x86/boot/compressed/ident_map_64.c
+++ b/arch/x86/boot/compressed/ident_map_64.c
@@ -91,10 +91,8 @@ 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 size)
+static void add_identity_map(unsigned long start, unsigned long end)
 {
-	unsigned long end = start + size;
-
 	/* Align boundary to 2M. */
 	start = round_down(start, PMD_SIZE);
 	end = round_up(end, PMD_SIZE);
@@ -109,8 +107,6 @@ static void add_identity_map(unsigned long start, unsigned long size)
 /* Locates and clears a region for a new top level page table. */
 void initialize_identity_maps(void)
 {
-	unsigned long start, size;
-
 	/* If running as an SEV guest, the encryption mask is required. */
 	set_sev_encryption_mask();
 
@@ -157,15 +153,14 @@ void initialize_identity_maps(void)
 	 * New page-table is set up - map the kernel image and load it
 	 * into cr3.
 	 */
-	start = (unsigned long)_head;
-	size  = _end - _head;
-	add_identity_map(start, size);
+	add_identity_map((unsigned long)_head, (unsigned long)_end);
 	write_cr3(top_level_pgt);
 }
 
 void do_boot_page_fault(struct pt_regs *regs, unsigned long error_code)
 {
-	unsigned long address = native_read_cr2();
+	unsigned long address = native_read_cr2() & PMD_MASK;
+	unsigned long end = address + PMD_SIZE;
 
 	/*
 	 * Check for unexpected error codes. Unexpected are:
@@ -191,5 +186,5 @@ 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 & PMD_MASK, PMD_SIZE);
+	add_identity_map(address, end);
 }
-- 
2.17.1