[PATCH 3.10 11/46] recordmcount/MIPS: Fix possible incorrect mcount_loc table entries in modules

[PATCH 3.10 11/46] recordmcount/MIPS: Fix possible incorrect mcount_loc table entries in modules

[Greg Kroah-Hartman]

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

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

From: Alex Smith <alex.smith@imgtec.com>

commit 91ad11d7cc6f4472ebf177a6252fbf0fd100d798 upstream.

On MIPS calls to _mcount in modules generate 2 instructions to load
the _mcount address (and therefore 2 relocations). The mcount_loc
table should only reference the first of these, so the second is
filtered out by checking the relocation offset and ignoring ones that
immediately follow the previous one seen.

However if a module has an _mcount call at offset 0, the second
relocation would not be filtered out due to old_r_offset == 0
being taken to mean that the current relocation is the first one
seen, and both would end up in the mcount_loc table.

This results in ftrace_make_nop() patching both (adjacent)
instructions to branches over the _mcount call sequence like so:

  0xffffffffc08a8000:  04 00 00 10     b       0xffffffffc08a8014
  0xffffffffc08a8004:  04 00 00 10     b       0xffffffffc08a8018
  0xffffffffc08a8008:  2d 08 e0 03     move    at,ra
  ...

The second branch is in the delay slot of the first, which is
defined to be unpredictable - on the platform on which this bug was
encountered, it triggers a reserved instruction exception.

Fix by initializing old_r_offset to ~0 and using that instead of 0
to determine whether the current relocation is the first seen.

Signed-off-by: Alex Smith <alex.smith@imgtec.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7098/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 scripts/recordmcount.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/scripts/recordmcount.h
+++ b/scripts/recordmcount.h
@@ -163,11 +163,11 @@ static int mcount_adjust = 0;
 
 static int MIPS_is_fake_mcount(Elf_Rel const *rp)
 {
-	static Elf_Addr old_r_offset;
+	static Elf_Addr old_r_offset = ~(Elf_Addr)0;
 	Elf_Addr current_r_offset = _w(rp->r_offset);
 	int is_fake;
 
-	is_fake = old_r_offset &&
+	is_fake = (old_r_offset != ~(Elf_Addr)0) &&
 		(current_r_offset - old_r_offset == MIPS_FAKEMCOUNT_OFFSET);
 	old_r_offset = current_r_offset;
 

[PATCH 3.10 12/46] MIPS: MSC: Prevent out-of-bounds writes to MIPS SC ioremapd region

[Greg Kroah-Hartman]

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

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

From: Markos Chandras <markos.chandras@imgtec.com>

commit ab6c15bc6620ebe220970cc040b29bcb2757f373 upstream.

Previously, the lower limit for the MIPS SC initialization loop was
set incorrectly allowing one extra loop leading to writes
beyond the MSC ioremap'd space. More precisely, the value of the 'imp'
in the last loop increased beyond the msc_irqmap_t boundaries and
as a result of which, the 'n' variable was loaded with an incorrect
value. This value was used later on to calculate the offset in the
MSC01_IC_SUP which led to random crashes like the following one:

CPU 0 Unable to handle kernel paging request at virtual address e75c0200,
epc == 8058dba4, ra == 8058db90
[...]
Call Trace:
[<8058dba4>] init_msc_irqs+0x104/0x154
[<8058b5bc>] arch_init_irq+0xd8/0x154
[<805897b0>] start_kernel+0x220/0x36c

Kernel panic - not syncing: Attempted to kill the idle task!

This patch fixes the problem

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7118/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/mips/kernel/irq-msc01.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/mips/kernel/irq-msc01.c
+++ b/arch/mips/kernel/irq-msc01.c
@@ -131,7 +131,7 @@ void __init init_msc_irqs(unsigned long
 
 	board_bind_eic_interrupt = &msc_bind_eic_interrupt;
 
-	for (; nirq >= 0; nirq--, imp++) {
+	for (; nirq > 0; nirq--, imp++) {
 		int n = imp->im_irq;
 
 		switch (imp->im_type) {

[PATCH 3.10 35/46] MIPS: KVM: Remove redundant NULL checks before kfree()

[Greg Kroah-Hartman]

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

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

From: James Hogan <james.hogan@imgtec.com>

commit c6c0a6637f9da54f9472144d44f71cf847f92e20 upstream.

The kfree() function already NULL checks the parameter so remove the
redundant NULL checks before kfree() calls in arch/mips/kvm/.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: kvm@vger.kernel.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: Sanjay Lal <sanjayl@kymasys.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/mips/kvm/kvm_mips.c |   12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

--- a/arch/mips/kvm/kvm_mips.c
+++ b/arch/mips/kvm/kvm_mips.c
@@ -149,9 +149,7 @@ void kvm_mips_free_vcpus(struct kvm *kvm
 		if (kvm->arch.guest_pmap[i] != KVM_INVALID_PAGE)
 			kvm_mips_release_pfn_clean(kvm->arch.guest_pmap[i]);
 	}
-
-	if (kvm->arch.guest_pmap)
-		kfree(kvm->arch.guest_pmap);
+	kfree(kvm->arch.guest_pmap);
 
 	kvm_for_each_vcpu(i, vcpu, kvm) {
 		kvm_arch_vcpu_free(vcpu);
@@ -384,12 +382,8 @@ void kvm_arch_vcpu_free(struct kvm_vcpu
 
 	kvm_mips_dump_stats(vcpu);
 
-	if (vcpu->arch.guest_ebase)
-		kfree(vcpu->arch.guest_ebase);
-
-	if (vcpu->arch.kseg0_commpage)
-		kfree(vcpu->arch.kseg0_commpage);
-
+	kfree(vcpu->arch.guest_ebase);
+	kfree(vcpu->arch.kseg0_commpage);
 }
 
 void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)