From 3d13f313ce4c34c524ccc37986fe77172f601ff3 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 11 Aug 2020 18:33:47 -0700 Subject: uaccess: add force_uaccess_{begin,end} helpers Add helpers to wrap the get_fs/set_fs magic for undoing any damange done by set_fs(KERNEL_DS). There is no real functional benefit, but this documents the intent of these calls better, and will allow stubbing the functions out easily for kernels builds that do not allow address space overrides in the future. [hch@lst.de: drop two incorrect hunks, fix a commit log typo] Link: http://lkml.kernel.org/r/20200714105505.935079-6-hch@lst.de Signed-off-by: Christoph Hellwig Signed-off-by: Andrew Morton Acked-by: Linus Torvalds Acked-by: Mark Rutland Acked-by: Greentime Hu Acked-by: Geert Uytterhoeven Cc: Nick Hu Cc: Vincent Chen Cc: Paul Walmsley Cc: Palmer Dabbelt Link: http://lkml.kernel.org/r/20200710135706.537715-6-hch@lst.de Signed-off-by: Linus Torvalds --- arch/arm64/kernel/sdei.c | 2 +- arch/m68k/include/asm/tlbflush.h | 6 +++--- arch/mips/kernel/unaligned.c | 27 +++++++++++++-------------- arch/nds32/mm/alignment.c | 7 +++---- arch/sh/kernel/traps_32.c | 12 +++++------- 5 files changed, 25 insertions(+), 29 deletions(-) (limited to 'arch') diff --git a/arch/arm64/kernel/sdei.c b/arch/arm64/kernel/sdei.c index dab88260b137..7689f2031c0c 100644 --- a/arch/arm64/kernel/sdei.c +++ b/arch/arm64/kernel/sdei.c @@ -180,7 +180,7 @@ static __kprobes unsigned long _sdei_handler(struct pt_regs *regs, /* * We didn't take an exception to get here, set PAN. UAO will be cleared - * by sdei_event_handler()s set_fs(USER_DS) call. + * by sdei_event_handler()s force_uaccess_begin() call. */ __uaccess_enable_hw_pan(); diff --git a/arch/m68k/include/asm/tlbflush.h b/arch/m68k/include/asm/tlbflush.h index 191e75a6bb24..5337bc2c262f 100644 --- a/arch/m68k/include/asm/tlbflush.h +++ b/arch/m68k/include/asm/tlbflush.h @@ -85,10 +85,10 @@ static inline void flush_tlb_mm(struct mm_struct *mm) static inline void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr) { if (vma->vm_mm == current->active_mm) { - mm_segment_t old_fs = get_fs(); - set_fs(USER_DS); + mm_segment_t old_fs = force_uaccess_begin(); + __flush_tlb_one(addr); - set_fs(old_fs); + force_uaccess_end(old_fs); } } diff --git a/arch/mips/kernel/unaligned.c b/arch/mips/kernel/unaligned.c index 0adce604fa44..126a5f3f4e4c 100644 --- a/arch/mips/kernel/unaligned.c +++ b/arch/mips/kernel/unaligned.c @@ -191,17 +191,16 @@ static void emulate_load_store_insn(struct pt_regs *regs, * memory, so we need to "switch" the address limit to * user space, so that address check can work properly. */ - seg = get_fs(); - set_fs(USER_DS); + seg = force_uaccess_begin(); switch (insn.spec3_format.func) { case lhe_op: if (!access_ok(addr, 2)) { - set_fs(seg); + force_uaccess_end(seg); goto sigbus; } LoadHWE(addr, value, res); if (res) { - set_fs(seg); + force_uaccess_end(seg); goto fault; } compute_return_epc(regs); @@ -209,12 +208,12 @@ static void emulate_load_store_insn(struct pt_regs *regs, break; case lwe_op: if (!access_ok(addr, 4)) { - set_fs(seg); + force_uaccess_end(seg); goto sigbus; } LoadWE(addr, value, res); if (res) { - set_fs(seg); + force_uaccess_end(seg); goto fault; } compute_return_epc(regs); @@ -222,12 +221,12 @@ static void emulate_load_store_insn(struct pt_regs *regs, break; case lhue_op: if (!access_ok(addr, 2)) { - set_fs(seg); + force_uaccess_end(seg); goto sigbus; } LoadHWUE(addr, value, res); if (res) { - set_fs(seg); + force_uaccess_end(seg); goto fault; } compute_return_epc(regs); @@ -235,35 +234,35 @@ static void emulate_load_store_insn(struct pt_regs *regs, break; case she_op: if (!access_ok(addr, 2)) { - set_fs(seg); + force_uaccess_end(seg); goto sigbus; } compute_return_epc(regs); value = regs->regs[insn.spec3_format.rt]; StoreHWE(addr, value, res); if (res) { - set_fs(seg); + force_uaccess_end(seg); goto fault; } break; case swe_op: if (!access_ok(addr, 4)) { - set_fs(seg); + force_uaccess_end(seg); goto sigbus; } compute_return_epc(regs); value = regs->regs[insn.spec3_format.rt]; StoreWE(addr, value, res); if (res) { - set_fs(seg); + force_uaccess_end(seg); goto fault; } break; default: - set_fs(seg); + force_uaccess_end(seg); goto sigill; } - set_fs(seg); + force_uaccess_end(seg); } #endif break; diff --git a/arch/nds32/mm/alignment.c b/arch/nds32/mm/alignment.c index c8b9061a2ee3..1eb7ded6992b 100644 --- a/arch/nds32/mm/alignment.c +++ b/arch/nds32/mm/alignment.c @@ -512,7 +512,7 @@ int do_unaligned_access(unsigned long addr, struct pt_regs *regs) { unsigned long inst; int ret = -EFAULT; - mm_segment_t seg = get_fs(); + mm_segment_t seg; inst = get_inst(regs->ipc); @@ -520,13 +520,12 @@ int do_unaligned_access(unsigned long addr, struct pt_regs *regs) "Faulting addr: 0x%08lx, pc: 0x%08lx [inst: 0x%08lx ]\n", addr, regs->ipc, inst); - set_fs(USER_DS); - + seg = force_uaccess_begin(); if (inst & NDS32_16BIT_INSTRUCTION) ret = do_16((inst >> 16) & 0xffff, regs); else ret = do_32(inst, regs); - set_fs(seg); + force_uaccess_end(seg); return ret; } diff --git a/arch/sh/kernel/traps_32.c b/arch/sh/kernel/traps_32.c index 058c6181bb30..b62ad0ba2395 100644 --- a/arch/sh/kernel/traps_32.c +++ b/arch/sh/kernel/traps_32.c @@ -482,8 +482,6 @@ asmlinkage void do_address_error(struct pt_regs *regs, error_code = lookup_exception_vector(); #endif - oldfs = get_fs(); - if (user_mode(regs)) { int si_code = BUS_ADRERR; unsigned int user_action; @@ -491,13 +489,13 @@ asmlinkage void do_address_error(struct pt_regs *regs, local_irq_enable(); inc_unaligned_user_access(); - set_fs(USER_DS); + oldfs = force_uaccess_begin(); if (copy_from_user(&instruction, (insn_size_t *)(regs->pc & ~1), sizeof(instruction))) { - set_fs(oldfs); + force_uaccess_end(oldfs); goto uspace_segv; } - set_fs(oldfs); + force_uaccess_end(oldfs); /* shout about userspace fixups */ unaligned_fixups_notify(current, instruction, regs); @@ -520,11 +518,11 @@ fixup: goto uspace_segv; } - set_fs(USER_DS); + oldfs = force_uaccess_begin(); tmp = handle_unaligned_access(instruction, regs, &user_mem_access, 0, address); - set_fs(oldfs); + force_uaccess_end(oldfs); if (tmp == 0) return; /* sorted */ -- cgit v1.2.3