From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Mark Rutland <mark.rutland@arm.com>,
Will Deacon <will.deacon@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>
Subject: [ 01/21] arm64: debug: clear mdscr_el1 instead of taking the OS lock
Date: Wed, 22 May 2013 15:10:19 -0700 [thread overview]
Message-ID: <20130522205232.804536363@linuxfoundation.org> (raw)
In-Reply-To: <20130522205232.597066680@linuxfoundation.org>
3.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Will Deacon <will.deacon@arm.com>
commit 9c413e25d95fd3c0abe23eadad66191b22baa549 upstream.
During boot, we take the debug OS lock before interrupts are enabled.
This is required to prevent clearing of PSTATE.D on the interrupt entry
path, which could result in spurious debug exceptions before we've got
round to resetting things like the hardware breakpoints registers to a
sane state.
A problem with this approach is that taking the OS lock prevents an
external JTAG debugger from debugging the system, which is especially
irritating during boot, where JTAG debugging can be most useful.
This patch clears mdscr_el1 rather than taking the lock, clearing the
MDE and KDE bits and preventing self-hosted hardware debug exceptions
from occurring.
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/kernel/debug-monitors.c | 2 --
arch/arm64/mm/proc.S | 3 +--
2 files changed, 1 insertion(+), 4 deletions(-)
--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -136,8 +136,6 @@ void disable_debug_monitors(enum debug_e
*/
static void clear_os_lock(void *unused)
{
- asm volatile("msr mdscr_el1, %0" : : "r" (0));
- isb();
asm volatile("msr oslar_el1, %0" : : "r" (0));
isb();
}
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -119,8 +119,7 @@ ENTRY(__cpu_setup)
mov x0, #3 << 20
msr cpacr_el1, x0 // Enable FP/ASIMD
- mov x0, #1
- msr oslar_el1, x0 // Set the debug OS lock
+ msr mdscr_el1, xzr // Reset mdscr_el1
tlbi vmalle1is // invalidate I + D TLBs
/*
* Memory region attributes for LPAE:
next prev parent reply other threads:[~2013-05-22 22:10 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-22 22:10 [ 00/21] 3.9.4-stable review Greg Kroah-Hartman
2013-05-22 22:10 ` Greg Kroah-Hartman [this message]
2013-05-22 22:10 ` [ 02/21] arm64: mm: Fix operands of clz in __flush_dcache_all Greg Kroah-Hartman
2013-05-22 22:10 ` [ 03/21] btrfs: dont stop searching after encountering the wrong item Greg Kroah-Hartman
2013-05-22 22:10 ` [ 04/21] hwmon: fix error return code in abituguru_probe() Greg Kroah-Hartman
2013-05-22 22:10 ` [ 05/21] i2c: designware: fix RX FIFO overrun Greg Kroah-Hartman
2013-05-22 22:10 ` [ 06/21] i2c: designware: always clear interrupts before enabling them Greg Kroah-Hartman
2013-05-22 22:10 ` [ 07/21] x86: Fix bit corruption at CPU resume time Greg Kroah-Hartman
2013-05-22 22:10 ` [ 08/21] drm/nouveau/bios: fix thinko in ZM_MASK_ADD opcode Greg Kroah-Hartman
2013-05-22 22:10 ` [ 09/21] drm/radeon: Fix VRAM size calculation for VRAM >= 4GB Greg Kroah-Hartman
2013-05-22 22:10 ` [ 10/21] virtio_console: fix uapi header Greg Kroah-Hartman
2013-05-22 22:10 ` [ 11/21] NTB: variable dereferenced before check Greg Kroah-Hartman
2013-05-22 22:10 ` [ 12/21] ntb: off by one sanity checks Greg Kroah-Hartman
2013-05-22 22:10 ` [ 13/21] NTB: fix pointer math issues Greg Kroah-Hartman
2013-05-22 22:10 ` [ 14/21] NTB: Handle 64bit BAR sizes Greg Kroah-Hartman
2013-05-22 22:10 ` [ 15/21] NTB: Link toggle memory leak Greg Kroah-Hartman
2013-05-22 22:10 ` [ 16/21] NTB: reset tx_index on link toggle Greg Kroah-Hartman
2013-05-22 22:10 ` [ 17/21] NTB: Correctly handle receive buffers of the minimal size Greg Kroah-Hartman
2013-05-22 22:10 ` [ 18/21] NTB: memcpy lockup workaround Greg Kroah-Hartman
2013-05-22 22:10 ` [ 19/21] ntb_netdev: remove from list on exit Greg Kroah-Hartman
2013-05-22 22:10 ` [ 20/21] NTB: Multiple NTB client fix Greg Kroah-Hartman
2013-05-22 22:10 ` [ 21/21] x86, vm86: fix VM86 syscalls: use SYSCALL_DEFINEx(...) Greg Kroah-Hartman
2013-05-24 11:13 ` Satoru Takeuchi
2013-05-23 16:52 ` [ 00/21] 3.9.4-stable review Shuah Khan
2013-05-23 16:57 ` Greg Kroah-Hartman
2013-05-24 11:46 ` Satoru Takeuchi
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