From 0d70262a2d60886da6fe5b1fc8bbcd76cbbc306d Mon Sep 17 00:00:00 2001 From: Russell King Date: Wed, 19 Jul 2017 23:09:58 +0100 Subject: ARM: kexec: fix failure to boot crash kernel When kexec was converted to DTB, the dtb address was passed between machine_kexec_prepare() and machine_kexec() using a static variable. This is bad news if you load a crash kernel followed by a normal kernel or vice versa - the last loaded kernel overwrites the dtb address. This can result in kexec failures, as (eg) we try to boot the crash kernel with the last loaded dtb. For example, with: the crash kernel fails to find the dtb. Avoid this by defining a kimage architecture structure, and store the address to be passed in r2 there, which will either be the ATAGs or the dtb blob. Fixes: 4cabd1d9625c ("ARM: 7539/1: kexec: scan for dtb magic in segments") Fixes: 42d720d1731a ("ARM: kexec: Make .text R/W in machine_kexec") Reported-by: Keerthy Tested-by: Keerthy Signed-off-by: Russell King --- arch/arm/include/asm/kexec.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'arch/arm/include') diff --git a/arch/arm/include/asm/kexec.h b/arch/arm/include/asm/kexec.h index 1869af6bac5c..25021b798a1e 100644 --- a/arch/arm/include/asm/kexec.h +++ b/arch/arm/include/asm/kexec.h @@ -19,6 +19,11 @@ #ifndef __ASSEMBLY__ +#define ARCH_HAS_KIMAGE_ARCH +struct kimage_arch { + u32 kernel_r2; +}; + /** * crash_setup_regs() - save registers for the panic kernel * @newregs: registers are saved here -- cgit v1.2.3 From ce184a0dee92a0a333236a26478e304dca29a3df Mon Sep 17 00:00:00 2001 From: Dave Martin Date: Fri, 30 Jun 2017 18:56:59 +0100 Subject: ARM: 8687/1: signal: Fix unparseable iwmmxt_sigframe in uc_regspace[] In kernels with CONFIG_IWMMXT=y running on non-iWMMXt hardware, the signal frame can be left partially uninitialised in such a way that userspace cannot parse uc_regspace[] safely. In particular, this means that the VFP registers cannot be located reliably in the signal frame when a multi_v7_defconfig kernel is run on the majority of platforms. The cause is that the uc_regspace[] is laid out statically based on the kernel config, but the decision of whether to save/restore the iWMMXt registers must be a runtime decision. To minimise breakage of software that may assume a fixed layout, this patch emits a dummy block of the same size as iwmmxt_sigframe, for non-iWMMXt threads. However, the magic and size of this block are now filled in to help parsers skip over it. A new DUMMY_MAGIC is defined for this purpose. It is probably legitimate (if non-portable) for userspace to manufacture its own sigframe for sigreturn, and there is no obvious reason why userspace should be required to insert a DUMMY_MAGIC block when running on non-iWMMXt hardware, when omitting it has worked just fine forever in other configurations. So in this case, sigreturn does not require this block to be present. Reported-by: Edmund Grimley-Evans Signed-off-by: Dave Martin Signed-off-by: Russell King --- arch/arm/include/asm/ucontext.h | 6 ++++ arch/arm/kernel/signal.c | 76 ++++++++++++++++++++++++++++++++--------- 2 files changed, 65 insertions(+), 17 deletions(-) (limited to 'arch/arm/include') diff --git a/arch/arm/include/asm/ucontext.h b/arch/arm/include/asm/ucontext.h index 14749aec94bf..921d8274855c 100644 --- a/arch/arm/include/asm/ucontext.h +++ b/arch/arm/include/asm/ucontext.h @@ -35,6 +35,12 @@ struct ucontext { * bytes, to prevent unpredictable padding in the signal frame. */ +/* + * Dummy padding block: if this magic is encountered, the block should + * be skipped using the corresponding size field. + */ +#define DUMMY_MAGIC 0xb0d9ed01 + #ifdef CONFIG_CRUNCH #define CRUNCH_MAGIC 0x5065cf03 #define CRUNCH_STORAGE_SIZE (CRUNCH_SIZE + 8) diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c index 8f064807d1ef..5814298ef0b7 100644 --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -40,8 +40,10 @@ static int preserve_crunch_context(struct crunch_sigframe __user *frame) return __copy_to_user(frame, kframe, sizeof(*frame)); } -static int restore_crunch_context(struct crunch_sigframe __user *frame) +static int restore_crunch_context(char __user **auxp) { + struct crunch_sigframe __user *frame = + (struct crunch_sigframe __user *)*auxp; char kbuf[sizeof(*frame) + 8]; struct crunch_sigframe *kframe; @@ -52,6 +54,7 @@ static int restore_crunch_context(struct crunch_sigframe __user *frame) if (kframe->magic != CRUNCH_MAGIC || kframe->size != CRUNCH_STORAGE_SIZE) return -1; + *auxp += CRUNCH_STORAGE_SIZE; crunch_task_restore(current_thread_info(), &kframe->storage); return 0; } @@ -63,17 +66,35 @@ static int preserve_iwmmxt_context(struct iwmmxt_sigframe __user *frame) { char kbuf[sizeof(*frame) + 8]; struct iwmmxt_sigframe *kframe; + int err = 0; /* the iWMMXt context must be 64 bit aligned */ kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7); - kframe->magic = IWMMXT_MAGIC; - kframe->size = IWMMXT_STORAGE_SIZE; - iwmmxt_task_copy(current_thread_info(), &kframe->storage); - return __copy_to_user(frame, kframe, sizeof(*frame)); + + if (test_thread_flag(TIF_USING_IWMMXT)) { + kframe->magic = IWMMXT_MAGIC; + kframe->size = IWMMXT_STORAGE_SIZE; + iwmmxt_task_copy(current_thread_info(), &kframe->storage); + + err = __copy_to_user(frame, kframe, sizeof(*frame)); + } else { + /* + * For bug-compatibility with older kernels, some space + * has to be reserved for iWMMXt even if it's not used. + * Set the magic and size appropriately so that properly + * written userspace can skip it reliably: + */ + __put_user_error(DUMMY_MAGIC, &frame->magic, err); + __put_user_error(IWMMXT_STORAGE_SIZE, &frame->size, err); + } + + return err; } -static int restore_iwmmxt_context(struct iwmmxt_sigframe __user *frame) +static int restore_iwmmxt_context(char __user **auxp) { + struct iwmmxt_sigframe __user *frame = + (struct iwmmxt_sigframe __user *)*auxp; char kbuf[sizeof(*frame) + 8]; struct iwmmxt_sigframe *kframe; @@ -81,10 +102,28 @@ static int restore_iwmmxt_context(struct iwmmxt_sigframe __user *frame) kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7); if (__copy_from_user(kframe, frame, sizeof(*frame))) return -1; - if (kframe->magic != IWMMXT_MAGIC || - kframe->size != IWMMXT_STORAGE_SIZE) + + /* + * For non-iWMMXt threads: a single iwmmxt_sigframe-sized dummy + * block is discarded for compatibility with setup_sigframe() if + * present, but we don't mandate its presence. If some other + * magic is here, it's not for us: + */ + if (!test_thread_flag(TIF_USING_IWMMXT) && + kframe->magic != DUMMY_MAGIC) + return 0; + + if (kframe->size != IWMMXT_STORAGE_SIZE) return -1; - iwmmxt_task_restore(current_thread_info(), &kframe->storage); + + if (test_thread_flag(TIF_USING_IWMMXT)) { + if (kframe->magic != IWMMXT_MAGIC) + return -1; + + iwmmxt_task_restore(current_thread_info(), &kframe->storage); + } + + *auxp += IWMMXT_STORAGE_SIZE; return 0; } @@ -107,8 +146,10 @@ static int preserve_vfp_context(struct vfp_sigframe __user *frame) return vfp_preserve_user_clear_hwstate(&frame->ufp, &frame->ufp_exc); } -static int restore_vfp_context(struct vfp_sigframe __user *frame) +static int restore_vfp_context(char __user **auxp) { + struct vfp_sigframe __user *frame = + (struct vfp_sigframe __user *)*auxp; unsigned long magic; unsigned long size; int err = 0; @@ -121,6 +162,7 @@ static int restore_vfp_context(struct vfp_sigframe __user *frame) if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE) return -EINVAL; + *auxp += size; return vfp_restore_user_hwstate(&frame->ufp, &frame->ufp_exc); } @@ -141,7 +183,7 @@ struct rt_sigframe { static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf) { - struct aux_sigframe __user *aux; + char __user *aux; sigset_t set; int err; @@ -169,18 +211,18 @@ static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf) err |= !valid_user_regs(regs); - aux = (struct aux_sigframe __user *) sf->uc.uc_regspace; + aux = (char __user *) sf->uc.uc_regspace; #ifdef CONFIG_CRUNCH if (err == 0) - err |= restore_crunch_context(&aux->crunch); + err |= restore_crunch_context(&aux); #endif #ifdef CONFIG_IWMMXT - if (err == 0 && test_thread_flag(TIF_USING_IWMMXT)) - err |= restore_iwmmxt_context(&aux->iwmmxt); + if (err == 0) + err |= restore_iwmmxt_context(&aux); #endif #ifdef CONFIG_VFP if (err == 0) - err |= restore_vfp_context(&aux->vfp); + err |= restore_vfp_context(&aux); #endif return err; @@ -286,7 +328,7 @@ setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set) err |= preserve_crunch_context(&aux->crunch); #endif #ifdef CONFIG_IWMMXT - if (err == 0 && test_thread_flag(TIF_USING_IWMMXT)) + if (err == 0) err |= preserve_iwmmxt_context(&aux->iwmmxt); #endif #ifdef CONFIG_VFP -- cgit v1.2.3