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accel/tcg/translate-all: expand cpu_restore_state addr check 

We are still seeing signals during translation time when we walk over
a page protection boundary. This expands the check to ensure the host
PC is inside the code generation buffer. The original suggestion was
to check versus tcg_ctx.code_gen_ptr but as we now segment the
translation buffer we have to settle for just a general check for
being inside.

I've also fixed up the declaration to make it clear it can deal with
invalid addresses. A later patch will fix up the call sites.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20171108153245.20740-2-alex.bennee@linaro.org
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Tested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Alex Bennée 2017-11-13 13:55:27 +00:00 committed by Peter Maydell
parent 7264961934
commit d25f2a7227
2 changed files with 39 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
accel/tcg/translate-all.c
View File

@ -352,28 +352,33 @@ static int cpu_restore_state_from_tb(CPUState *cpu, TranslationBlock *tb,
return 0;
}
bool cpu_restore_state(CPUState *cpu, uintptr_t retaddr)
bool cpu_restore_state(CPUState *cpu, uintptr_t host_pc)
{
TranslationBlock *tb;
bool r = false;
uintptr_t check_offset;
/* A retaddr of zero is invalid so we really shouldn't have ended
* up here. The target code has likely forgotten to check retaddr
* != 0 before attempting to restore state. We return early to
* avoid blowing up on a recursive tb_lock(). The target must have
* previously survived a failed cpu_restore_state because
* tb_find_pc(0) would have failed anyway. It still should be
* fixed though.
/* The host_pc has to be in the region of current code buffer. If
* it is not we will not be able to resolve it here. The two cases
* where host_pc will not be correct are:
*
* - fault during translation (instruction fetch)
* - fault from helper (not using GETPC() macro)
*
* Either way we need return early to avoid blowing up on a
* recursive tb_lock() as we can't resolve it here.
*
* We are using unsigned arithmetic so if host_pc <
* tcg_init_ctx.code_gen_buffer check_offset will wrap to way
* above the code_gen_buffer_size
*/
check_offset = host_pc - (uintptr_t) tcg_init_ctx.code_gen_buffer;
if (!retaddr) {
return r;
}
if (check_offset < tcg_init_ctx.code_gen_buffer_size) {
tb_lock();
tb = tb_find_pc(retaddr);
tb = tb_find_pc(host_pc);
if (tb) {
cpu_restore_state_from_tb(cpu, tb, retaddr);
cpu_restore_state_from_tb(cpu, tb, host_pc);
if (tb->cflags & CF_NOCACHE) {
/* one-shot translation, invalidate it immediately */
tb_phys_invalidate(tb, -1);
@ -382,6 +387,7 @@ bool cpu_restore_state(CPUState *cpu, uintptr_t retaddr)
r = true;
}
tb_unlock();
}
return r;
}

11
include/exec/exec-all.h
View File

@ -45,6 +45,17 @@ void restore_state_to_opc(CPUArchState *env, struct TranslationBlock *tb,
target_ulong *data);
void cpu_gen_init(void);
/**
* cpu_restore_state:
* @cpu: the vCPU state is to be restore to
* @searched_pc: the host PC the fault occurred at
* @return: true if state was restored, false otherwise
*
* Attempt to restore the state for a fault occurring in translated
* code. If the searched_pc is not in translated code no state is
* restored and the function returns false.
*/
bool cpu_restore_state(CPUState *cpu, uintptr_t searched_pc);
void QEMU_NORETURN cpu_loop_exit_noexc(CPUState *cpu);