fridtjof/qemu-cr16
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

target/ppc/cpu_init: Simplify the setup of the TLBxCFG SPR registers

Browse source 
The next commit is going to remove init_proc_e200(), which is one of
the two calling sites of register_BookE206_sprs(). This causes recent
versions of GCC to inline the register_BookE206_sprs() function into
the other only remaining calling site, init_proc_e500(), which in
turn causes some false-positives compiler warnings:

 In file included from ../../devel/qemu/target/ppc/cpu_init.c:46:
 In function ‘register_BookE206_sprs’,
     inlined from ‘init_proc_e500’ at ../../devel/qemu/target/ppc/cpu_init.c:2910:5:
 ../../devel/qemu/target/ppc/cpu_init.c:897:29: error:
  array subscript 3 is outside array bounds of ‘uint32_t[2]’ {aka ‘unsigned int[2]’}
  [-Werror=array-bounds=]
   897 |                      tlbncfg[3]);
       |                      ~~~~~~~^~~
 ../../devel/qemu/target/ppc/spr_common.h:61:39: note: in definition of macro ‘spr_register_kvm_hv’
    61 |                   KVM_ARG(one_reg_id) initial_value)
       |                                       ^~~~~~~~~~~~~
 ../../devel/qemu/target/ppc/spr_common.h:77:5: note: in expansion of macro ‘spr_register_kvm’
    77 |     spr_register_kvm(env, num, name, uea_read, uea_write,                    \
       |     ^~~~~~~~~~~~~~~~
 ../../devel/qemu/target/ppc/cpu_init.c:894:9: note: in expansion of macro ‘spr_register’
   894 |         spr_register(env, SPR_BOOKE_TLB3CFG, "TLB3CFG",
       |         ^~~~~~~~~~~~
 ../../devel/qemu/target/ppc/cpu_init.c: In function ‘init_proc_e500’:
 ../../devel/qemu/target/ppc/cpu_init.c:2809:14: note: at offset 12 into object ‘tlbncfg’ of size 8
  2809 |     uint32_t tlbncfg[2];
       |              ^~~~~~~
 cc1: all warnings being treated as errors

init_proc_e500() only defines "uint32_t tlbncfg[2];", but it is OK since
it also sets "env->nb_ways = 2", so the code that GCC warns about in
register_BookE206_sprs() is never reached. Unfortunately, GCC is not smart
enough to see this, so it emits these warnings.

To fix it, let's simplify the code in register_BookE206_sprs() a little
bit to set up the SPRs in a loop, so we don't reference the tlbncfg[3]
entry directly anymore.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Chinmay Rath <rathc@linux.ibm.com>
Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Link: https://lore.kernel.org/r/20251024065726.738005-2-thuth@redhat.com
Message-ID: <20251024065726.738005-2-thuth@redhat.com>
This commit is contained in:
Thomas Huth 2025-10-24 08:57:25 +02:00 • committed by Harsh Prateek Bora
parent 2a62bbf4ed
commit 14e4390a32
No known key found for this signature in database
GPG key ID: 4544E994F9D68FBB
1 changed files with 12 additions and 26 deletions
Download patch file Download diff file Expand all files Collapse all files

38
target/ppc/cpu_init.c
View file

@ -850,6 +850,13 @@ static void register_BookE206_sprs(CPUPPCState *env, uint32_t mas_mask,
SPR_BOOKE_MAS0, SPR_BOOKE_MAS1, SPR_BOOKE_MAS2, SPR_BOOKE_MAS3,
SPR_BOOKE_MAS4, SPR_BOOKE_MAS5, SPR_BOOKE_MAS6, SPR_BOOKE_MAS7,
};
const char *tlbcfg_names[4] = {
"TLB0CFG", "TLB1CFG", "TLB2CFG", "TLB3CFG",
};
const int tlbcfg_sprn[4] = {
SPR_BOOKE_TLB0CFG, SPR_BOOKE_TLB1CFG,
SPR_BOOKE_TLB2CFG, SPR_BOOKE_TLB3CFG,
};
int i;
/* TLB assist registers */
@ -889,34 +896,13 @@ static void register_BookE206_sprs(CPUPPCState *env, uint32_t mas_mask,
SPR_NOACCESS, SPR_NOACCESS,
&spr_read_generic, SPR_NOACCESS,
mmucfg);
switch (env->nb_ways) {
case 4:
spr_register(env, SPR_BOOKE_TLB3CFG, "TLB3CFG",
assert(env->nb_ways <= ARRAY_SIZE(tlbcfg_names));
for (i = 0; i < env->nb_ways; i++) {
spr_register(env, tlbcfg_sprn[i], tlbcfg_names[i],
SPR_NOACCESS, SPR_NOACCESS,
&spr_read_generic, SPR_NOACCESS,
tlbncfg[3]);
/* Fallthru */
case 3:
spr_register(env, SPR_BOOKE_TLB2CFG, "TLB2CFG",
SPR_NOACCESS, SPR_NOACCESS,
&spr_read_generic, SPR_NOACCESS,
tlbncfg[2]);
/* Fallthru */
case 2:
spr_register(env, SPR_BOOKE_TLB1CFG, "TLB1CFG",
SPR_NOACCESS, SPR_NOACCESS,
&spr_read_generic, SPR_NOACCESS,
tlbncfg[1]);
/* Fallthru */
case 1:
spr_register(env, SPR_BOOKE_TLB0CFG, "TLB0CFG",
SPR_NOACCESS, SPR_NOACCESS,
&spr_read_generic, SPR_NOACCESS,
tlbncfg[0]);
/* Fallthru */
case 0:
default:
break;
tlbncfg[i]);
}
#endif
}