From 3ff1e922c22dcc68274b16fcce080cd69b69b47b Mon Sep 17 00:00:00 2001 From: Gabe Black Date: Tue, 9 Jun 2009 23:41:03 -0700 Subject: ARM: Add a cmpxchg implementation to the "comm page". This implementation does what it's supposed to (I think), but it's not atomic and doesn't have memory barriers like the kernel's version. --- src/arch/arm/linux/process.cc | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'src') diff --git a/src/arch/arm/linux/process.cc b/src/arch/arm/linux/process.cc index 620bcf116..bc6388b73 100644 --- a/src/arch/arm/linux/process.cc +++ b/src/arch/arm/linux/process.cc @@ -482,6 +482,18 @@ ArmLinuxProcess::startup() swiNeg1, sizeof(swiNeg1)); } + // This -should- be atomic, but I don't think all the support that we'd + // need is implemented. There should also be memory barriers around it. + uint8_t cmpxchg[] = + { + 0x00, 0x30, 0x92, 0xe5, //ldr r3, [r2] + 0x00, 0x30, 0x53, 0xe0, //subs r3, r3, r0 + 0x00, 0x10, 0x92, 0x05, //streq r1, [r2] + 0x03, 0x00, 0xa0, 0xe1, //mov r0, r3 + 0x0e, 0xf0, 0xa0, 0xe1 //usr_ret lr + }; + tc->getMemPort()->writeBlob(commPage + 0x0fc0, cmpxchg, sizeof(cmpxchg)); + uint8_t get_tls[] = { 0x08, 0x00, 0x9f, 0xe5, //ldr r0, [pc, #(16 - 8)] -- cgit v1.2.3