From 5a34133167dce36666ea054e30a561b7f4413b7f Mon Sep 17 00:00:00 2001 From: Huacai Chen Date: Thu, 16 Mar 2017 21:00:26 +0800 Subject: MIPS: Check TLB before handle_ri_rdhwr() for Loongson-3 Loongson-3's micro TLB (ITLB) is not strictly a subset of JTLB. That means: when a JTLB entry is replaced by hardware, there may be an old valid entry exists in ITLB. So, a TLB miss exception may occur while handle_ri_rdhwr() is running because it try to access EPC's content. However, handle_ri_rdhwr() doesn't clear EXL, which makes a TLB Refill exception be treated as a TLB Invalid exception and tlbp may fail. In this case, if FTLB (which is usually set-associative instead of set- associative) is enabled, a tlbp failure will cause an invalid tlbwi, which will hang the whole system. This patch rename handle_ri_rdhwr_vivt to handle_ri_rdhwr_tlbp and use it for Loongson-3. It try to solve the same problem described as below, but more straightforwards. https://patchwork.linux-mips.org/patch/12591/ I think Loongson-2 has the same problem, but it has no FTLB, so we just keep it as is. Signed-off-by: Huacai Chen Cc: Rui Wang Cc: John Crispin Cc: Steven J . Hill Cc: Fuxin Zhang Cc: Zhangjin Wu Cc: Huacai Chen Cc: linux-mips@linux-mips.org Cc: stable@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/15753/ Signed-off-by: Ralf Baechle --- arch/mips/kernel/genex.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/mips/kernel/genex.S') diff --git a/arch/mips/kernel/genex.S b/arch/mips/kernel/genex.S index 7ec9612cb007..2ac6c2625c13 100644 --- a/arch/mips/kernel/genex.S +++ b/arch/mips/kernel/genex.S @@ -519,7 +519,7 @@ NESTED(nmi_handler, PT_SIZE, sp) BUILD_HANDLER reserved reserved sti verbose /* others */ .align 5 - LEAF(handle_ri_rdhwr_vivt) + LEAF(handle_ri_rdhwr_tlbp) .set push .set noat .set noreorder @@ -538,7 +538,7 @@ NESTED(nmi_handler, PT_SIZE, sp) .set pop bltz k1, handle_ri /* slow path */ /* fall thru */ - END(handle_ri_rdhwr_vivt) + END(handle_ri_rdhwr_tlbp) LEAF(handle_ri_rdhwr) .set push -- cgit v1.2.3 From db8466c581cca1a08b505f1319c3ecd246f16fa8 Mon Sep 17 00:00:00 2001 From: Matt Redfearn Date: Tue, 21 Mar 2017 14:52:25 +0000 Subject: MIPS: IRQ Stack: Unwind IRQ stack onto task stack 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 Cc: Paolo Bonzini Cc: Marcin Nowakowski Cc: Masanari Iida Cc: Chris Metcalf Cc: James Hogan Cc: Paul Burton Cc: Ingo Molnar Cc: Jason A. Donenfeld Cc: Andrew Morton 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 --- arch/mips/kernel/genex.S | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'arch/mips/kernel/genex.S') diff --git a/arch/mips/kernel/genex.S b/arch/mips/kernel/genex.S index 2ac6c2625c13..ae810da4d499 100644 --- a/arch/mips/kernel/genex.S +++ b/arch/mips/kernel/genex.S @@ -215,9 +215,11 @@ 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 @@ -325,9 +327,11 @@ 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 -- cgit v1.2.3