What version of Go are you using (go version)?
go version 1.15
Does this issue reproduce with the latest release?
No
What operating system and processor architecture are you using (go env)?
Linux 5.4.54-1.0.0.std7c.el7.2.x86_64 #1 SMP Mon Nov 16 10:02:20 CST 2020 x86_64 x86_64 x86_64 GNU/Linux
What did you see instead?
Below is a screenshot of the abnormal machine
What did you do?
The memory usage is too high, but there is no memory leak by analyzing the heap file of pprof.
The reason for this conclusion is:
My service is deployed on k8s, and there are other same services. The pprof file analysis results are similar to this problematic one (linux kernel version is 4.9.2-3.0.0.std7b.el7.5.x86_64 cmd/cgo: fails with gcc 4.4.1 #1 SMP Thu Apr 26 17:33:02 CST 2018 x86_64 x86_64 x86_64 GNU/Linux).
I refer to the MADV_FREE problem in the link below. By analyzing the LazyFree of the /proc/1/smaps file, I found that it is all 0, and all machines are linux kernel 4.5 or above. Logically, the same problem will occur, but it does not No. runtime: default to MADV_DONTNEED on Linux #42330
gotrace records are normal
What did you expect to see?
Why is the memory usage of this service high? What impact does Linux kernel version 5 and above have on golang memory management?
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It's not related to the kernel version.
Go 1.15 used MADV_FREE by default to release memory. This memory was released very lazily by the kernel resulting in larger RSS until the memory was actually needed elsewhere. Hence RSS didn't reflect anything close to the Go programs actual usage.
Go 1.16+ defaults to using MADV_DONTNEED, which results in memory being released much more promptly by the kernel.
See https://go.dev/doc/go1.16#runtime for more details.
You can use the GODEBUG=madvdontneed=1 environment variable on Go 1.15, or preferably upgrade to a supported version of Go (eg, Go 1.19). Go 1.20 will be released soon, so that would be a good target too.
I am going through the CXL support in Linux Kernel and I found that there is no function or support for cxl.cache. I'm confused if the cache part is not yet implemented in linux kernel or if the kernel should not have access to the cache commands?
(I have seen up to the latest Kernel release, 5.19)
I would like to know is there any caveats in using sched_clock()? Any case when it is not safe to use? And is it okay if I use it very early in kernel.bootup?
Btw the Linux runs on ARM platform
I am trying to run a Linux kernel as the secure OS on a TrustZone enabled development board(Samsung exynos 4412). Although somebody would say secure os should be small and simple. But I just want to try. And if it is possible, then write or port a trustlet application to this secure os will be easy, especially for applications with UI(trusted UI).
I bought the development board with a runnable secure OS based on Xv6 and the normal os is Android(android version 4.2.2, kernel version 3.0.15). I have tried to replace the simple secure os with the android Linux kernel, that is, with a little assembly code ahead, such as clearing the NS bit of SCR register, directly called the Linux kernel entry(with necessary kernel tagged list passed in).
The kernel uncompressed code is executed correctly and the first C function of the kernel, start_kernel(), is also executed. Almost all the initialization functions run well except running to calibrate_delay(). This function will wait for the jiffies changed:
/* wait for "start of" clock tick */
ticks = jiffies;
while (ticks == jiffies);
I guess the reason is no clock interrupt is generated(I print logs in clock interrupt callback functions, they are never gotten in). I have checked the CPSR state before and after the local_irq_enable() function. The IRQ and FIQ bit are set correctly. I also print some logs in the Linux kernel's IRQ handler defined in the interrupt vectors table. Nothing logged.
I know there may be some differences in interrupt system between secure world and non secure world. But I can't find the differences in any documentation. Can anybody point out them? And the most important question is, as Linux is a very complicated OS, can Linux kernel run as a TrustZone secure OS?
I am a newbie in Linux kernel and ARM TrustZone. Please help me.
Running Linux as a secure world OS should be standard by default. Ie, the secure world supervisor is the most trusted and can easily transition to the other modes. The secure world is an operating concept of the ARM CPU.
Note: Just because Linux runs in the secure world, doesn't make your system secure! TrustZone and the secure world are features that you can use to make a secure system.
But I just want to try. And if it is possible, then write or port a trustlet application to this secure os will be easy, especially for applications with UI(trusted UI).
TrustZone allows partitioning of software. If you run both Linux and the trustlet application in the same layer, there is no use. The trustlet is just a normal application.
The normal mode for trustlets is to setup a monitor vector page on boot and lock down physical access. The Linux kernel can then use the smc instruction to call routines in the trustlet to access DRM type functionality to decrypt media, etc. In this mode, Linux runs as a normal world OS, but can call limited functionality with-in the secure world through the SMC API you define.
Almost all the initialization functions run well except running to calibrate_delay().
This is symptomatic of non-functioning interrupts. calibrate_delay() runs a tight loop while waiting for a tick count to increase via system timer interrupts. If you are running in the secure world, you may need to route interrupts. The register GICD_ISPENDR can be used to force an interrupt. You may use this to verify that the ARM GIC is functioning properly. Also, the kernel command line option lpj=XXXXX (where XXXX is some number) can skip this step.
Most likely some peripheral interrupt router, clock configuration or other interrupt/timer initialization is done by a boot loader in a normal system and you are missing this. Booting a new board is always difficult; even more so with TrustZone.
There is nothing technically preventing Linux from running in the Secure state of an ARM processor. But it defeats the entire purpose of TrustZone. A large, complex kernel and OS such as Linux is infeasible to formally verify to the point that it can be considered "Secure".
For further reading on that aspect, see http://www.ok-labs.com/whitepapers/sample/sel4-formal-verification-of-an-os-kernel
As for the specific problem you are facing - there should be nothing special about interrupt handling in Secure vs. Non-secure state (unless you explicitly configure it to be different). But it could be that the secure OS you have removed was performing some initial timer initializations that are now not taking place.
Also 3.0.15 is an absolutely ancient kernel - it was released 2.5 years ago, based on something released over 3 years ago.
There are several issues with what you are saying that need to be cleared up. First, are you trying to get the Secure world kernel running or the Normal world kernel? You said you wanted to run Linux in the SW and Android in the NW, but your question stated, "I have tried to replace the simple secure os with the android Linux kernel". So which kernel are you having problems with?
Second, you mentioned clearing the NS-bit. This doesn't really make sense. If the NS-bit is set, clearing it requires means that you are running in the NW already (as the bit being set would indicate), you have executed a SMC instruction, switched to Monitor mode, set the NS-bit to 0, and then restored the SW registers. Is this the case?
As far as interrupts are concerned, have you properly initialized the VBAR for each execution mode, i.e. Secure world VBAR, Normal world VBAR, and MVBAR. All three will need to be setup, in addition to setting the proper values in the NSACR and others to ensure interrupts are channeled to the correct execution world and not all just handled by the SW. Also, you do need separate exception vector tables and handlers for all three modes. You might be able to get away with only one set initially, but once you partition your memory system using the TZASC, you will need separate everything.
TZ requires a lot of configuration and is not simply handled by setting/unsetting the NS-bit. For the Exynos 4412, numerous TZ control registers that must be properly set in order to execute in the NW. Unfortunately, none of the information on them is covered in the Public version of the User's Guide. You need the full version in order to get all the values and address necessary to actually run a SW and NW kernel on this processor.
I am trying to learn about IPSec layer in Linux kernel using Trace 32 ICD. For that I am trying to trace packet flow from user land to Ethernet driver. Problem I'm facing is that Trace32 is not able to display inline functions in stackframe output and therefore are jumps in my flow.
I am just wondering if :
a) there is a way to disable inline feature for kernel function (or in any program) in GCC.
b) there is a way to add support for inline functions in Trace32 ICD tool.
In case answer for both a & b is no then I would like to know if there exits a workaround to my problem.
My linux version: Linux (bts) 3.0.1-rt11-svn9237 #2 PREEMPT RT Fri Dec 21 09:58:42 IST 2012 armv7l GNU/Linux
My GCC version: arm-none-linux-gnueabi-gcc-4.3.3