Re: [Qemu-devel] [RFC PATCH for 4.1?] target/ppc: move opcode decode tables to PowerPCCPU

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Jul 16, 2019 at 01:13:52PM +0100, Alex Bennée wrote:
> The opcode decode tables aren't really part of the CPUPPCState but an
> internal implementation detail for the translator. This can cause
> problems with memcpy in cpu_copy as any table created during
> ppc_cpu_realize get written over causing a memory leak. To avoid this
> move the tables into PowerPCCPU which is better suited to hold
> internal implementation details.
> 
> Attempts to fix: https://bugs.launchpad.net/qemu/+bug/1836558
> Cc: 1836558@bugs.launchpad.net
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

I've applied this now to ppc-for-4.2.  If there's an argument for
including it in 4.1 during hard freeze, you'll need to spell it out
for me.

> ---
>  target/ppc/cpu.h                |  8 ++++----
>  target/ppc/translate.c          |  3 ++-
>  target/ppc/translate_init.inc.c | 16 +++++++---------
>  3 files changed, 13 insertions(+), 14 deletions(-)
> 
> diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
> index c9beba2a5c0..10e34b69b75 100644
> --- a/target/ppc/cpu.h
> +++ b/target/ppc/cpu.h
> @@ -1104,10 +1104,6 @@ struct CPUPPCState {
>      bool resume_as_sreset;
>  #endif
>  
> -    /* Those resources are used only during code translation */
> -    /* opcode handlers */
> -    opc_handler_t *opcodes[PPC_CPU_OPCODES_LEN];
> -
>      /* Those resources are used only in QEMU core */
>      target_ulong hflags;      /* hflags is a MSR & HFLAGS_MASK         */
>      target_ulong hflags_nmsr; /* specific hflags, not coming from MSR */
> @@ -1191,6 +1187,10 @@ struct PowerPCCPU {
>      int32_t node_id; /* NUMA node this CPU belongs to */
>      PPCHash64Options *hash64_opts;
>  
> +    /* Those resources are used only during code translation */
> +    /* opcode handlers */
> +    opc_handler_t *opcodes[PPC_CPU_OPCODES_LEN];
> +
>      /* Fields related to migration compatibility hacks */
>      bool pre_2_8_migration;
>      target_ulong mig_msr_mask;
> diff --git a/target/ppc/translate.c b/target/ppc/translate.c
> index 4a5de280365..c0faab8a824 100644
> --- a/target/ppc/translate.c
> +++ b/target/ppc/translate.c
> @@ -7857,6 +7857,7 @@ static bool ppc_tr_breakpoint_check(DisasContextBase *dcbase, CPUState *cs,
>  static void ppc_tr_translate_insn(DisasContextBase *dcbase, CPUState *cs)
>  {
>      DisasContext *ctx = container_of(dcbase, DisasContext, base);
> +    PowerPCCPU *cpu = POWERPC_CPU(cs);
>      CPUPPCState *env = cs->env_ptr;
>      opc_handler_t **table, *handler;
>  
> @@ -7874,7 +7875,7 @@ static void ppc_tr_translate_insn(DisasContextBase *dcbase, CPUState *cs)
>                opc3(ctx->opcode), opc4(ctx->opcode),
>                ctx->le_mode ? "little" : "big");
>      ctx->base.pc_next += 4;
> -    table = env->opcodes;
> +    table = cpu->opcodes;
>      handler = table[opc1(ctx->opcode)];
>      if (is_indirect_opcode(handler)) {
>          table = ind_table(handler);
> diff --git a/target/ppc/translate_init.inc.c b/target/ppc/translate_init.inc.c
> index 86fc8f2e316..9cd2033bb92 100644
> --- a/target/ppc/translate_init.inc.c
> +++ b/target/ppc/translate_init.inc.c
> @@ -9440,14 +9440,13 @@ static void fix_opcode_tables(opc_handler_t **ppc_opcodes)
>  static void create_ppc_opcodes(PowerPCCPU *cpu, Error **errp)
>  {
>      PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
> -    CPUPPCState *env = &cpu->env;
>      opcode_t *opc;
>  
> -    fill_new_table(env->opcodes, PPC_CPU_OPCODES_LEN);
> +    fill_new_table(cpu->opcodes, PPC_CPU_OPCODES_LEN);
>      for (opc = opcodes; opc < &opcodes[ARRAY_SIZE(opcodes)]; opc++) {
>          if (((opc->handler.type & pcc->insns_flags) != 0) ||
>              ((opc->handler.type2 & pcc->insns_flags2) != 0)) {
> -            if (register_insn(env->opcodes, opc) < 0) {
> +            if (register_insn(cpu->opcodes, opc) < 0) {
>                  error_setg(errp, "ERROR initializing PowerPC instruction "
>                             "0x%02x 0x%02x 0x%02x", opc->opc1, opc->opc2,
>                             opc->opc3);
> @@ -9455,7 +9454,7 @@ static void create_ppc_opcodes(PowerPCCPU *cpu, Error **errp)
>              }
>          }
>      }
> -    fix_opcode_tables(env->opcodes);
> +    fix_opcode_tables(cpu->opcodes);
>      fflush(stdout);
>      fflush(stderr);
>  }
> @@ -10023,7 +10022,6 @@ static void ppc_cpu_unrealize(DeviceState *dev, Error **errp)
>  {
>      PowerPCCPU *cpu = POWERPC_CPU(dev);
>      PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
> -    CPUPPCState *env = &cpu->env;
>      Error *local_err = NULL;
>      opc_handler_t **table, **table_2;
>      int i, j, k;
> @@ -10035,11 +10033,11 @@ static void ppc_cpu_unrealize(DeviceState *dev, Error **errp)
>      }
>  
>      for (i = 0; i < PPC_CPU_OPCODES_LEN; i++) {
> -        if (env->opcodes[i] == &invalid_handler) {
> +        if (cpu->opcodes[i] == &invalid_handler) {
>              continue;
>          }
> -        if (is_indirect_opcode(env->opcodes[i])) {
> -            table = ind_table(env->opcodes[i]);
> +        if (is_indirect_opcode(cpu->opcodes[i])) {
> +            table = ind_table(cpu->opcodes[i]);
>              for (j = 0; j < PPC_CPU_INDIRECT_OPCODES_LEN; j++) {
>                  if (table[j] == &invalid_handler) {
>                      continue;
> @@ -10057,7 +10055,7 @@ static void ppc_cpu_unrealize(DeviceState *dev, Error **errp)
>                                               ~PPC_INDIRECT));
>                  }
>              }
> -            g_free((opc_handler_t *)((uintptr_t)env->opcodes[i] &
> +            g_free((opc_handler_t *)((uintptr_t)cpu->opcodes[i] &
>                  ~PPC_INDIRECT));
>          }
>      }

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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