From e0d407564b532d978b03ceccebd224a05d02f111 Mon Sep 17 00:00:00 2001 From: Russell King Date: Sat, 3 Aug 2013 10:30:05 +0100 Subject: [PATCH 1/2] ARM: fix a cockup in 48be69a02 (ARM: move signal handlers into a vdso-like page) Unfortunately, I never committed the fix to a nasty oops which can occur as a result of that commit: ------------[ cut here ]------------ kernel BUG at /home/olof/work/batch/include/linux/mm.h:414! Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM Modules linked in: CPU: 0 PID: 490 Comm: killall5 Not tainted 3.11.0-rc3-00288-gabe0308 #53 task: e90acac0 ti: e9be8000 task.ti: e9be8000 PC is at special_mapping_fault+0xa4/0xc4 LR is at __do_fault+0x68/0x48c This doesn't show up unless you do quite a bit of testing; a simple boot test does not do this, so all my nightly tests were passing fine. The reason for this is that install_special_mapping() expects the page array to stick around, and as this was only inserting one page which was stored on the kernel stack, that's why this was blowing up. Reported-by: Olof Johansson Tested-by: Olof Johansson Signed-off-by: Russell King --- arch/arm/kernel/process.c | 9 +++++---- arch/arm/kernel/signal.c | 41 ++++++++++++++++++--------------------- 2 files changed, 24 insertions(+), 26 deletions(-) diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c index 1e6c33d01c05..d03b5bd889c5 100644 --- a/arch/arm/kernel/process.c +++ b/arch/arm/kernel/process.c @@ -471,17 +471,18 @@ const char *arch_vma_name(struct vm_area_struct *vma) "[sigpage]" : NULL; } +static struct page *signal_page; extern struct page *get_signal_page(void); int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) { struct mm_struct *mm = current->mm; - struct page *page; unsigned long addr; int ret; - page = get_signal_page(); - if (!page) + if (!signal_page) + signal_page = get_signal_page(); + if (!signal_page) return -ENOMEM; down_write(&mm->mmap_sem); @@ -493,7 +494,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) ret = install_special_mapping(mm, addr, PAGE_SIZE, VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC, - &page); + &signal_page); if (ret == 0) mm->context.sigpage = addr; diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c index 0f17e06d51e6..39e7105a9b70 100644 --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -614,35 +614,32 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall) return 0; } -static struct page *signal_page; - struct page *get_signal_page(void) { - if (!signal_page) { - unsigned long ptr; - unsigned offset; - void *addr; + unsigned long ptr; + unsigned offset; + struct page *page; + void *addr; - signal_page = alloc_pages(GFP_KERNEL, 0); + page = alloc_pages(GFP_KERNEL, 0); - if (!signal_page) - return NULL; + if (!page) + return NULL; - addr = page_address(signal_page); + addr = page_address(page); - /* Give the signal return code some randomness */ - offset = 0x200 + (get_random_int() & 0x7fc); - signal_return_offset = offset; + /* Give the signal return code some randomness */ + offset = 0x200 + (get_random_int() & 0x7fc); + signal_return_offset = offset; - /* - * Copy signal return handlers into the vector page, and - * set sigreturn to be a pointer to these. - */ - memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes)); + /* + * Copy signal return handlers into the vector page, and + * set sigreturn to be a pointer to these. + */ + memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes)); - ptr = (unsigned long)addr + offset; - flush_icache_range(ptr, ptr + sizeof(sigreturn_codes)); - } + ptr = (unsigned long)addr + offset; + flush_icache_range(ptr, ptr + sizeof(sigreturn_codes)); - return signal_page; + return page; } From 8c0cc8a5d90bc7373a7a9e7f7a40eb41f51e03fc Mon Sep 17 00:00:00 2001 From: Russell King Date: Sat, 3 Aug 2013 10:39:51 +0100 Subject: [PATCH 2/2] ARM: fix nommu builds with 48be69a02 (ARM: move signal handlers into a vdso-like page) Olof reports that noMMU builds error out with: arch/arm/kernel/signal.c: In function 'setup_return': arch/arm/kernel/signal.c:413:25: error: 'mm_context_t' has no member named 'sigpage' This shows one of the evilnesses of IS_ENABLED(). Get rid of it here and replace it with #ifdef's - and as no noMMU platform can make use of sigpage, depend on CONIFG_MMU not CONFIG_ARM_MPU. Reported-by: Olof Johansson Signed-off-by: Russell King --- arch/arm/include/asm/elf.h | 2 ++ arch/arm/kernel/signal.c | 7 +++++-- 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/arm/include/asm/elf.h b/arch/arm/include/asm/elf.h index 9c9b30717fda..56211f2084ef 100644 --- a/arch/arm/include/asm/elf.h +++ b/arch/arm/include/asm/elf.h @@ -130,8 +130,10 @@ struct mm_struct; extern unsigned long arch_randomize_brk(struct mm_struct *mm); #define arch_randomize_brk arch_randomize_brk +#ifdef CONFIG_MMU #define ARCH_HAS_SETUP_ADDITIONAL_PAGES 1 struct linux_binprm; int arch_setup_additional_pages(struct linux_binprm *, int); +#endif #endif diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c index 39e7105a9b70..ab3304225272 100644 --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -402,7 +402,8 @@ setup_return(struct pt_regs *regs, struct ksignal *ksig, __put_user(sigreturn_codes[idx+1], rc+1)) return 1; - if ((cpsr & MODE32_BIT) && !IS_ENABLED(CONFIG_ARM_MPU)) { +#ifdef CONFIG_MMU + if (cpsr & MODE32_BIT) { struct mm_struct *mm = current->mm; /* @@ -412,7 +413,9 @@ setup_return(struct pt_regs *regs, struct ksignal *ksig, */ retcode = mm->context.sigpage + signal_return_offset + (idx << 2) + thumb; - } else { + } else +#endif + { /* * Ensure that the instruction cache sees * the return code written onto the stack.