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| author | James Bottomley <jejb@parisc-linux.org> | 2005-10-21 22:53:26 -0400 |
|---|---|---|
| committer | Kyle McMartin <kyle@parisc-linux.org> | 2005-10-21 22:53:26 -0400 |
| commit | 618febd6784054eea928d712b7e564558a7cefd5 (patch) | |
| tree | 13a60c377dc5a17f44e9b3b227e5996e0ba7e5a4 /include/asm-parisc | |
| parent | b2450cc1b7ce07d73545ece32db50197d649e230 (diff) | |
| download | lwn-618febd6784054eea928d712b7e564558a7cefd5.tar.gz lwn-618febd6784054eea928d712b7e564558a7cefd5.zip | |
[PARISC] Fix the alloc_slabmgmt panic
Fix the alloc_slabmgmt panic
Hopefully this should also fix a lot of other intermittent kernel bugs.
The problem has been around since 2.6.9-rc2-pa6 when we allowed
floating point registers to be used in kernel code. The essence of
the problem is that gcc prefers to use floating point for integer
divides and multiples. Further, it can rely on the values in the no
clobber fp regs being correct across a function call. Unfortunately,
our task switch function only saves the integer no clobber registers,
not the fp ones, so if gcc makes a function call to any function in
the kernel which could sleep, the values it is relying on in any no
clobber floating point register may be lost. In the case of
alloc_slabmgmt, the value of the page offset is being stored in %fr12
across a call to kmem_getpages(), which sleeps if no pages are
available. Thus, the offset can be trashed and the slab code can end
up with a completely bogus address leading to corruption.
Kudos to Randolph who came up with the program to trip this problem at
will and thus allowed it to be tracked and fixed.
Signed-off-by: James Bottomley <jejb@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
Diffstat (limited to 'include/asm-parisc')
| -rw-r--r-- | include/asm-parisc/assembly.h | 40 |
1 files changed, 34 insertions, 6 deletions
diff --git a/include/asm-parisc/assembly.h b/include/asm-parisc/assembly.h index b24a99e3ef9c..fb8bc7c16e0e 100644 --- a/include/asm-parisc/assembly.h +++ b/include/asm-parisc/assembly.h @@ -21,6 +21,7 @@ #ifndef _PARISC_ASSEMBLY_H #define _PARISC_ASSEMBLY_H +#define CALLEE_FLOAT_FRAME_SIZE 80 #ifdef __LP64__ #define LDREG ldd #define STREG std @@ -30,7 +31,7 @@ #define SHRREG shrd #define RP_OFFSET 16 #define FRAME_SIZE 128 -#define CALLEE_SAVE_FRAME_SIZE 144 +#define CALLEE_REG_FRAME_SIZE 144 #else #define LDREG ldw #define STREG stw @@ -40,8 +41,9 @@ #define SHRREG shr #define RP_OFFSET 20 #define FRAME_SIZE 64 -#define CALLEE_SAVE_FRAME_SIZE 128 +#define CALLEE_REG_FRAME_SIZE 128 #endif +#define CALLEE_SAVE_FRAME_SIZE (CALLEE_REG_FRAME_SIZE + CALLEE_FLOAT_FRAME_SIZE) #ifdef CONFIG_PA20 #define BL b,l @@ -300,9 +302,35 @@ fldd,mb -8(\regs), %fr0 .endm + .macro callee_save_float + fstd,ma %fr12, 8(%r30) + fstd,ma %fr13, 8(%r30) + fstd,ma %fr14, 8(%r30) + fstd,ma %fr15, 8(%r30) + fstd,ma %fr16, 8(%r30) + fstd,ma %fr17, 8(%r30) + fstd,ma %fr18, 8(%r30) + fstd,ma %fr19, 8(%r30) + fstd,ma %fr20, 8(%r30) + fstd,ma %fr21, 8(%r30) + .endm + + .macro callee_rest_float + fldd,mb -8(%r30), %fr21 + fldd,mb -8(%r30), %fr20 + fldd,mb -8(%r30), %fr19 + fldd,mb -8(%r30), %fr18 + fldd,mb -8(%r30), %fr17 + fldd,mb -8(%r30), %fr16 + fldd,mb -8(%r30), %fr15 + fldd,mb -8(%r30), %fr14 + fldd,mb -8(%r30), %fr13 + fldd,mb -8(%r30), %fr12 + .endm + #ifdef __LP64__ .macro callee_save - std,ma %r3, CALLEE_SAVE_FRAME_SIZE(%r30) + std,ma %r3, CALLEE_REG_FRAME_SIZE(%r30) mfctl %cr27, %r3 std %r4, -136(%r30) std %r5, -128(%r30) @@ -340,13 +368,13 @@ ldd -128(%r30), %r5 ldd -136(%r30), %r4 mtctl %r3, %cr27 - ldd,mb -CALLEE_SAVE_FRAME_SIZE(%r30), %r3 + ldd,mb -CALLEE_REG_FRAME_SIZE(%r30), %r3 .endm #else /* ! __LP64__ */ .macro callee_save - stw,ma %r3, CALLEE_SAVE_FRAME_SIZE(%r30) + stw,ma %r3, CALLEE_REG_FRAME_SIZE(%r30) mfctl %cr27, %r3 stw %r4, -124(%r30) stw %r5, -120(%r30) @@ -384,7 +412,7 @@ ldw -120(%r30), %r5 ldw -124(%r30), %r4 mtctl %r3, %cr27 - ldw,mb -CALLEE_SAVE_FRAME_SIZE(%r30), %r3 + ldw,mb -CALLEE_REG_FRAME_SIZE(%r30), %r3 .endm #endif /* ! __LP64__ */ |