forked from luck/tmp_suning_uos_patched
bc6e8dc112
Newer Loongson cores (Loongson-3A R2 and newer) use the implementation-dependent ExcCode 16 to signal Loongson-specific exceptions. The extended cause is put in the non-standard CP0.Diag1 register which is CP0 Register 22 Select 1, called GSCause in Loongson manuals. Inside is an exception code bitfield called GSExcCode, only codes 0 to 6 inclusive are documented (so far, in the Loongson 3A3000 User Manual, Volume 2). During experiments, it was found that some undocumented unprivileged instructions can trigger the also-undocumented GSExcCode 8 on Loongson 3A4000. Processor state is not corrupted, but we cannot continue without further knowledge, and Loongson is not providing that information as of this writing. So we send SIGILL on seeing this exception code to thwart easy local DoS attacks. Other exception codes are made fatal, partly because of insufficient knowledge, also partly because they are not as easily reproduced. None of them are encountered in the wild with upstream kernels and userspace so far. Some older cores (Loongson-3A1000 and Loongson-3B1500) have ExcCode 16 too, but the semantic is equivalent to GSExcCode 0. Because the respective manuals did not mention the CP0.Diag1 register or its read behavior, these cores are not covered in this patch, as MFC0 from non-existent CP0 registers is UNDEFINED according to the MIPS architecture spec. Reviewed-by: Huacai Chen <chenhc@lemote.com> Signed-off-by: WANG Xuerui <git@xen0n.name> Cc: Huacai Chen <chenhc@lemote.com> Cc: Jiaxun Yang <jiaxun.yang@flygoat.com> Cc: Tiezhu Yang <yangtiezhu@loongson.cn> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de> |
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| alpha | ||
| arc | ||
| arm | ||
| arm64 | ||
| c6x | ||
| csky | ||
| h8300 | ||
| hexagon | ||
| ia64 | ||
| m68k | ||
| microblaze | ||
| mips | ||
| nds32 | ||
| nios2 | ||
| openrisc | ||
| parisc | ||
| powerpc | ||
| riscv | ||
| s390 | ||
| sh | ||
| sparc | ||
| um | ||
| unicore32 | ||
| x86 | ||
| xtensa | ||
| .gitignore | ||
| Kconfig | ||