From e0037df3852b4b60edbe01f70f4968e4a9fdb272 Mon Sep 17 00:00:00 2001 From: Andrea Shepard Date: Sun, 19 Oct 2008 23:33:03 -0700 Subject: [PATCH] sparc64: Fix race in arch/sparc64/kernel/trampoline.S 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 Signed-off-by: David S. Miller --- arch/sparc64/kernel/trampoline.S | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/arch/sparc64/kernel/trampoline.S b/arch/sparc64/kernel/trampoline.S index 704a3afcfd0..83abd5ae88a 100644 --- a/arch/sparc64/kernel/trampoline.S +++ b/arch/sparc64/kernel/trampoline.S @@ -328,6 +328,12 @@ after_lock_tlb: 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. @@ -337,7 +343,7 @@ after_lock_tlb: 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) @@ -369,10 +375,10 @@ after_lock_tlb: 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 @@ -386,7 +392,11 @@ after_lock_tlb: 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 -- 2.20.1