From: steve.capper@arm.com (Steve Capper)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH V2 1/2] arm64: Re-order reserved_ttbr0 in linker script
Date: Thu, 23 Nov 2017 16:40:39 +0000 [thread overview]
Message-ID: <20171123164040.31551-2-steve.capper@arm.com> (raw)
In-Reply-To: <20171123164040.31551-1-steve.capper@arm.com>
Currently one resolves the location of the reserved_ttbr0 for PAN by
taking a positive offset from swapper_pg_dir. In a future patch we wish
to extend the swapper s.t. its size is determined at link time rather
than compile time, rendering SWAPPER_DIR_SIZE unsuitable for such a low
level calculation.
In this patch we re-arrange the order of the linker script s.t. instead
one computes reserved_ttbr0 by subtracting RESERVED_TTBR0_SIZE from
swapper_pg_dir.
Signed-off-by: Steve Capper <steve.capper@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
---
arch/arm64/include/asm/asm-uaccess.h | 6 +++---
arch/arm64/include/asm/uaccess.h | 2 +-
arch/arm64/kernel/vmlinux.lds.S | 5 ++---
3 files changed, 6 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h
index b3da6c886835..e09f02cd3e7a 100644
--- a/arch/arm64/include/asm/asm-uaccess.h
+++ b/arch/arm64/include/asm/asm-uaccess.h
@@ -12,9 +12,9 @@
*/
#ifdef CONFIG_ARM64_SW_TTBR0_PAN
.macro __uaccess_ttbr0_disable, tmp1
- mrs \tmp1, ttbr1_el1 // swapper_pg_dir
- add \tmp1, \tmp1, #SWAPPER_DIR_SIZE // reserved_ttbr0 at the end of swapper_pg_dir
- msr ttbr0_el1, \tmp1 // set reserved TTBR0_EL1
+ mrs \tmp1, ttbr1_el1 // swapper_pg_dir
+ sub \tmp1, \tmp1, #RESERVED_TTBR0_SIZE // reserved_ttbr0 just before swapper_pg_dir
+ msr ttbr0_el1, \tmp1 // set reserved TTBR0_EL1
isb
.endm
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index fc0f9eb66039..66170fd4b58f 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -108,7 +108,7 @@ static inline void __uaccess_ttbr0_disable(void)
unsigned long ttbr;
/* reserved_ttbr0 placed at the end of swapper_pg_dir */
- ttbr = read_sysreg(ttbr1_el1) + SWAPPER_DIR_SIZE;
+ ttbr = read_sysreg(ttbr1_el1) - RESERVED_TTBR0_SIZE;
write_sysreg(ttbr, ttbr0_el1);
isb();
}
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index 7da3e5c366a0..2a9475733e84 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -206,13 +206,12 @@ SECTIONS
. = ALIGN(PAGE_SIZE);
idmap_pg_dir = .;
. += IDMAP_DIR_SIZE;
- swapper_pg_dir = .;
- . += SWAPPER_DIR_SIZE;
-
#ifdef CONFIG_ARM64_SW_TTBR0_PAN
reserved_ttbr0 = .;
. += RESERVED_TTBR0_SIZE;
#endif
+ swapper_pg_dir = .;
+ . += SWAPPER_DIR_SIZE;
__pecoff_data_size = ABSOLUTE(. - __initdata_begin);
_end = .;
--
2.11.0
next prev parent reply other threads:[~2017-11-23 16:40 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-23 16:40 [PATCH V2 0/2] Map larger kernels at early init Steve Capper
2017-11-23 16:40 ` Steve Capper [this message]
2017-12-04 14:13 ` [PATCH V2 1/2] arm64: Re-order reserved_ttbr0 in linker script Ard Biesheuvel
2017-12-12 10:51 ` Steve Capper
2017-11-23 16:40 ` [PATCH V2 2/2] arm64: Extend early page table code to allow for larger kernels Steve Capper
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