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authorGeert Uytterhoeven <geert@linux-m68k.org>2014-09-28 10:50:06 +0200
committerGeert Uytterhoeven <geert@linux-m68k.org>2014-10-03 10:50:56 +0200
commite4dc601bf99ccd1c95b7e6eef1d3cf3c4b0d4961 (patch)
tree53d8c0365752e85cfe8491a91265944d64188cef /arch
parentfd4d453b64d409647c92de6395494b5dd82ce224 (diff)
downloadlinux-e4dc601bf99ccd1c95b7e6eef1d3cf3c4b0d4961.tar.gz
m68k: Disable/restore interrupts in hwreg_present()/hwreg_write()
hwreg_present() and hwreg_write() temporarily change the VBR register to another vector table. This table contains a valid bus error handler only, all other entries point to arbitrary addresses. If an interrupt comes in while the temporary table is active, the processor will start executing at such an arbitrary address, and the kernel will crash. While most callers run early, before interrupts are enabled, or explicitly disable interrupts, Finn Thain pointed out that macsonic has one callsite that doesn't, causing intermittent boot crashes. There's another unsafe callsite in hilkbd. Fix this for good by disabling and restoring interrupts inside hwreg_present() and hwreg_write(). Explicitly disabling interrupts can be removed from the callsites later. Reported-by: Finn Thain <fthain@telegraphics.com.au> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> Cc: stable@vger.kernel.org
Diffstat (limited to 'arch')
-rw-r--r--arch/m68k/mm/hwtest.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/m68k/mm/hwtest.c b/arch/m68k/mm/hwtest.c
index 2c7dde3c6430..2a5259fd23eb 100644
--- a/arch/m68k/mm/hwtest.c
+++ b/arch/m68k/mm/hwtest.c
@@ -28,9 +28,11 @@
int hwreg_present( volatile void *regp )
{
int ret = 0;
+ unsigned long flags;
long save_sp, save_vbr;
long tmp_vectors[3];
+ local_irq_save(flags);
__asm__ __volatile__
( "movec %/vbr,%2\n\t"
"movel #Lberr1,%4@(8)\n\t"
@@ -46,6 +48,7 @@ int hwreg_present( volatile void *regp )
: "=&d" (ret), "=&r" (save_sp), "=&r" (save_vbr)
: "a" (regp), "a" (tmp_vectors)
);
+ local_irq_restore(flags);
return( ret );
}
@@ -58,9 +61,11 @@ EXPORT_SYMBOL(hwreg_present);
int hwreg_write( volatile void *regp, unsigned short val )
{
int ret;
+ unsigned long flags;
long save_sp, save_vbr;
long tmp_vectors[3];
+ local_irq_save(flags);
__asm__ __volatile__
( "movec %/vbr,%2\n\t"
"movel #Lberr2,%4@(8)\n\t"
@@ -78,6 +83,7 @@ int hwreg_write( volatile void *regp, unsigned short val )
: "=&d" (ret), "=&r" (save_sp), "=&r" (save_vbr)
: "a" (regp), "a" (tmp_vectors), "g" (val)
);
+ local_irq_restore(flags);
return( ret );
}