Merge pull request #8965 from hrydgard/exynos-cache-fix

Port over the Exynos cacheline size fix from Dolphin.

Common/Arm64Emitter.cpp

@@ -313,24 +313,40 @@ void ARM64XEmitter::FlushIcache()
 
 void ARM64XEmitter::FlushIcacheSection(u8* start, u8* end)
 {
-	if (cpu_info.sBugs.bExynos8890Invalidation)
-	{
-		// Over invalidate to force this CPU to listen.
-		start = m_startcode + 4096 < start ? start - 4096 : m_startcode;
-		end += 4096;
-	}
-
 #if defined(IOS)
 	// Header file says this is equivalent to: sys_icache_invalidate(start, end - start);
 	sys_cache_control(kCacheFunctionPrepareForExecution, start, end - start);
-#else
-#if (defined(__clang__) && !defined(_M_IX86) && !defined(_M_X64)) || defined(ANDROID)
-	__clear_cache(start, end);
-#else
-#if !defined(_M_IX86) && !defined(_M_X64)
-	__builtin___clear_cache(start, end);
-#endif
-#endif
+#elif !defined(_M_IX86) && !defined(_M_X64)
+	// Code from Dolphin, contributed by the Mono project.
+
+	// Don't rely on GCC's __clear_cache implementation, as it caches
+	// icache/dcache cache line sizes, that can vary between cores on
+	// big.LITTLE architectures.
+	u64 addr, ctr_el0;
+	static size_t icache_line_size = 0xffff, dcache_line_size = 0xffff;
+	size_t isize, dsize;
+
+	__asm__ volatile("mrs %0, ctr_el0" : "=r"(ctr_el0));
+	isize = 4 << ((ctr_el0 >> 0) & 0xf);
+	dsize = 4 << ((ctr_el0 >> 16) & 0xf);
+
+	// use the global minimum cache line size
+	icache_line_size = isize = icache_line_size < isize ? icache_line_size : isize;
+	dcache_line_size = dsize = dcache_line_size < dsize ? dcache_line_size : dsize;
+
+	addr = (u64)start & ~(u64)(dsize - 1);
+	for (; addr < (u64)end; addr += dsize)
+		// use "civac" instead of "cvau", as this is the suggested workaround for
+		// Cortex-A53 errata 819472, 826319, 827319 and 824069.
+		__asm__ volatile("dc civac, %0" : : "r"(addr) : "memory");
+	__asm__ volatile("dsb ish" : : : "memory");
+
+	addr = (u64)start & ~(u64)(isize - 1);
+	for (; addr < (u64)end; addr += isize)
+		__asm__ volatile("ic ivau, %0" : : "r"(addr) : "memory");
+
+	__asm__ volatile("dsb ish" : : : "memory");
+	__asm__ volatile("isb" : : : "memory");
 #endif
 }
 

Common/CPUDetect.h

@@ -89,14 +89,15 @@ struct CPUInfo {
 	bool bXBurst1;
 	bool bXBurst2;
 
-	// Bugs
+	// Quirks
 	struct {
-		// Samsung Galaxy S7 devices (Exynos 8890) have a bug that causes invalidation to work incorrectly.
-		// This may be caused by interaction between the separate CPU cores.
-		// Padding jit blocks and over-invalidating seems to "solve" it.
-		// Only affects ARM64.
-		bool bExynos8890Invalidation;
-	} sBugs;
+		// Samsung Galaxy S7 devices (Exynos 8890) have a big.LITTLE configuration where the cacheline size differs between big and LITTLE.
+		// GCC's cache clearing function would detect the cacheline size on one and keep it for later. When clearing
+		// with the wrong cacheline size on the other, that's an issue. In case we want to do something different in this
+		// situation in the future, let's keep this as a quirk, but our current code won't detect it reliably
+		// if it happens on new archs. We now use better clearing code on ARM64 that doesn't have this issue.
+		bool bExynos8890DifferingCachelineSizes;
+	} sQuirks;
 
 	// Call Detect()
 	explicit CPUInfo();

Core/MIPS/ARM64/Arm64Jit.cpp

@@ -333,14 +333,6 @@ const u8 *Arm64Jit::DoJit(u32 em_address, JitBlock *b) {
 	if (dontLogBlocks > 0)
 		dontLogBlocks--;
 
-	if (cpu_info.sBugs.bExynos8890Invalidation) {
-		// What a waste.  If we don't do both this and over-invalidate, the device crashes.
-		// This space won't ever get run, but it's wasted jit cache space.
-		for (int i = 0; i < 32; ++i) {
-			HINT(HINT_NOP);
-		}
-	}
-
 	// Don't forget to zap the newly written instructions in the instruction cache!
 	FlushIcache();
 

GPU/Common/VertexDecoderArm64.cpp

@@ -278,14 +278,6 @@ JittedVertexDecoder VertexDecoderJitCache::Compile(const VertexDecoder &dec, int
 
 	RET();
 
-	if (cpu_info.sBugs.bExynos8890Invalidation) {
-		// Apparently the vertex cache hasn't been the problem, but adding this here for the same
-		// reasons as the standard jit.
-		for (int i = 0; i < 32; ++i) {
-			HINT(HINT_NOP);
-		}
-	}
-
 	FlushIcache();
 
 	if (log) {

android/jni/app-android.cpp

@@ -526,7 +526,7 @@ extern "C" void Java_org_ppsspp_ppsspp_NativeApp_init
 	// Unfortunately, on the Samsung Galaxy S7, this isn't in /proc/cpuinfo.
 	// We also can't read it from __system_property_get.
 	if (buildBoard == "universal8890") {
-		cpu_info.sBugs.bExynos8890Invalidation = true;
+		cpu_info.sQuirks.bExynos8890DifferingCachelineSizes = true;
 	}
 
 	NativeGetAppInfo(&app_name, &app_nice_name, &landscape, &version);