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Re: [Qemu-devel] [PATCH] softmmu: fixing usage of cpu_st/ld* from helper
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PATCH] softmmu: fixing usage of cpu_st/ld* from helpers |
Date: |
Mon, 15 Sep 2014 09:28:28 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.1.0 |
On 09/15/2014 03:50 AM, Pavel Dovgalyuk wrote:
> +/* inline helper ld function */
> +
> +static inline DATA_TYPE
> +glue(glue(helper_inline_ld, SUFFIX), MEMSUFFIX)(CPUArchState *env,
> + target_ulong addr,
> + int mmu_idx)
> +{
> + return glue(glue(helper_call_ld, SUFFIX), MMUSUFFIX)(env, addr, mmu_idx,
> + GETRA());
> +}
You'd have to mark this always_inline to make absolutely sure that the caller's
GETRA value is used. That said...
> @@ -76,7 +87,8 @@ glue(glue(cpu_ld, USUFFIX), MEMSUFFIX)(CPUArchState *env,
> target_ulong ptr)
> mmu_idx = CPU_MMU_INDEX;
> if (unlikely(env->tlb_table[mmu_idx][page_index].ADDR_READ !=
> (addr & (TARGET_PAGE_MASK | (DATA_SIZE - 1))))) {
> - res = glue(glue(helper_ld, SUFFIX), MMUSUFFIX)(env, addr, mmu_idx);
> + res = glue(glue(helper_inline_ld, SUFFIX), MEMSUFFIX)(env, addr,
> + mmu_idx);
> } else {
> uintptr_t hostaddr = addr +
> env->tlb_table[mmu_idx][page_index].addend;
> res = glue(glue(ld, USUFFIX), _raw)(hostaddr);
... this is also the wrong context.
The only GETRA value that helps you at all is the one from the *top level*
helper -- the one that's directly called from TCG code. So, in the case of
maskmov, helper_maskmov_xmm. Anything else and you aren't getting the call
site address from the TCG code, and so can't be used to detect the PC of the
MMU fault.
I guess there are only two real possibilities:
(1) Have the cpu_ldst_template helpers all be marked always_inline so that they
could use GETRA. I'm not too fond of this because we'd still get the wrong
results if these are not used from top-level helpers.
(2) Add helpers that accept the GETRA value from the top-level helper. And not
hidden within a macro or always_inline function. This helps us see what
portions of the code have been audited for the new interface. This will
involve quite a bit more code churn, but shouldn't been too difficult for any
single function.
r~