[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Bug 1868527] Re: alignment may overlap the TLB flags
From: |
Hansni Bu |
Subject: |
[Bug 1868527] Re: alignment may overlap the TLB flags |
Date: |
Tue, 24 Mar 2020 01:32:16 -0000 |
This is an inspection yet.
For ARM SMMU simulation, TARGET_PAGE_BITS_MIN is 10. All low bits of the TLB
virtual address are used up by TLB flags and alignment flags. It's a little
crowded.
/*
* ARMv7 and later CPUs have 4K pages minimum, but ARMv5 and v6
* have to support 1K tiny pages.
*/
# define TARGET_PAGE_BITS_VARY
# define TARGET_PAGE_BITS_MIN 10
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1868527
Title:
alignment may overlap the TLB flags
Status in QEMU:
Incomplete
Bug description:
Hi,
In QEMU-4.2.0, or git-9b26a610936deaf436af9b7e39e4b7f0a35e4409, alignment may
overlap the TLB flags.
For example, the alignment: MO_ALIGN_32,
MO_ALIGN_32 = 5 << MO_ASHIFT,
and the TLB flag: TLB_DISCARD_WRITE
#define TLB_DISCARD_WRITE (1 << (TARGET_PAGE_BITS_MIN - 6))
then, in the function "get_alignment_bits", the assert may fail:
#if defined(CONFIG_SOFTMMU)
/* The requested alignment cannot overlap the TLB flags. */
tcg_debug_assert((TLB_FLAGS_MASK & ((1 << a) - 1)) == 0);
#endif
However, the alignment of MO_ALIGN_32 is not used for now, so the
assert cannot be triggered in current version. Anyway it seems like a
potential conflict.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1868527/+subscriptions