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Commit f2053f1a authored by Anton Blanchard's avatar Anton Blanchard Committed by Benjamin Herrenschmidt
Browse files

powerpc/perf_counter: Fix vdso detection 



perf_counter uses arch_vma_name() to detect a vdso region which in turn uses
current->mm->context.vdso_base. We need to initialise this before doing
the mmap or else we fail to detect the vdso.

Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 8bbde7a7

arch/powerpc/kernel/vdso.c

+10 −4
Original line number Diff line number Diff line
@@ -240,6 +240,13 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 
		goto fail_mmapsem;

	}



	/*

	 * Put vDSO base into mm struct. We need to do this before calling

	 * install_special_mapping or the perf counter mmap tracking code

	 * will fail to recognise it as a vDSO (since arch_vma_name fails).

	 */

	current->mm->context.vdso_base = vdso_base;



	/*

	 * our vma flags don't have VM_WRITE so by default, the process isn't

	 * allowed to write those pages.
@@ -260,11 +267,10 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 
				     VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|

				     VM_ALWAYSDUMP,

				     vdso_pagelist);

	if (rc)

	if (rc) {

		current->mm->context.vdso_base = 0;

		goto fail_mmapsem;



	/* Put vDSO base into mm struct */

	current->mm->context.vdso_base = vdso_base;

	}



	up_write(&mm->mmap_sem);

	return 0;