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x86: Add support for SW-switched segment-based protection domains

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This patch extends the protection domain framework with a third plugin
that is a hybrid of the previous two.  The hardware task switching
mechanism has a strictly-defined format for TSS data structures that
causes more space to be consumed than would otherwise be required.
This patch defines a smaller data structure that is allocated for each
protection domain, only requiring 32 bytes instead of 128 bytes.  It
uses the same multi-segment memory layout as the TSS-based plugin and
leaves paging disabled.  However, it uses a similar mechanism as the
paging plugin to perform system call dispatches and returns.

For additional information, please refer to cpu/x86/mm/README.md.
This commit is contained in:
Michael LeMay 2015-08-07 11:51:04 -07:00
parent 4cdb7ba9b6
commit e0aefd11d9
13 changed files with 335 additions and 38 deletions
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6
cpu/x86/mm/stacks.h
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@ -61,6 +61,12 @@
#else
#define STACKS_SIZE_EXC 256
#endif
#elif X86_CONF_PROT_DOMAINS == X86_CONF_PROT_DOMAINS__SWSEG
#ifdef __clang__
#define STACKS_SIZE_EXC 512
#else
#define STACKS_SIZE_EXC 256
#endif
#elif X86_CONF_PROT_DOMAINS == X86_CONF_PROT_DOMAINS__TSS
/**
* This should be large enough to execute the exception handler with the