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arm64: IPI each CPU after invalidating the I-cache for kernel mappings

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When invalidating the instruction cache for a kernel mapping via
flush_icache_range(), it is also necessary to flush the pipeline for
other CPUs so that instructions fetched into the pipeline before the
I-cache invalidation are discarded. For example, if module 'foo' is
unloaded and then module 'bar' is loaded into the same area of memory,
a CPU could end up executing instructions from 'foo' when branching into
'bar' if these instructions were fetched into the pipeline before 'foo'
was unloaded.

Whilst this is highly unlikely to occur in practice, particularly as
any exception acts as a context-synchronizing operation, following the
letter of the architecture requires us to execute an ISB on each CPU
in order for the new instruction stream to be visible.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Will Deacon
2018-06-11 14:22:09 +01:00
parent 7373fed2f2
commit 3b8c9f1cdf
4 changed files with 33 additions and 18 deletions
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18
arch/arm64/kernel/insn.c
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@@ -216,8 +216,8 @@ int __kprobes aarch64_insn_patch_text_nosync(void *addr, u32 insn)
ret = aarch64_insn_write(tp, insn);
if (ret == 0)
flush_icache_range((uintptr_t)tp,
(uintptr_t)tp + AARCH64_INSN_SIZE);
__flush_icache_range((uintptr_t)tp,
(uintptr_t)tp + AARCH64_INSN_SIZE);
return ret;
}
@@ -283,18 +283,8 @@ int __kprobes aarch64_insn_patch_text(void *addrs[], u32 insns[], int cnt)
if (ret)
return ret;
if (aarch64_insn_hotpatch_safe(insn, insns[0])) {
/*
* ARMv8 architecture doesn't guarantee all CPUs see
* the new instruction after returning from function
* aarch64_insn_patch_text_nosync(). So send IPIs to
* all other CPUs to achieve instruction
* synchronization.
*/
ret = aarch64_insn_patch_text_nosync(addrs[0], insns[0]);
kick_all_cpus_sync();
return ret;
}
if (aarch64_insn_hotpatch_safe(insn, insns[0]))
return aarch64_insn_patch_text_nosync(addrs[0], insns[0]);
}
return aarch64_insn_patch_text_sync(addrs, insns, cnt);