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cputlb: Don't assume do_unassigned_access() never returns

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In get_page_addr_code(), if the guest PC doesn't correspond to RAM
then we currently run the CPU's do_unassigned_access() hook if it has
one, and otherwise we give up and exit QEMU with a more-or-less
useful message. This code assumes that the do_unassigned_access hook
will never return, because if it does then we'll plough on attempting
to use a non-RAM TLB entry to get a RAM address and will abort() in
qemu_ram_addr_from_host_nofail(). Unfortunately some CPU
implementations of this hook do return: Microblaze, SPARC and the ARM
v7M.

Change the code to call report_bad_exec() if the hook returns, as
well as if it didn't have one. This means we can tidy it up to use
the cpu_unassigned_access() function which wraps the "get the CPU
class and call the hook if it has one" work, since we aren't trying
to distinguish "no hook" from "hook existed and returned" any more.

This brings the handling of this hook into line with the handling
used for data accesses, where "hook returned" is treated the
same as "no hook existed" and gets you the default behaviour.

Backports commit 44d7ce0ef39cb45e13d384574d79799eb3d39834 from qemu
This commit is contained in:
Peter Maydell 2018-03-02 10:41:17 -05:00 committed by Lioncash
parent 4114fb2c0e
commit 0c9ef6f4b3
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GPG key ID: 4E3C3CC1031BA9C7
1 changed files with 8 additions and 11 deletions
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19
qemu/cputlb.c
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@ -313,17 +313,14 @@ tb_page_addr_t get_page_addr_code(CPUArchState *env1, target_ulong addr)
pd = iotlbentry->addr & ~TARGET_PAGE_MASK;
mr = iotlb_to_region(cpu, pd, iotlbentry->attrs);
if (memory_region_is_unassigned(cpu->uc, mr)) {
CPUClass *cc = CPU_GET_CLASS(env1->uc, cpu);
if (cc->do_unassigned_access) {
cc->do_unassigned_access(cpu, addr, false, true, 0, 4);
} else {
//cpu_abort(cpu, "Trying to execute code outside RAM or ROM at 0x"
// TARGET_FMT_lx "\n", addr); // qq
env1->invalid_addr = addr;
env1->invalid_error = UC_ERR_FETCH_UNMAPPED;
return RAM_ADDR_INVALID;
}
cpu_unassigned_access(cpu, addr, false, true, 0, 4);
/* The CPU's unassigned access hook might have longjumped out
* with an exception. If it didn't (or there was no hook) then
* we can't proceed further.
*/
env1->invalid_addr = addr;
env1->invalid_error = UC_ERR_FETCH_UNMAPPED;
return RAM_ADDR_INVALID;
}
p = (void *)((uintptr_t)addr + env1->tlb_table[mmu_idx][page_index].addend);
ram_addr = qemu_ram_addr_from_host_nofail(cpu->uc, p);