thanks mataness

fix runoff complaints about pagination and long lines

Free pgdir in setupkvm in case of mappages failure

There is a potential memory leak when mappages() fails inside setupkvm().
A call to freevm() is added in this case so as to reclaim the lost mappi

Free pgdir in setupkvm in case of mappages failure

There is a potential memory leak when mappages() fails inside setupkvm().
A call to freevm() is added in this case so as to reclaim the lost mapping pages.

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Eliminate code for gs trick to track per-cpu state. We rely on lapiccpunum()
to find a per-cpu id with which we locate a cpu's cpu struct.

Read curproc from cpu structure, but be careful because after a schedule event
myproc() points to a different thread.

myproc();
sched();
myproc(); // this proc maybe different than the one

Read curproc from cpu structure, but be careful because after a schedule event
myproc() points to a different thread.

myproc();
sched();
myproc(); // this proc maybe different than the one before sched

Thus, in a function that operates on one thread better to retrieve the
current process once at the start of the function.

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Start of an experiment to remove the use of gs for cpu local variables.

Fix long-standing switchuvm() inconsistency.

switchuvm() is supposed to switch the TSS and page table to the
process p it is passed. Alas, instead of using p to access the
kstack field, it used the

Fix long-standing switchuvm() inconsistency.

switchuvm() is supposed to switch the TSS and page table to the
process p it is passed. Alas, instead of using p to access the
kstack field, it used the global proc. This worked fine because
(a) most uses of switchuvm() pass proc anyway and (b) because in
the schedule, where we call switchuvm with the newly scheduled
process, we actually set the global proc before the call. But I
think it's still a bug, even if it never broke a test case. :-)

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fix possible memory leak in deallocuvm

when a zero PDE is encountered while searching for present PTEs to free,
resume searching at first entry of the next page table instead of the
current entry of

fix possible memory leak in deallocuvm

when a zero PDE is encountered while searching for present PTEs to free,
resume searching at first entry of the next page table instead of the
current entry of the next page table.

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curproc -> proc in a comment

better comment

set iomb to forbid i/o instructions from user space
add to test that they indeed trap in user space
thanks to pablogventura@gmail.com and nwolovick@gmail.com

Remove trailing white space with:
for f in *.{h,c}; do sed -i .sed 's/[[:blank:]]*$//' $f; done
(Thanks to Nicolás Wolovick)

p2v -> P2V

nothing much

tiny clarifications to some gdt code.

shell nits
fix Regehr complaint

Nice layout for a printout of the code

Correct a security bug in copyuvm()

copyuvm() should not allow new copied pages to inherit more
permissions than the original pages.

nits

Runoff still complaints these lines are too long, but it is now ok on printout

Remove unused argument to setupkvm (thanks to Peter Froehlich)

eliminate enter_alloc -- use kalloc for everything

more regular kmap[] and description

Nuke data.S, since we do have a custom linker script.

Oops, dropped a paren