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target/ppc: initialize 'val' union in kvm_get_one_spr()

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Valgrind isn't convinced that we are initializing the values we assign
to env->spr[spr] because it doesn't understand that the 'val' union is
being written by the kvm_vcpu_ioctl() that follows (via struct
kvm_one_reg).

This results in Valgrind complaining about uninitialized values every
time we use env->spr in a conditional, like this instance:

==707578== Thread 1:
==707578== Conditional jump or move depends on uninitialised value(s)
==707578==    at 0xA10A40: hreg_compute_hflags_value (helper_regs.c:106)
==707578==    by 0xA10C9F: hreg_compute_hflags (helper_regs.c:173)
==707578==    by 0xA110F7: hreg_store_msr (helper_regs.c:262)
==707578==    by 0xA051A3: ppc_cpu_reset (cpu_init.c:7168)
==707578==    by 0xD4730F: device_transitional_reset (qdev.c:799)
==707578==    by 0xD4A11B: resettable_phase_hold (resettable.c:182)
==707578==    by 0xD49A77: resettable_assert_reset (resettable.c:60)
==707578==    by 0xD4994B: resettable_reset (resettable.c:45)
==707578==    by 0xD458BB: device_cold_reset (qdev.c:296)
==707578==    by 0x48FBC7: cpu_reset (cpu-common.c:114)
==707578==    by 0x97B5EB: spapr_reset_vcpu (spapr_cpu_core.c:38)
==707578==    by 0x97BABB: spapr_cpu_core_reset (spapr_cpu_core.c:209)
==707578==  Uninitialised value was created by a stack allocation
==707578==    at 0xB11F08: kvm_get_one_spr (kvm.c:543)

Initializing 'val' has no impact in the logic and makes Valgrind output
more bearable.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Message-Id: <20220331001717.616938-2-danielhb413@gmail.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
This commit is contained in:
Daniel Henrique Barboza 2022-03-30 21:17:14 -03:00
parent e91b899411
commit 942069e0d2
1 changed files with 2 additions and 1 deletions
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3
target/ppc/kvm.c
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@ -542,10 +542,11 @@ static void kvm_get_one_spr(CPUState *cs, uint64_t id, int spr)
{
PowerPCCPU *cpu = POWERPC_CPU(cs);
CPUPPCState *env = &cpu->env;
/* Init 'val' to avoid "uninitialised value" Valgrind warnings */
union {
uint32_t u32;
uint64_t u64;
} val;
} val = { };
struct kvm_one_reg reg = {
.id = id,
.addr = (uintptr_t) &val,