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target/ppc: Fix QEMU crash with stxsdx

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I've been hitting several QEMU crashes while running a fedora29 ppc64le
guest under TCG. Each time, this would occur several minutes after the
guest reached login:

Fedora 29 (Twenty Nine)
Kernel 4.20.6-200.fc29.ppc64le on an ppc64le (hvc0)

Web console: https://localhost:9090/

localhost login:
tcg/tcg.c:3211: tcg fatal error

This happens because a bug crept up in the gen_stxsdx() helper when it
was converted to use VSR register accessors by commit 8b3b2d75c7
"target/ppc: introduce get_cpu_vsr{l,h}() and set_cpu_vsr{l,h}() helpers
for VSR register access".

The code creates a temporary, passes it directly to gen_qemu_st64_i64()
and then to set_cpu_vrsh()... which looks like this was mistakenly
coded as a load instead of a store.

Reverse the logic: read the VSR to the temporary first and then store
it to memory.

Fixes: 8b3b2d75c7
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <155371035249.2038502.12364252604337688538.stgit@bahia.lan>
Reviewed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Greg Kurz 2019-03-27 19:12:32 +01:00 committed by David Gibson
parent 15d68c5e1d
commit 3e5365b7aa
1 changed files with 1 additions and 1 deletions
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2
target/ppc/translate/vsx-impl.inc.c
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@ -356,8 +356,8 @@ static void gen_##name(DisasContext *ctx) \
gen_set_access_type(ctx, ACCESS_INT); \ gen_set_access_type(ctx, ACCESS_INT); \
EA = tcg_temp_new(); \ EA = tcg_temp_new(); \
gen_addr_reg_index(ctx, EA); \ gen_addr_reg_index(ctx, EA); \
get_cpu_vsrh(t0, xS(ctx->opcode)); \
gen_qemu_##operation(ctx, t0, EA); \ gen_qemu_##operation(ctx, t0, EA); \
set_cpu_vsrh(xS(ctx->opcode), t0); \
tcg_temp_free(EA); \ tcg_temp_free(EA); \
tcg_temp_free_i64(t0); \ tcg_temp_free_i64(t0); \
} }