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| author | Carlos O'Donell <carlos@parisc-linux.org> | 2005-11-17 16:32:46 -0500 |
|---|---|---|
| committer | Kyle McMartin <kyle@parisc-linux.org> | 2005-11-17 16:32:46 -0500 |
| commit | aa0eecb07f27bea25a7cbe4150822be72493e574 (patch) | |
| tree | 59dc123caeffcc340ea0b6c90c9ff33de191b127 /arch/parisc/kernel | |
| parent | 75be99a8c597aaebf82802109cdfd1249eea951e (diff) | |
| download | linux-aa0eecb07f27bea25a7cbe4150822be72493e574.tar.gz | |
[PARISC] Document some register usages in assembly files
Document clobbers and args in entry.S and syscall.S. entry.S: Add comment to indicate that cr27 may recycle and EDEADLOCK detection is not 100% correct. Since this is only enabled when using ENABLE_LWS_DEBUG, the user is warned by the comment. Signed-off-by: Carlos O'Donell <carlos@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
Diffstat (limited to 'arch/parisc/kernel')
| -rw-r--r-- | arch/parisc/kernel/entry.S | 1 | ||||
| -rw-r--r-- | arch/parisc/kernel/syscall.S | 3 |
2 files changed, 3 insertions, 1 deletions
diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S index c7e66ee5b083..9af4b22a6d77 100644 --- a/arch/parisc/kernel/entry.S +++ b/arch/parisc/kernel/entry.S @@ -1846,6 +1846,7 @@ sys_clone_wrapper: ldo -16(%r30),%r29 /* Reference param save area */ #endif + /* WARNING - Clobbers r19 and r21, userspace must save these! */ STREG %r2,PT_GR19(%r1) /* save for child */ STREG %r30,PT_GR21(%r1) BL sys_clone,%r2 diff --git a/arch/parisc/kernel/syscall.S b/arch/parisc/kernel/syscall.S index b29b76b42bb7..d66163492890 100644 --- a/arch/parisc/kernel/syscall.S +++ b/arch/parisc/kernel/syscall.S @@ -164,7 +164,7 @@ linux_gateway_entry: #endif STREG %r2, TASK_PT_GR30(%r1) /* ... and save it */ - STREG %r20, TASK_PT_GR20(%r1) + STREG %r20, TASK_PT_GR20(%r1) /* Syscall number */ STREG %r21, TASK_PT_GR21(%r1) STREG %r22, TASK_PT_GR22(%r1) STREG %r23, TASK_PT_GR23(%r1) /* 4th argument */ @@ -527,6 +527,7 @@ lws_compare_and_swap: We *must* giveup this call and fail. */ ldw 4(%sr2,%r20), %r28 /* Load thread register */ + /* WARNING: If cr27 cycles to the same value we have problems */ mfctl %cr27, %r21 /* Get current thread register */ cmpb,<>,n %r21, %r28, cas_lock /* Called recursive? */ b lws_exit /* Return error! */ |