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author | Ilya Leoshkevich <iii@linux.ibm.com> | 2022-07-11 20:56:38 +0200 |
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committer | Richard Henderson <richard.henderson@linaro.org> | 2022-07-12 10:43:33 +0530 |
commit | b0f650f0477ae775e0915e3d60ab5110ad5e9157 (patch) | |
tree | ae709274082e661508bfa4ea9879c702ba6b5d02 /accel | |
parent | ba8924113ca459d02ee67656a713f7ff494b968e (diff) | |
download | qemu-b0f650f0477ae775e0915e3d60ab5110ad5e9157.zip qemu-b0f650f0477ae775e0915e3d60ab5110ad5e9157.tar.gz qemu-b0f650f0477ae775e0915e3d60ab5110ad5e9157.tar.bz2 |
accel/tcg: Fix unaligned stores to s390x low-address-protected lowcore
If low-address-protection is active, unaligned stores to non-protected
parts of lowcore lead to protection exceptions. The reason is that in
such cases tlb_fill() call in store_helper_unaligned() covers
[0, addr + size) range, which contains the protected portion of
lowcore. This range is too large.
The most straightforward fix would be to make sure we stay within the
original [addr, addr + size) range. However, if an unaligned access
affects a single page, we don't need to call tlb_fill() in
store_helper_unaligned() at all, since it would be identical to
the previous tlb_fill() call in store_helper(), and therefore a no-op.
If an unaligned access covers multiple pages, this situation does not
occur.
Therefore simply skip TLB handling in store_helper_unaligned() if we
are dealing with a single page.
Fixes: 2bcf018340cb ("s390x/tcg: low-address protection support")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20220711185640.3558813-2-iii@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Diffstat (limited to 'accel')
-rw-r--r-- | accel/tcg/cputlb.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c index f90f431..a46f3a6 100644 --- a/accel/tcg/cputlb.c +++ b/accel/tcg/cputlb.c @@ -2248,7 +2248,7 @@ store_helper_unaligned(CPUArchState *env, target_ulong addr, uint64_t val, const size_t tlb_off = offsetof(CPUTLBEntry, addr_write); uintptr_t index, index2; CPUTLBEntry *entry, *entry2; - target_ulong page2, tlb_addr, tlb_addr2; + target_ulong page1, page2, tlb_addr, tlb_addr2; MemOpIdx oi; size_t size2; int i; @@ -2256,15 +2256,17 @@ store_helper_unaligned(CPUArchState *env, target_ulong addr, uint64_t val, /* * Ensure the second page is in the TLB. Note that the first page * is already guaranteed to be filled, and that the second page - * cannot evict the first. + * cannot evict the first. An exception to this rule is PAGE_WRITE_INV + * handling: the first page could have evicted itself. */ + page1 = addr & TARGET_PAGE_MASK; page2 = (addr + size) & TARGET_PAGE_MASK; size2 = (addr + size) & ~TARGET_PAGE_MASK; index2 = tlb_index(env, mmu_idx, page2); entry2 = tlb_entry(env, mmu_idx, page2); tlb_addr2 = tlb_addr_write(entry2); - if (!tlb_hit_page(tlb_addr2, page2)) { + if (page1 != page2 && !tlb_hit_page(tlb_addr2, page2)) { if (!victim_tlb_hit(env, mmu_idx, index2, tlb_off, page2)) { tlb_fill(env_cpu(env), page2, size2, MMU_DATA_STORE, mmu_idx, retaddr); |