linux-kernel - [PATCH 4.18 04/22] x86/mm/init: Pass unconverted symbol addresses to free_init

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Message-Id: <20180823074759.458406474@linuxfoundation.org>
Date:   Thu, 23 Aug 2018 09:56:30 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dave Hansen <dave.hansen@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>, keescook@...gle.com,
        aarcange@...hat.com, jgross@...e.com, jpoimboe@...hat.com,
        peterz@...radead.org, hughd@...gle.com,
        torvalds@...ux-foundation.org, bp@...en8.de, luto@...nel.org,
        ak@...ux.intel.com
Subject: [PATCH 4.18 04/22] x86/mm/init: Pass unconverted symbol addresses to free_init_pages()

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dave Hansen <dave.hansen@...ux.intel.com>

commit 9f515cdb411ef34f1aaf4c40bb0c932cf6db5de1 upstream.

The x86 code has several places where it frees parts of kernel image:

 1. Unused SMP alternative
 2. __init code
 3. The hole between text and rodata
 4. The hole between rodata and data

We call free_init_pages() to do this.  Strangely, we convert the symbol
addresses to kernel direct map addresses in some cases (#3, #4) but not
others (#1, #2).

The virt_to_page() and the other code in free_reserved_area() now works
fine for for symbol addresses on x86, so don't bother converting the
addresses to direct map addresses before freeing them.

Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: keescook@...gle.com
Cc: aarcange@...hat.com
Cc: jgross@...e.com
Cc: jpoimboe@...hat.com
Cc: gregkh@...uxfoundation.org
Cc: peterz@...radead.org
Cc: hughd@...gle.com
Cc: torvalds@...ux-foundation.org
Cc: bp@...en8.de
Cc: luto@...nel.org
Cc: ak@...ux.intel.com
Cc: Kees Cook <keescook@...gle.com>
Cc: Andrea Arcangeli <aarcange@...hat.com>
Cc: Juergen Gross <jgross@...e.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Hugh Dickins <hughd@...gle.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Andi Kleen <ak@...ux.intel.com>
Link: https://lkml.kernel.org/r/20180802225828.89B2D0E2@viggo.jf.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/mm/init_64.c |    8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -1283,12 +1283,8 @@ void mark_rodata_ro(void)
 	set_memory_ro(start, (end-start) >> PAGE_SHIFT);
 #endif
 
-	free_init_pages("unused kernel",
-			(unsigned long) __va(__pa_symbol(text_end)),
-			(unsigned long) __va(__pa_symbol(rodata_start)));
-	free_init_pages("unused kernel",
-			(unsigned long) __va(__pa_symbol(rodata_end)),
-			(unsigned long) __va(__pa_symbol(_sdata)));
+	free_init_pages("unused kernel", text_end, rodata_start);
+	free_init_pages("unused kernel", rodata_end, _sdata);
 
 	debug_checkwx();