[PATCH 4.4 06/50] MIPS: Ensure bss section ends on a long-aligned address

[PATCH 4.4 06/50] MIPS: Ensure bss section ends on a long-aligned address

[Greg Kroah-Hartman]

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

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

From: Paul Burton <paul.burton@imgtec.com>


[ Upstream commit 3f00f4d8f083bc61005d0a1ef592b149f5c88bbd ]

When clearing the .bss section in kernel_entry we do so using LONG_S
instructions, and branch whilst the current write address doesn't equal
the end of the .bss section minus the size of a long integer. The .bss
section always begins at a long-aligned address and we always increment
the write pointer by the size of a long integer - we therefore rely upon
the .bss section ending at a long-aligned address. If this is not the
case then the long-aligned write address can never be equal to the
non-long-aligned end address & we will continue to increment past the
end of the .bss section, attempting to zero the rest of memory.

Despite this requirement that .bss end at a long-aligned address we pass
0 as the end alignment requirement to the BSS_SECTION macro and thus
don't guarantee any particular alignment, allowing us to hit the error
condition described above.

Fix this by instead passing 8 bytes as the end alignment argument to
the BSS_SECTION macro, ensuring that the end of the .bss section is
always at least long-aligned.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14526/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/mips/kernel/vmlinux.lds.S |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/mips/kernel/vmlinux.lds.S
+++ b/arch/mips/kernel/vmlinux.lds.S
@@ -159,7 +159,7 @@ SECTIONS
 	 * Force .bss to 64K alignment so that .bss..swapper_pg_dir
 	 * gets that alignment.	 .sbss should be empty, so there will be
 	 * no holes after __init_end. */
-	BSS_SECTION(0, 0x10000, 0)
+	BSS_SECTION(0, 0x10000, 8)
 
 	_end = . ;
 

[PATCH 4.4 07/50] MIPS: ralink: Fix incorrect assignment on ralink_soc

[Greg Kroah-Hartman]

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

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

From: Colin Ian King <colin.king@canonical.com>


[ Upstream commit 08d90c81b714482dceb5323d14f6617bcf55ee61 ]

ralink_soc sould be assigned to RT3883_SOC, replace incorrect
comparision with assignment.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Fixes: 418d29c87061 ("MIPS: ralink: Unify SoC id handling")
Cc: John Crispin <john@phrozen.org>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14903/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/mips/ralink/rt3883.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/mips/ralink/rt3883.c
+++ b/arch/mips/ralink/rt3883.c
@@ -144,5 +144,5 @@ void prom_soc_init(struct ralink_soc_inf
 
 	rt2880_pinmux_data = rt3883_pinmux_data;
 
-	ralink_soc == RT3883_SOC;
+	ralink_soc = RT3883_SOC;
 }

[PATCH 4.4 28/50] MIPS: Lantiq: Fix another request_mem_region() return code check

[Greg Kroah-Hartman]

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

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

From: Arnd Bergmann <arnd@arndb.de>


[ Upstream commit 98ea51cb0c8ce009d9da1fd7b48f0ff1d7a9bbb0 ]

Hauke already fixed a couple of them, but one instance remains
that checks for a negative integer when it should check
for a NULL pointer:

arch/mips/lantiq/xway/sysctrl.c: In function 'ltq_soc_init':
arch/mips/lantiq/xway/sysctrl.c:473:19: error: ordered comparison of pointer with integer zero [-Werror=extra]

Fixes: 6e807852676a ("MIPS: Lantiq: Fix check for return value of request_mem_region()")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: John Crispin <john@phrozen.org>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/15043/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/mips/lantiq/xway/sysctrl.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/mips/lantiq/xway/sysctrl.c
+++ b/arch/mips/lantiq/xway/sysctrl.c
@@ -469,8 +469,8 @@ void __init ltq_soc_init(void)
 			panic("Failed to load xbar nodes from devicetree");
 		if (of_address_to_resource(np_xbar, 0, &res_xbar))
 			panic("Failed to get xbar resources");
-		if (request_mem_region(res_xbar.start, resource_size(&res_xbar),
-			res_xbar.name) < 0)
+		if (!request_mem_region(res_xbar.start, resource_size(&res_xbar),
+			res_xbar.name))
 			panic("Failed to get xbar resources");
 
 		ltq_xbar_membase = ioremap_nocache(res_xbar.start,

[PATCH 4.4 36/50] MIPS: IRQ Stack: Unwind IRQ stack onto task stack

[Greg Kroah-Hartman]

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

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

From: Matt Redfearn <matt.redfearn@imgtec.com>


[ Upstream commit db8466c581cca1a08b505f1319c3ecd246f16fa8 ]

When the separate IRQ stack was introduced, stack unwinding only
proceeded as far as the top of the IRQ stack, leading to kernel
backtraces being less useful, lacking the trace of what was interrupted.

Fix this by providing a means for the kernel to unwind the IRQ stack
onto the interrupted task stack. The processor state is saved to the
kernel task stack on interrupt. The IRQ_STACK_START macro reserves an
unsigned long at the top of the IRQ stack where the interrupted task
stack pointer can be saved. After the active stack is switched to the
IRQ stack, save the interrupted tasks stack pointer to the reserved
location.

Fix the stack unwinding code to look for the frame being the top of the
IRQ stack and if so get the next frame from the saved location. The
existing test does not work with the separate stack since the ra is no
longer pointed at ret_from_{irq,exception}.

The test to stop unwinding the stack 32 bytes from the top of a stack
must be modified to allow unwinding to continue up to the location of
the saved task stack pointer when on the IRQ stack. The low / high marks
of the stack are set depending on whether the sp is on an irq stack or
not.

Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Cc: Masanari Iida <standby24x7@gmail.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jason A. Donenfeld <jason@zx2c4.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/15788/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/mips/include/asm/irq.h    |   15 ++++++++++
 arch/mips/kernel/asm-offsets.c |    1 
 arch/mips/kernel/genex.S       |    8 ++++-
 arch/mips/kernel/process.c     |   56 +++++++++++++++++++++++++++--------------
 4 files changed, 60 insertions(+), 20 deletions(-)

--- a/arch/mips/include/asm/irq.h
+++ b/arch/mips/include/asm/irq.h
@@ -18,9 +18,24 @@
 #include <irq.h>
 
 #define IRQ_STACK_SIZE			THREAD_SIZE
+#define IRQ_STACK_START			(IRQ_STACK_SIZE - sizeof(unsigned long))
 
 extern void *irq_stack[NR_CPUS];
 
+/*
+ * The highest address on the IRQ stack contains a dummy frame put down in
+ * genex.S (handle_int & except_vec_vi_handler) which is structured as follows:
+ *
+ *   top ------------
+ *       | task sp  | <- irq_stack[cpu] + IRQ_STACK_START
+ *       ------------
+ *       |          | <- First frame of IRQ context
+ *       ------------
+ *
+ * task sp holds a copy of the task stack pointer where the struct pt_regs
+ * from exception entry can be found.
+ */
+
 static inline bool on_irq_stack(int cpu, unsigned long sp)
 {
 	unsigned long low = (unsigned long)irq_stack[cpu];
--- a/arch/mips/kernel/asm-offsets.c
+++ b/arch/mips/kernel/asm-offsets.c
@@ -102,6 +102,7 @@ void output_thread_info_defines(void)
 	DEFINE(_THREAD_SIZE, THREAD_SIZE);
 	DEFINE(_THREAD_MASK, THREAD_MASK);
 	DEFINE(_IRQ_STACK_SIZE, IRQ_STACK_SIZE);
+	DEFINE(_IRQ_STACK_START, IRQ_STACK_START);
 	BLANK();
 }
 
--- a/arch/mips/kernel/genex.S
+++ b/arch/mips/kernel/genex.S
@@ -216,9 +216,11 @@ NESTED(handle_int, PT_SIZE, sp)
 	beq	t0, t1, 2f
 
 	/* Switch to IRQ stack */
-	li	t1, _IRQ_STACK_SIZE
+	li	t1, _IRQ_STACK_START
 	PTR_ADD sp, t0, t1
 
+	/* Save task's sp on IRQ stack so that unwinding can follow it */
+	LONG_S	s1, 0(sp)
 2:
 	jal	plat_irq_dispatch
 
@@ -326,9 +328,11 @@ NESTED(except_vec_vi_handler, 0, sp)
 	beq	t0, t1, 2f
 
 	/* Switch to IRQ stack */
-	li	t1, _IRQ_STACK_SIZE
+	li	t1, _IRQ_STACK_START
 	PTR_ADD sp, t0, t1
 
+	/* Save task's sp on IRQ stack so that unwinding can follow it */
+	LONG_S	s1, 0(sp)
 2:
 	jalr	v0
 
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -483,31 +483,52 @@ unsigned long notrace unwind_stack_by_ad
 					      unsigned long pc,
 					      unsigned long *ra)
 {
+	unsigned long low, high, irq_stack_high;
 	struct mips_frame_info info;
 	unsigned long size, ofs;
+	struct pt_regs *regs;
 	int leaf;
-	extern void ret_from_irq(void);
-	extern void ret_from_exception(void);
 
 	if (!stack_page)
 		return 0;
 
 	/*
-	 * If we reached the bottom of interrupt context,
-	 * return saved pc in pt_regs.
+	 * IRQ stacks start at IRQ_STACK_START
+	 * task stacks at THREAD_SIZE - 32
 	 */
-	if (pc == (unsigned long)ret_from_irq ||
-	    pc == (unsigned long)ret_from_exception) {
-		struct pt_regs *regs;
-		if (*sp >= stack_page &&
-		    *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
-			regs = (struct pt_regs *)*sp;
-			pc = regs->cp0_epc;
-			if (!user_mode(regs) && __kernel_text_address(pc)) {
-				*sp = regs->regs[29];
-				*ra = regs->regs[31];
-				return pc;
-			}
+	low = stack_page;
+	if (!preemptible() && on_irq_stack(raw_smp_processor_id(), *sp)) {
+		high = stack_page + IRQ_STACK_START;
+		irq_stack_high = high;
+	} else {
+		high = stack_page + THREAD_SIZE - 32;
+		irq_stack_high = 0;
+	}
+
+	/*
+	 * If we reached the top of the interrupt stack, start unwinding
+	 * the interrupted task stack.
+	 */
+	if (unlikely(*sp == irq_stack_high)) {
+		unsigned long task_sp = *(unsigned long *)*sp;
+
+		/*
+		 * Check that the pointer saved in the IRQ stack head points to
+		 * something within the stack of the current task
+		 */
+		if (!object_is_on_stack((void *)task_sp))
+			return 0;
+
+		/*
+		 * Follow pointer to tasks kernel stack frame where interrupted
+		 * state was saved.
+		 */
+		regs = (struct pt_regs *)task_sp;
+		pc = regs->cp0_epc;
+		if (!user_mode(regs) && __kernel_text_address(pc)) {
+			*sp = regs->regs[29];
+			*ra = regs->regs[31];
+			return pc;
 		}
 		return 0;
 	}
@@ -528,8 +549,7 @@ unsigned long notrace unwind_stack_by_ad
 	if (leaf < 0)
 		return 0;
 
-	if (*sp < stack_page ||
-	    *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
+	if (*sp < low || *sp + info.frame_size > high)
 		return 0;
 
 	if (leaf)

Re: [PATCH 4.4 36/50] MIPS: IRQ Stack: Unwind IRQ stack onto task stack

[Ben Hutchings]

On Fri, 2017-10-06 at 10:53 +0200, Greg Kroah-Hartman wrote:
> 4.4-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Matt Redfearn <matt.redfearn@imgtec.com>
> 
> 
> [ Upstream commit db8466c581cca1a08b505f1319c3ecd246f16fa8 ]
[...]

There was a follow-up to this which I suspect is also needed on the 4.4
and 4.9 branches: commit 5fdc66e04620 ("MIPS: Fix minimum alignment
requirement of IRQ stack").

Ben.

-- 
Ben Hutchings
Software Developer, Codethink Ltd.

Re: [PATCH 4.4 36/50] MIPS: IRQ Stack: Unwind IRQ stack onto task stack

[Matt Redfearn]

On 16/10/17 22:28, Ben Hutchings wrote:
> On Fri, 2017-10-06 at 10:53 +0200, Greg Kroah-Hartman wrote:
>> 4.4-stable review patch.  If anyone has any objections, please let me know.
>>
>> ------------------
>>
>> From: Matt Redfearn <matt.redfearn@imgtec.com>
>>
>>
>> [ Upstream commit db8466c581cca1a08b505f1319c3ecd246f16fa8 ]
> [...]
>
> There was a follow-up to this which I suspect is also needed on the 4.4
> and 4.9 branches: commit 5fdc66e04620 ("MIPS: Fix minimum alignment
> requirement of IRQ stack").
>
> Ben.
>
Hi Ben,

Yes you are correct, I missed tagging that one for stable. Please apply it.

Thanks,
Matt

Re: [PATCH 4.4 36/50] MIPS: IRQ Stack: Unwind IRQ stack onto task stack

[Matt Redfearn]

On 16/10/17 22:28, Ben Hutchings wrote:
> On Fri, 2017-10-06 at 10:53 +0200, Greg Kroah-Hartman wrote:
>> 4.4-stable review patch.  If anyone has any objections, please let me know.
>>
>> ------------------
>>
>> From: Matt Redfearn <matt.redfearn@imgtec.com>
>>
>>
>> [ Upstream commit db8466c581cca1a08b505f1319c3ecd246f16fa8 ]
> [...]
>
> There was a follow-up to this which I suspect is also needed on the 4.4
> and 4.9 branches: commit 5fdc66e04620 ("MIPS: Fix minimum alignment
> requirement of IRQ stack").
>
> Ben.
>
Hi Ben,

Yes you are correct, I missed tagging that one for stable. Please apply it.

Thanks,
Matt

Re: [PATCH 4.4 36/50] MIPS: IRQ Stack: Unwind IRQ stack onto task stack

[Greg Kroah-Hartman]

On Tue, Oct 17, 2017 at 08:18:23AM +0100, Matt Redfearn wrote:
> 
> 
> On 16/10/17 22:28, Ben Hutchings wrote:
> > On Fri, 2017-10-06 at 10:53 +0200, Greg Kroah-Hartman wrote:
> > > 4.4-stable review patch.  If anyone has any objections, please let me know.
> > > 
> > > ------------------
> > > 
> > > From: Matt Redfearn <matt.redfearn@imgtec.com>
> > > 
> > > 
> > > [ Upstream commit db8466c581cca1a08b505f1319c3ecd246f16fa8 ]
> > [...]
> > 
> > There was a follow-up to this which I suspect is also needed on the 4.4
> > and 4.9 branches: commit 5fdc66e04620 ("MIPS: Fix minimum alignment
> > requirement of IRQ stack").
> > 
> > Ben.
> > 
> Hi Ben,
> 
> Yes you are correct, I missed tagging that one for stable. Please apply it.

Thanks for letting me know, now queued up.

greg k-h