Messages in this thread Patch in this message | | | Date | Fri, 17 Oct 2008 17:06:35 -0700 | From | Andrea Shepard <> | Subject | [PATCH] Fix race in arch/sparc64/kernel/trampoline.S |
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Make arch/sparc64/kernel/trampoline.S in 2.6.27.1 lock prom_entry_lock when calling the PROM. This prevents a race condition that I observed causing a hang on startup on a 12-CPU E4500.
I am not subscribed to this list, so please CC me on replies.
Signed-off-by: Andrea Shepard <andrea@persephoneslair.org>
diff -Naur linux-2.6.27.1/arch/sparc64/kernel/trampoline.S linux-2.6.27.1.patched/arch/sparc64/kernel/trampoline.S --- linux-2.6.27.1/arch/sparc64/kernel/trampoline.S 2008-10-15 16:02:53.000000000 -0700 +++ linux-2.6.27.1.patched/arch/sparc64/kernel/trampoline.S 2008-10-17 13:17:09.401334338 -0700 @@ -328,6 +328,12 @@ wrpr %g0, 0, %wstate + sethi %hi(prom_entry_lock), %g2 +1: ldstub [%g2 + %lo(prom_entry_lock)], %g1 + membar #StoreLoad | #StoreStore + brnz,pn %g1, 1b + nop + /* As a hack, put &init_thread_union into %g6. * prom_world() loads from here to restore the %asi * register. @@ -337,9 +343,9 @@ sethi %hi(is_sun4v), %o0 lduw [%o0 + %lo(is_sun4v)], %o0 - brz,pt %o0, 1f + brz,pt %o0, 2f nop
TRAP_LOAD_TRAP_BLOCK(%g2, %g3) add %g2, TRAP_PER_CPU_FAULT_INFO, %g2 stxa %g2, [%g0] ASI_SCRATCHPAD @@ -369,10 +375,10 @@ call %o1 add %sp, (2047 + 128), %o0 - ba,pt %xcc, 2f + ba,pt %xcc, 3f nop -1: sethi %hi(sparc64_ttable_tl0), %o0 +2: sethi %hi(sparc64_ttable_tl0), %o0 set prom_set_trap_table_name, %g2 stx %g2, [%sp + 2047 + 128 + 0x00] mov 1, %g2 @@ -386,9 +392,13 @@ call %o1 add %sp, (2047 + 128), %o0 -2: ldx [%l0], %g6 +3: sethi %hi(prom_entry_lock), %g2 + stb %g0, [%g2 + %lo(prom_entry_lock)] + membar #StoreStore | #StoreLoad + + ldx [%l0], %g6 ldx [%g6 + TI_TASK], %g4
mov 1, %g5 sllx %g5, THREAD_SHIFT, %g5 sub %g5, (STACKFRAME_SZ + STACK_BIAS), %g5
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