Commit graph

1308 commits

Author SHA1 Message Date
Frans Kaashoek a42b7d5dbb Simplify freeing page table 2018-10-02 08:12:01 -04:00
Frans Kaashoek 155c13b7f8 Avoid repition in walkpgdir 2018-10-02 07:37:49 -04:00
Frans Kaashoek 572e106e6f x 2018-09-29 09:05:25 -04:00
Frans Kaashoek 3bfcaeaf01 Make sysexit and trapret paths the same, so that forkret can return through
either path.  This helped tracking down a bug: use 144 instead of 32 to find cs
in trapframe so that gs is correctly saved and restored.

For good measure update linker script, because newer versions of GCC sometimes
places symbols passed end.
2018-09-29 08:34:41 -04:00
Frans Kaashoek 322990649b x 2018-09-29 08:29:34 -04:00
Frans Kaashoek ab0db651af Checkpoint port of xv6 to x86-64. Passed usertests on 2 processors a few times.
The x86-64 doesn't just add two levels to page tables to support 64 bit
addresses, but is a different processor. For example, calling conventions,
system calls, and segmentation are different from 32-bit x86. Segmentation is
basically gone, but gs/fs in combination with MSRs can be used to hold a
per-core pointer. In general, x86-64 is more straightforward than 32-bit
x86. The port uses code from sv6 and the xv6 "rsc-amd64" branch.

A summary of the changes is as follows:

- Booting: switch to grub instead of xv6's bootloader (pass -kernel to qemu),
because xv6's boot loader doesn't understand 64bit ELF files.  And, we don't
care anymore about booting.

- Makefile: use -m64 instead of -m32 flag for gcc, delete boot loader, xv6.img,
bochs, and memfs. For now dont' use -O2, since usertests with -O2 is bigger than
MAXFILE!

- Update gdb.tmpl to be for i386 or x86-64

- Console/printf: use stdarg.h and treat 64-bit addresses different from ints
  (32-bit)

- Update elfhdr to be 64 bit

- entry.S/entryother.S: add code to switch to 64-bit mode: build a simple page
table in 32-bit mode before switching to 64-bit mode, share code for entering
boot processor and APs, and tweak boot gdt.  The boot gdt is the gdt that the
kernel proper also uses. (In 64-bit mode, the gdt/segmentation and task state
mostly disappear.)

- exec.c: fix passing argv (64-bit now instead of 32-bit).

- initcode.c: use syscall instead of int.

- kernel.ld: load kernel very high, in top terabyte.  64 bits is a lot of
address space!

- proc.c: initial return is through new syscall path instead of trapret.

- proc.h: update struct cpu to have some scratch space since syscall saves less
state than int, update struct context to reflect x86-64 calling conventions.

- swtch: simplify for x86-64 calling conventions.

- syscall: add fetcharg to handle x86-64 calling convetions (6 arguments are
passed through registers), and fetchaddr to read a 64-bit value from user space.

- sysfile: update to handle pointers from user space (e.g., sys_exec), which are
64 bits.

- trap.c: no special trap vector for sys calls, because x86-64 has a different
plan for system calls.

- trapasm: one plan for syscalls and one plan for traps (interrupt and
exceptions). On x86-64, the kernel is responsible for switching user/kernel
stacks. To do, xv6 keeps some scratch space in the cpu structure, and uses MSR
GS_KERN_BASE to point to the core's cpu structure (using swapgs).

- types.h: add uint64, and change pde_t to uint64

- usertests: exit() when fork fails, which helped in tracking down one of the
bugs in the switch from 32-bit to 64-bit

- vectors: update to make them 64 bits

- vm.c: use bootgdt in kernel too, program MSRs for syscalls and core-local
state (for swapgs), walk 4 levels in walkpgdir, add DEVSPACETOP, use task
segment to set kernel stack for interrupts (but simpler than in 32-bit mode),
add an extra argument to freevm (size of user part of address space) to avoid
checking all entries till KERNBASE (there are MANY TB before the top 1TB).

- x86: update trapframe to have 64-bit entries, which is what the processor
pushes on syscalls and traps.  simplify lgdt and lidt, using struct desctr,
which needs the gcc directives packed and aligned.

TODO:
- use int32 instead of int?
- simplify curproc(). xv6 has per-cpu state again, but this time it must have it.
- avoid repetition in walkpgdir
- fix validateint() in usertests.c
- fix bugs (e.g., observed one a case of entering kernel with invalid gs or proc
2018-09-23 08:35:30 -04:00
Frans Kaashoek b818915f79 Update name
Use generic 6.828 url (without year)
2018-09-02 08:33:55 -04:00
Frans Kaashoek 308a3b88c9 thanks tyfkda 2018-08-31 09:21:19 -04:00
Frans Kaashoek 343255189e thanks Wolfgang Keller 2018-08-31 08:41:23 -04:00
Frans Kaashoek 80f70c46df x 2018-08-30 16:20:16 -04:00
Frans Kaashoek 1d19081efb Allow holding to be called with interrupts enabled (for Mark Morrissey). 2018-08-30 16:14:34 -04:00
Frans Kaashoek 2c73068e82 Delete a patch
Adjust typesetting of code
2018-08-30 15:45:16 -04:00
Frans Kaashoek e559fd2c5a x 2018-08-30 14:47:07 -04:00
Frans Kaashoek f30488793b x 2018-08-30 14:16:29 -04:00
Frans Kaashoek 76d4005f9e thanks mtasm 2018-08-30 14:10:27 -04:00
Frans Kaashoek 6710e5589d thanks wxdao 2018-08-30 13:48:47 -04:00
Frans Kaashoek 96e4e2f4d1 thanks eyalz800 2018-08-30 13:46:48 -04:00
Frans Kaashoek 8f63beaacb vectors.pl is executable and asks shell for perl 2018-08-30 13:36:07 -04:00
Frans Kaashoek 171c2cc6b8 thanks mataness 2018-08-30 13:30:50 -04:00
Frans Kaashoek 26108a3b99 thanks tyfkda 2018-08-30 13:27:57 -04:00
Frans Kaashoek 7f3528bcb3 x 2018-08-30 13:25:54 -04:00
Frans Kaashoek 210a0f0b30 Remove unused flags (thanks Wolfgang Keller) 2018-08-30 13:14:01 -04:00
Frans Kaashoek b2ca8e3e23 x 2018-08-30 13:09:03 -04:00
Frans Kaashoek 960a94fb87 x 2018-08-30 12:12:16 -04:00
Frans Kaashoek 0b86d03767 Because sleeplocks replaced B_BUSY the holding test can
be more specific (thanks Mark Morrissey)
2018-08-30 11:57:46 -04:00
Frans Kaashoek 0b6f4c08b9 x 2018-08-30 11:42:10 -04:00
Robert Morris 0754d21c86 stricter log consumption by write() 2017-10-24 08:49:31 -04:00
Robert Morris 1ab23170a1 improve swtch comment 2017-10-08 07:12:31 -04:00
Robert Morris 4638cabf8c fix runoff complaints about pagination and long lines 2017-08-29 14:11:59 -04:00
Frans Kaashoek 164f4bae54 thx 2017-08-10 07:09:53 -04:00
Frans Kaashoek 3e392c7288 Update comment to reflect xv6 doesn't have per-cpu segments anymore 2017-08-09 15:21:42 -04:00
Robert Morris 6389d9d410 nothing much 2017-08-09 14:16:55 -04:00
Frans Kaashoek 4f14d8d1e5 Commit to running on an SMP (perhaps with only 1 core). Remove most code
from picirq.c and remove timer.c completely.  Update runoff.list.
2017-08-09 07:44:51 -04:00
Robert Morris 70705966ad comment fixes 2017-08-09 06:54:45 -04:00
Frans Kaashoek da3b931ddb Thanks Anton Burtsev <aburtsev@uci.edu> 2017-08-08 19:42:51 -04:00
Robert Morris a4ee6f7de3 fix iput() to more obviously avoid deadlock 2017-08-08 14:19:54 -04:00
Robert Morris 1c7aa96005 a little more lock documentation 2017-08-08 14:12:25 -04:00
Robert Morris 70d912b332 protect ip->valid and ip->nlink with sleep lock in iput() 2017-08-08 13:48:48 -04:00
Robert Morris 3375df5061 change ip->flags&I_VALID to ip->valid 2017-08-08 13:34:13 -04:00
Robert Morris 14270288b7 Merge branch 'master' of g.csail.mit.edu:xv6-dev 2017-08-08 13:27:06 -04:00
Robert Morris aba8423c4a frans' fixes to iput() 2017-08-08 13:26:57 -04:00
Robert Morris 9cec455b17 fs comment nits 2017-08-08 13:24:38 -04:00
Frans Kaashoek 825ce074b1 Remove some debugging statements 2017-08-07 15:15:18 -04:00
Frans Kaashoek 61cb32aa9b Merge branch 'nogs' 2017-08-07 14:35:05 -04:00
Frans Kaashoek 5cbccef811 Merge branch 'patch-1' of https://github.com/aliceinwire/xv6-public 2017-08-07 13:44:03 -04:00
Frans Kaashoek 0249311675 Merge branch 'patch-1' of https://github.com/Saarett/xv6-public 2017-08-07 13:29:11 -04:00
Grant Wu 61f26e3c97 Fix typo in dirlookup 2017-04-26 19:56:51 -07:00
Alice Ferrazzi 1fb2ea8890 Update LICENSE
updated copyright year
2017-02-27 13:12:59 +09:00
Saarett 03b3086327 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.
2017-02-05 12:44:56 +02:00
Frans Kaashoek c9fa90f7e5 A tiny bit of clean up (e.g., move code searching cpu array from lapic.c into
mycpu() in proc.c.
2017-02-01 20:36:41 -05:00