perf: Handle compat ioctl (b3f20785) · Commits · 戴 / test

When running a 32-bit userspace on a 64-bit kernel (eg. i386 application on x86_64 kernel or 32-bit arm userspace on arm64 kernel) some of the perf ioctls must be treated with special care, as they have a pointer size encoded in the command. For example, PERF_EVENT_IOC_ID in 32-bit world will be encoded as 0x80042407, but 64-bit kernel will expect 0x80082407. In result the ioctl will fail returning -ENOTTY. This patch solves the problem by adding code fixing up the size as compat_ioctl file operation. Reported-by:

Drew Richardson <drew.richardson@arm.com> Signed-off-by:

Pawel Moll <pawel.moll@arm.com> Signed-off-by:

Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Link: http://lkml.kernel.org/r/1402671812-9078-1-git-send-email-pawel.moll@arm.com Signed-off-by:

Ingo Molnar <mingo@kernel.org>

kernel/events/core.c

+22 −1

Original line number	Diff line number	Diff line
		@@ -41,6 +41,7 @@
		#include <linux/cgroup.h>
		#include <linux/module.h>
		#include <linux/mman.h>
		#include <linux/compat.h>

		#include "internal.h"

		@@ -3717,6 +3718,26 @@ static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
		return 0;
		}

		#ifdef CONFIG_COMPAT
		static long perf_compat_ioctl(struct file *file, unsigned int cmd,
		unsigned long arg)
		{
		switch (_IOC_NR(cmd)) {
		case _IOC_NR(PERF_EVENT_IOC_SET_FILTER):
		case _IOC_NR(PERF_EVENT_IOC_ID):
		/* Fix up pointer size (usually 4 -> 8 in 32-on-64-bit case */
		if (_IOC_SIZE(cmd) == sizeof(compat_uptr_t)) {
		cmd &= ~IOCSIZE_MASK;
		cmd \|= sizeof(void *) << IOCSIZE_SHIFT;
		}
		break;
		}
		return perf_ioctl(file, cmd, arg);
		}
		#else
		# define perf_compat_ioctl NULL
		#endif

		int perf_event_task_enable(void)
		{
		struct perf_event *event;
		@@ -4222,7 +4243,7 @@ static const struct file_operations perf_fops = {
		.read = perf_read,
		.poll = perf_poll,
		.unlocked_ioctl = perf_ioctl,
		.compat_ioctl = perf_ioctl,
		.compat_ioctl = perf_compat_ioctl,
		.mmap = perf_mmap,
		.fasync = perf_fasync,
		};

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