[ CCed Jakub ] >>> Boot time fixup v1.6. 4/Mar/98 Jakub Jelinek (jj@xxxxxxxxxxxxxx). >>> Patching kernel for srmmu[Fujitsu TurboSparc]/iommu >>> Fixup i f029ddfc doesn't refer to a valid instruction at >>> f00de648[95eea000] >>> halt, power off > I put the broken image up at http://landley.net/sparc-image for the > moment, but if you build 3.1 with the attached .config and the toolchain > mentioned last time, it should reproduce for you. It's 100% reliable > for me... Nice! With this config it breaks for me on your and mine toolchains. The offending function is ext4_kvmalloc (and similar ext4_kvzalloc). The usual relocation in sparc looks like a pair of instructions loading two pats of address in 2 instructions: Like that: > sethi %hi(ext4_fill_super), %o4 !, tmp113 > or %o4, %lo(ext4_fill_super), %o4 ! tmp113,, tmp28 In our case relocatable symbol sits in tail call, so %lo part is in "unusual" RESTORE instruction: > ext4_kvmalloc: ... > sethi %hi(___i_page_kernel), %i2 !, tmp112 > call __vmalloc, 0 ! > restore %i2, %lo(___i_page_kernel), %o2 ! tmp112,, ... David: is this code correct? Or it's a compiler bug? I am sparc32 newbie. (C source and asm sources of function are in [1]) I think this kind of code is generated only in -Os. So to workaround it I tried this hack: > --- a/fs/ext4/super.c > +++ b/fs/ext4/super.c > ret = kmalloc(size, flags); > if (!ret) > ret = __vmalloc(size, flags, PAGE_KERNEL); > + > + asm __volatile__("nop":::"memory"); > + > return ret; > } (for both ext4_kvmalloc / ext4_kvzalloc. Attached workaround as a patch.) It forces compiler to geterate "usual" pattern for relocation. I think of 2 solutions: 1. trying to fix sparc/boot/btfixupprep.c and arch/sparc/mm/btfixup.c to distinct HI22 and LO10 relocations as different ones. Right now they are merged into one 'i' type and rely on instruction heuristics to fix it. 2. Add a hack to arch/sparc/mm/btfixup.c to recognize restore instruction as well Any others? Hope that helps. [1]: void *ext4_kvmalloc(size_t size, gfp_t flags) { void *ret; ret = kmalloc(size, flags); if (!ret) ret = __vmalloc(size, flags, PAGE_KERNEL); return ret; } .global ext4_kvmalloc .type ext4_kvmalloc, #function .proc 0120 ext4_kvmalloc: save %sp, -96, %sp ! mov %i0, %o0 ! size, call __kmalloc, 0 !, mov %i1, %o1 ! flags, cmp %o0, 0 ! ret, bne .LL274 ! sethi %hi(___i_page_kernel), %i2 !, tmp112 call __vmalloc, 0 ! restore %i2, %lo(___i_page_kernel), %o2 ! tmp112,, .LL274: jmp %i7+8 restore %g0, %o0, %o0 ! ret, .size ext4_kvmalloc, .-ext4_kvmalloc -- Sergei
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 44d0c8d..570d45e 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -117,6 +117,7 @@ void *ext4_kvmalloc(size_t size, gfp_t flags) ret = kmalloc(size, flags); if (!ret) ret = __vmalloc(size, flags, PAGE_KERNEL); + mb(); /* hack to pessimize code */ return ret; } @@ -127,6 +128,7 @@ void *ext4_kvzalloc(size_t size, gfp_t flags) ret = kzalloc(size, flags); if (!ret) ret = __vmalloc(size, flags | __GFP_ZERO, PAGE_KERNEL); + mb(); /* hack to pessimize code */ return ret; }
Attachment:
signature.asc
Description: PGP signature
