[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH] [RESEND] [v3] xen: remove pre-xen3 fallback handlers
The legacy hypercall handlers were originally added with a comment explaining that "copying the argument structures in HYPERVISOR_event_channel_op() and HYPERVISOR_physdev_op() into the local variable is sufficiently safe" and only made sure to not write past the end of the argument structure, the checks in linux/string.h disagree with that, when link-time optimizations are used: In function 'memcpy', inlined from 'pirq_query_unmask' at drivers/xen/fallback.c:53:2, inlined from '__startup_pirq' at drivers/xen/events/events_base.c:529:2, inlined from 'restore_pirqs' at drivers/xen/events/events_base.c:1439:3, inlined from 'xen_irq_resume' at drivers/xen/events/events_base.c:1581:2: include/linux/string.h:350:3: error: call to '__read_overflow2' declared with attribute error: detected read beyond size of object passed as 2nd parameter __read_overflow2(); ^ Further research turned out that only Xen 3.0.2 or earlier required the fallback at all, while all versions in use today don't need it. As far as I can tell, it is not even possible to run a mainline kernel on those old Xen releases, at the time when they were in use, only a patched kernel was supported anyway. Fixes: cf47a83fb06e ("xen/hypercall: fix hypercall fallback code for very old hypervisors") Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> Cc: Jan Beulich <JBeulich@xxxxxxxx> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> --- [v2] use a table lookup instead of a switch/case statement, after multiple suggestions. [v3] remove that file completely [resend] I just stumbled over this again, the last submission was a year ago, and it seems it never got merged --- arch/x86/include/asm/xen/hypercall.h | 13 +---- drivers/xen/Makefile | 1 - drivers/xen/fallback.c | 81 ---------------------------- 3 files changed, 2 insertions(+), 93 deletions(-) delete mode 100644 drivers/xen/fallback.c diff --git a/arch/x86/include/asm/xen/hypercall.h b/arch/x86/include/asm/xen/hypercall.h index ef05bea7010d..de6f0d59a24f 100644 --- a/arch/x86/include/asm/xen/hypercall.h +++ b/arch/x86/include/asm/xen/hypercall.h @@ -332,15 +332,11 @@ HYPERVISOR_update_va_mapping(unsigned long va, pte_t new_val, return _hypercall4(int, update_va_mapping, va, new_val.pte, new_val.pte >> 32, flags); } -extern int __must_check xen_event_channel_op_compat(int, void *); static inline int HYPERVISOR_event_channel_op(int cmd, void *arg) { - int rc = _hypercall2(int, event_channel_op, cmd, arg); - if (unlikely(rc == -ENOSYS)) - rc = xen_event_channel_op_compat(cmd, arg); - return rc; + return _hypercall2(int, event_channel_op, cmd, arg); } static inline int @@ -355,15 +351,10 @@ HYPERVISOR_console_io(int cmd, int count, char *str) return _hypercall3(int, console_io, cmd, count, str); } -extern int __must_check xen_physdev_op_compat(int, void *); - static inline int HYPERVISOR_physdev_op(int cmd, void *arg) { - int rc = _hypercall2(int, physdev_op, cmd, arg); - if (unlikely(rc == -ENOSYS)) - rc = xen_physdev_op_compat(cmd, arg); - return rc; + return _hypercall2(int, physdev_op, cmd, arg); } static inline int diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile index 5df6d21142f2..7124f9e749b4 100644 --- a/drivers/xen/Makefile +++ b/drivers/xen/Makefile @@ -1,6 +1,5 @@ # SPDX-License-Identifier: GPL-2.0 obj-$(CONFIG_HOTPLUG_CPU) += cpu_hotplug.o -obj-$(CONFIG_X86) += fallback.o obj-y += grant-table.o features.o balloon.o manage.o preempt.o time.o obj-y += mem-reservation.o obj-y += events/ diff --git a/drivers/xen/fallback.c b/drivers/xen/fallback.c deleted file mode 100644 index b04fb64c5a91..000000000000 --- a/drivers/xen/fallback.c +++ /dev/null @@ -1,81 +0,0 @@ -#include <linux/kernel.h> -#include <linux/string.h> -#include <linux/bug.h> -#include <linux/export.h> -#include <asm/hypervisor.h> -#include <asm/xen/hypercall.h> - -int xen_event_channel_op_compat(int cmd, void *arg) -{ - struct evtchn_op op; - int rc; - - op.cmd = cmd; - memcpy(&op.u, arg, sizeof(op.u)); - rc = _hypercall1(int, event_channel_op_compat, &op); - - switch (cmd) { - case EVTCHNOP_close: - case EVTCHNOP_send: - case EVTCHNOP_bind_vcpu: - case EVTCHNOP_unmask: - /* no output */ - break; - -#define COPY_BACK(eop) \ - case EVTCHNOP_##eop: \ - memcpy(arg, &op.u.eop, sizeof(op.u.eop)); \ - break - - COPY_BACK(bind_interdomain); - COPY_BACK(bind_virq); - COPY_BACK(bind_pirq); - COPY_BACK(status); - COPY_BACK(alloc_unbound); - COPY_BACK(bind_ipi); -#undef COPY_BACK - - default: - WARN_ON(rc != -ENOSYS); - break; - } - - return rc; -} -EXPORT_SYMBOL_GPL(xen_event_channel_op_compat); - -int xen_physdev_op_compat(int cmd, void *arg) -{ - struct physdev_op op; - int rc; - - op.cmd = cmd; - memcpy(&op.u, arg, sizeof(op.u)); - rc = _hypercall1(int, physdev_op_compat, &op); - - switch (cmd) { - case PHYSDEVOP_IRQ_UNMASK_NOTIFY: - case PHYSDEVOP_set_iopl: - case PHYSDEVOP_set_iobitmap: - case PHYSDEVOP_apic_write: - /* no output */ - break; - -#define COPY_BACK(pop, fld) \ - case PHYSDEVOP_##pop: \ - memcpy(arg, &op.u.fld, sizeof(op.u.fld)); \ - break - - COPY_BACK(irq_status_query, irq_status_query); - COPY_BACK(apic_read, apic_op); - COPY_BACK(ASSIGN_VECTOR, irq_op); -#undef COPY_BACK - - default: - WARN_ON(rc != -ENOSYS); - break; - } - - return rc; -} -EXPORT_SYMBOL_GPL(xen_physdev_op_compat); -- 2.20.0 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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