I have a new comprehension about the question according to your clue The "SP" register(R13) is a banked register, there is a corresponding physical register for each processor mode(abort fiq irq svc und ...), so in this case, when a normal interrupt exception occurs, the processor(arm core) auto enter irq mode, then the "SP"(R14) is "R14_irq", so the SP isn't the pointer of kernel stack.
I don't know this comprehension is correct or no? According to this comprehension, there is also an uncertainty. where is the "R14_irq" register initialized? -----邮件原件----- 发件人: Pei Lin [mailto:[email protected]] 发送时间: 2009年7月31日 10:29 收件人: 付新荣 抄送: [email protected]; Kernelnewbies 主题: Re: 答复: 答复: Ecartis command results: appsub kernelnewbies [email protected] 4A71650B:26CF.1:xrearyarjovrf see the comment " * SP points to a minimal amount of processor-private memory, the address * of which is copied into r0 for the mode specific abort handler. " i think here it build a stack for exception handling. BRs Lin 2009/7/31 付新荣 <[email protected]>: > Thank you for your reply! > > I make a mistake before. > The "sp" should decrement before storing rather than after. > So it's should "stmdb sp, {r0, lr}" > The "stmdb" is equivalent to "stmfd". > So i am in accordance with u in this matter! > > But, > How to explain the "stmia sp, {r0, lr}" of the micros "vector_stub" > defined in file "arch/arm/kernel/entry-armv.S". > > Are there different comprehension in this problem? > > Thax! > > -----邮件原件----- > 发件人: [email protected] > [mailto:[email protected]] 代表 [email protected] > 发送时间: 2009年7月30日 22:01 > 收件人: Kernelnewbies > 主题: Re: 答复: Ecartis command results: appsub kernelnewbies > [email protected] 4A71650B:26CF.1:xrearyarjovrf > > On Thu, 30 Jul 2009 18:07:18 +0800, 付新荣 <[email protected]> > wrote: >> hi,everybody. >> I don't know why use the "stmia sp, {r0, lr}" instruction rather than >> "stmda sp, {r0, lr}" in the macros "vector_stub" defined in file >> "arch/arm/kernel/entry-armv.S". >> >> becaue the "sp" register is point to the kernel stack top. >> The "sp" register is initialized with "init_thread_union + > THREAD_START_SP" >> >> >> Kernel stack: >> ======================================================================= >> Lower address >> higher address >> | init_thread_union| <-------stack content--------| >> sp >> |<----------------------------8K bytes--------------------------->| >> ======================================================================= >> >> According to the Kernel stack mechanism，I think that it should be > "stmda >> sp, {r0, lr}" and the SP should decrement. >> >> -----邮件原件----- >> 发件人: Ecartis [mailto:[email protected]] >> 发送时间: 2009年7月30日 17:39 >> 收件人: 付新荣 >> 主题: Ecartis command results: appsub kernelnewbies >> [email protected] 4A71650B:26CF.1:xrearyarjovrf >> >> >> List context changed to 'kernelnewbies' by following command. >>>> appsub kernelnewbies [email protected] >>>> 4A71650B:26CF.1:xrearyarjovrf >> Subscribed. >> >> --- >> Ecartis v1.0.0 - job execution complete. >> >> >> -- >> To unsubscribe from this list: send an email with >> "unsubscribe kernelnewbies" to [email protected] >> Please read the FAQ at http://kernelnewbies.org/FAQ > > Hi, > > I don't know the intrinsics of the kernel stack, but the stack described is > indeed a full descending stack. > If pushing on the stack, it's more common to use the stmfd instruction > though. (IOW store on a full descending stack) > I guess it depends whether the excerpt of code is aiming to push or to pop > the stack. > It should be pushing, since the sp is the destination for the storing of > all registers + link register... > > B rgds > Kris > > > -- > To unsubscribe from this list: send an email with > "unsubscribe kernelnewbies" to [email protected] > Please read the FAQ at http://kernelnewbies.org/FAQ > > > -- > To unsubscribe from this list: send an email with > "unsubscribe kernelnewbies" to [email protected] > Please read the FAQ at http://kernelnewbies.org/FAQ > > -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to [email protected] Please read the FAQ at http://kernelnewbies.org/FAQ
