Greetings. I have moved forward to tests in my our MIPS port. Some of them work fine, but not all. Now I have a question about syscall.c test. What exactly we test here? In ARM-based part I see initialisation of 12 registers, performing syscall with further checking that our initialised registers have original values. So, as far I understand, these registers should be modified in a syscall’s inline, thus, they should be allocated on the stack and reloaded after the end of syscall. Right? My issue here is that I have much many than 12 registers and my compiler chooses them randomly (for me). For example, sometimes it uses only S0-S7 with some T0-T9 registers, sometimes all T0-T9 with some S0-S7 registers. Moreover, I cannot put more than 30 asm instructions in one inline (gcc error), thus, maybe I should specify proper register name here. But for that, I should be sure that I understand this test correct. Can we help me? Thank you -- Vasily A. Sartakov sartakov@ksyslabs.org
Hi Vasily, The point of the syscall.c tests is to check that registers are not being corrupted by our syscalls (i.e that the kernel ABI + stubs follows the calling convention of the architecture). For arm, this just means checking any registers that are not caller saved are preserved across the system calls. Not sure what this means for MIPS, but hopefully that clears it up? Cheers, Anna. -----Original Message----- From: Devel [mailto:devel-bounces@sel4.systems] On Behalf Of Vasily A. Sartakov Sent: Monday, 10 October 2016 10:09 PM To: devel@sel4.systems Subject: [seL4] syscall.c Greetings. I have moved forward to tests in my our MIPS port. Some of them work fine, but not all. Now I have a question about syscall.c test. What exactly we test here? In ARM-based part I see initialisation of 12 registers, performing syscall with further checking that our initialised registers have original values. So, as far I understand, these registers should be modified in a syscall’s inline, thus, they should be allocated on the stack and reloaded after the end of syscall. Right? My issue here is that I have much many than 12 registers and my compiler chooses them randomly (for me). For example, sometimes it uses only S0-S7 with some T0-T9 registers, sometimes all T0-T9 with some S0-S7 registers. Moreover, I cannot put more than 30 asm instructions in one inline (gcc error), thus, maybe I should specify proper register name here. But for that, I should be sure that I understand this test correct. Can we help me? Thank you -- Vasily A. Sartakov sartakov@ksyslabs.org _______________________________________________ Devel mailing list Devel@sel4.systems https://sel4.systems/lists/listinfo/devel
Greetings Thank you for your answer
The point of the syscall.c tests is to check that registers are not being corrupted by our syscalls (i.e that the kernel ABI + stubs follows the calling convention of the architecture).
…and corruption of registers can happen only if syscalls modify stack, since these values are popped from it after the end of a syscall routine, right?
For arm, this just means checking any registers that are not caller saved are preserved across the system calls. Not sure what this means for MIPS, but hopefully that clears it up?
-- Vasily A. Sartakov sartakov@ksyslabs.org
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Anna.Lyons＠data61.csiro.au -
Vasily A. Sartakov