From 560b423dd9af4272a1f3685c2d6b073fdc4af7c7 Mon Sep 17 00:00:00 2001 From: Stafford Horne Date: Mon, 18 Jun 2018 06:52:58 +0900 Subject: openrisc: Call destructor during __pte_free_tlb This fixes an issue uncovered when a recent change to add the "page table" flag was merged. During bootup we see many errors like the following: BUG: Bad page state in process mkdir pfn:00bae page:c1ff15c0 count:0 mapcount:-1024 mapping:00000000 index:0x0 flags: 0x0() raw: 00000000 00000000 00000000 fffffbff 00000000 00000100 00000200 00000000 page dumped because: nonzero mapcount Modules linked in: CPU: 0 PID: 46 Comm: mkdir Tainted: G B 4.17.0-simple-smp-07461-g1d40a5ea01d5-dirty #993 Call trace: [<(ptrval)>] show_stack+0x44/0x54 [<(ptrval)>] dump_stack+0xb0/0xe8 [<(ptrval)>] bad_page+0x138/0x174 [<(ptrval)>] ? cpumask_next+0x24/0x34 [<(ptrval)>] free_pages_check_bad+0x6c/0xd0 [<(ptrval)>] free_pcppages_bulk+0x174/0x42c [<(ptrval)>] free_unref_page_commit.isra.17+0xb8/0xc8 [<(ptrval)>] free_unref_page_list+0x10c/0x190 [<(ptrval)>] ? set_reset_devices+0x0/0x2c [<(ptrval)>] release_pages+0x3a0/0x414 [<(ptrval)>] tlb_flush_mmu_free+0x5c/0x90 [<(ptrval)>] tlb_flush_mmu+0x90/0xa4 [<(ptrval)>] arch_tlb_finish_mmu+0x50/0x94 [<(ptrval)>] tlb_finish_mmu+0x30/0x64 [<(ptrval)>] exit_mmap+0x110/0x1e0 [<(ptrval)>] mmput+0x50/0xf0 [<(ptrval)>] do_exit+0x274/0xa94 [<(ptrval)>] do_group_exit+0x50/0x110 [<(ptrval)>] __wake_up_parent+0x0/0x38 [<(ptrval)>] _syscall_return+0x0/0x4 During the __pte_free_tlb path openrisc fails to call the page destructor which would clear the new bits that were introduced. To fix this we are calling the destructor. It seem openrisc was the only architecture missing this, all other architectures either call the destructor like we are doing here or use pte_free. Note: failing to call the destructor was also messing up the zone stats (and will be cause other problems if you were using SPLIT_PTE_PTLOCKS, which we are not yet). Fixes: 1d40a5ea01d53 ("mm: mark pages in use for page tables") Acked-by: Matthew Wilcox Signed-off-by: Stafford Horne --- arch/openrisc/include/asm/pgalloc.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'arch/openrisc') diff --git a/arch/openrisc/include/asm/pgalloc.h b/arch/openrisc/include/asm/pgalloc.h index 3e1a46615120..8999b9226512 100644 --- a/arch/openrisc/include/asm/pgalloc.h +++ b/arch/openrisc/include/asm/pgalloc.h @@ -98,8 +98,12 @@ static inline void pte_free(struct mm_struct *mm, struct page *pte) __free_page(pte); } +#define __pte_free_tlb(tlb, pte, addr) \ +do { \ + pgtable_page_dtor(pte); \ + tlb_remove_page((tlb), (pte)); \ +} while (0) -#define __pte_free_tlb(tlb, pte, addr) tlb_remove_page((tlb), (pte)) #define pmd_pgtable(pmd) pmd_page(pmd) #define check_pgt_cache() do { } while (0) -- cgit v1.2.3 From ae15a41a641449f536578b0d9ec0e4ade130deb5 Mon Sep 17 00:00:00 2001 From: Stafford Horne Date: Sun, 1 Jul 2018 14:17:36 +0900 Subject: openrisc: entry: Fix delay slot exception detection Originally in patch e6d20c55a4 ("openrisc: entry: Fix delay slot detection") I fixed delay slot detection, but only for QEMU. We missed that hardware delay slot detection using delay slot exception flag (DSX) was still broken. This was because QEMU set the DSX flag in both pre-exception supervision register (ESR) and supervision register (SR) register, but on real hardware the DSX flag is only set on the SR register during exceptions. Fix this by carrying the DSX flag into the SR register during exception. We also update the DSX flag read locations to read the value from the SR register not the pt_regs SR register which represents ESR. The ESR should never have the DSX flag set. In the process I updated/removed a few comments to match the current state. Including removing a comment saying that the DSX detection logic was inefficient and needed to be rewritten. I have tested this on QEMU with a patch ensuring it matches the hardware specification. Link: https://lists.gnu.org/archive/html/qemu-devel/2018-07/msg00000.html Fixes: e6d20c55a4 ("openrisc: entry: Fix delay slot detection") Signed-off-by: Stafford Horne --- arch/openrisc/kernel/entry.S | 8 +------- arch/openrisc/kernel/head.S | 9 ++++++--- arch/openrisc/kernel/traps.c | 2 +- 3 files changed, 8 insertions(+), 11 deletions(-) (limited to 'arch/openrisc') diff --git a/arch/openrisc/kernel/entry.S b/arch/openrisc/kernel/entry.S index 690d55272ba6..0c826ad6e994 100644 --- a/arch/openrisc/kernel/entry.S +++ b/arch/openrisc/kernel/entry.S @@ -277,12 +277,6 @@ EXCEPTION_ENTRY(_data_page_fault_handler) l.addi r3,r1,0 // pt_regs /* r4 set be EXCEPTION_HANDLE */ // effective address of fault - /* - * __PHX__: TODO - * - * all this can be written much simpler. look at - * DTLB miss handler in the CONFIG_GUARD_PROTECTED_CORE part - */ #ifdef CONFIG_OPENRISC_NO_SPR_SR_DSX l.lwz r6,PT_PC(r3) // address of an offending insn l.lwz r6,0(r6) // instruction that caused pf @@ -314,7 +308,7 @@ EXCEPTION_ENTRY(_data_page_fault_handler) #else - l.lwz r6,PT_SR(r3) // SR + l.mfspr r6,r0,SPR_SR // SR l.andi r6,r6,SPR_SR_DSX // check for delay slot exception l.sfne r6,r0 // exception happened in delay slot l.bnf 7f diff --git a/arch/openrisc/kernel/head.S b/arch/openrisc/kernel/head.S index fb02b2a1d6f2..9fc6b60140f0 100644 --- a/arch/openrisc/kernel/head.S +++ b/arch/openrisc/kernel/head.S @@ -210,8 +210,7 @@ * r4 - EEAR exception EA * r10 - current pointing to current_thread_info struct * r12 - syscall 0, since we didn't come from syscall - * r13 - temp it actually contains new SR, not needed anymore - * r31 - handler address of the handler we'll jump to + * r30 - handler address of the handler we'll jump to * * handler has to save remaining registers to the exception * ksp frame *before* tainting them! @@ -244,6 +243,7 @@ /* r1 is KSP, r30 is __pa(KSP) */ ;\ tophys (r30,r1) ;\ l.sw PT_GPR12(r30),r12 ;\ + /* r4 use for tmp before EA */ ;\ l.mfspr r12,r0,SPR_EPCR_BASE ;\ l.sw PT_PC(r30),r12 ;\ l.mfspr r12,r0,SPR_ESR_BASE ;\ @@ -263,7 +263,10 @@ /* r12 == 1 if we come from syscall */ ;\ CLEAR_GPR(r12) ;\ /* ----- turn on MMU ----- */ ;\ - l.ori r30,r0,(EXCEPTION_SR) ;\ + /* Carry DSX into exception SR */ ;\ + l.mfspr r30,r0,SPR_SR ;\ + l.andi r30,r30,SPR_SR_DSX ;\ + l.ori r30,r30,(EXCEPTION_SR) ;\ l.mtspr r0,r30,SPR_ESR_BASE ;\ /* r30: EA address of handler */ ;\ LOAD_SYMBOL_2_GPR(r30,handler) ;\ diff --git a/arch/openrisc/kernel/traps.c b/arch/openrisc/kernel/traps.c index fac246e6f37a..d8981cbb852a 100644 --- a/arch/openrisc/kernel/traps.c +++ b/arch/openrisc/kernel/traps.c @@ -300,7 +300,7 @@ static inline int in_delay_slot(struct pt_regs *regs) return 0; } #else - return regs->sr & SPR_SR_DSX; + return mfspr(SPR_SR) & SPR_SR_DSX; #endif } -- cgit v1.2.3