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tcg: Release mmap_lock on translation fault

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Turn helper_retaddr into a multi-state flag that may now also
indicate when we're performing a read on behalf of the translator.
In this case, release the mmap_lock before the longjmp back to
the main cpu loop, and thereby avoid a failing assert therein.

Fixes: https://bugs.launchpad.net/qemu/+bug/1832353
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2019-07-09 10:33:36 +02:00
parent 2fbb2353ce
commit 52ba13f042
2 changed files with 63 additions and 23 deletions
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66
accel/tcg/user-exec.c
View File

@ -64,27 +64,56 @@ static inline int handle_cpu_signal(uintptr_t pc, siginfo_t *info,
CPUState *cpu = current_cpu;
CPUClass *cc;
unsigned long address = (unsigned long)info->si_addr;
MMUAccessType access_type;
MMUAccessType access_type = is_write ? MMU_DATA_STORE : MMU_DATA_LOAD;
/* We must handle PC addresses from two different sources:
* a call return address and a signal frame address.
*
* Within cpu_restore_state_from_tb we assume the former and adjust
* the address by -GETPC_ADJ so that the address is within the call
* insn so that addr does not accidentally match the beginning of the
* next guest insn.
*
* However, when the PC comes from the signal frame, it points to
* the actual faulting host insn and not a call insn. Subtracting
* GETPC_ADJ in that case may accidentally match the previous guest insn.
*
* So for the later case, adjust forward to compensate for what
* will be done later by cpu_restore_state_from_tb.
*/
if (helper_retaddr) {
switch (helper_retaddr) {
default:
/*
* Fault during host memory operation within a helper function.
* The helper's host return address, saved here, gives us a
* pointer into the generated code that will unwind to the
* correct guest pc.
*/
pc = helper_retaddr;
} else {
break;
case 0:
/*
* Fault during host memory operation within generated code.
* (Or, a unrelated bug within qemu, but we can't tell from here).
*
* We take the host pc from the signal frame. However, we cannot
* use that value directly. Within cpu_restore_state_from_tb, we
* assume PC comes from GETPC(), as used by the helper functions,
* so we adjust the address by -GETPC_ADJ to form an address that
* is within the call insn, so that the address does not accidentially
* match the beginning of the next guest insn. However, when the
* pc comes from the signal frame it points to the actual faulting
* host memory insn and not the return from a call insn.
*
* Therefore, adjust to compensate for what will be done later
* by cpu_restore_state_from_tb.
*/
pc += GETPC_ADJ;
break;
case 1:
/*
* Fault during host read for translation, or loosely, "execution".
*
* The guest pc is already pointing to the start of the TB for which
* code is being generated. If the guest translator manages the
* page crossings correctly, this is exactly the correct address
* (and if the translator doesn't handle page boundaries correctly
* there's little we can do about that here). Therefore, do not
* trigger the unwinder.
*
* Like tb_gen_code, release the memory lock before cpu_loop_exit.
*/
pc = 0;
access_type = MMU_INST_FETCH;
mmap_unlock();
break;
}
/* For synchronous signals we expect to be coming from the vCPU
@ -155,7 +184,6 @@ static inline int handle_cpu_signal(uintptr_t pc, siginfo_t *info,
clear_helper_retaddr();
cc = CPU_GET_CLASS(cpu);
access_type = is_write ? MMU_DATA_STORE : MMU_DATA_LOAD;
cc->tlb_fill(cpu, address, 0, access_type, MMU_USER_IDX, false, pc);
g_assert_not_reached();
}

20
include/exec/cpu_ldst_useronly_template.h
View File

@ -64,12 +64,18 @@
static inline RES_TYPE
glue(glue(cpu_ld, USUFFIX), MEMSUFFIX)(CPUArchState *env, abi_ptr ptr)
{
#if !defined(CODE_ACCESS)
#ifdef CODE_ACCESS
RES_TYPE ret;
set_helper_retaddr(1);
ret = glue(glue(ld, USUFFIX), _p)(g2h(ptr));
clear_helper_retaddr();
return ret;
#else
trace_guest_mem_before_exec(
env_cpu(env), ptr,
trace_mem_build_info(SHIFT, false, MO_TE, false));
#endif
return glue(glue(ld, USUFFIX), _p)(g2h(ptr));
#endif
}
#ifndef CODE_ACCESS
@ -90,12 +96,18 @@ glue(glue(glue(cpu_ld, USUFFIX), MEMSUFFIX), _ra)(CPUArchState *env,
static inline int
glue(glue(cpu_lds, SUFFIX), MEMSUFFIX)(CPUArchState *env, abi_ptr ptr)
{
#if !defined(CODE_ACCESS)
#ifdef CODE_ACCESS
int ret;
set_helper_retaddr(1);
ret = glue(glue(lds, SUFFIX), _p)(g2h(ptr));
clear_helper_retaddr();
return ret;
#else
trace_guest_mem_before_exec(
env_cpu(env), ptr,
trace_mem_build_info(SHIFT, true, MO_TE, false));
#endif
return glue(glue(lds, SUFFIX), _p)(g2h(ptr));
#endif
}
#ifndef CODE_ACCESS