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target/ppc: Move no-execute and guarded page checking into new function 

A pte entry has bit fields which can be used to make a page no-execute or
guarded, if either of these bits are set then an instruction access to this
page will fail. Currently these bits are checked with the pp_prot function
however the ISA specifies that the access authority controlled by the
key-pp value pair should only be checked on an instruction access after
the no-execute and guard bits have already been verified to permit the
access.

Move the no-execute and guard bit checking into a new separate function.
Note that we can remove the check for the no-execute bit in the slb entry
since this check was already performed above when we obtained the slb
entry.

In the event that the no-execute or guard bits are set, an ISI should be
generated with the SRR1_NOEXEC_GUARD (0x10000000) bit set in srr1. Add a
define for this for clarity.

Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
[dwg: Move constants to cpu.h since they're not MMUv3 specific]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Suraj Jitindar Singh 2017-03-01 18:12:54 +11:00 committed by David Gibson
parent 347a5c73ba
commit 07a68f9907
2 changed files with 17 additions and 9 deletions
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1
target/ppc/cpu.h
View File

@ -475,6 +475,7 @@ struct ppc_slb_t {
/* SRR1 error code fields */
#define SRR1_NOEXEC_GUARD 0x10000000
#define SRR1_PROTFAULT 0x08000000
#define SRR1_IAMR 0x00200000

25
target/ppc/mmu-hash64.c
View File

@ -290,6 +290,16 @@ target_ulong helper_load_slb_vsid(CPUPPCState *env, target_ulong rb)
return rt;
}
/* Check No-Execute or Guarded Storage */
static inline int ppc_hash64_pte_noexec_guard(PowerPCCPU *cpu,
ppc_hash_pte64_t pte)
{
/* Exec permissions CANNOT take away read or write permissions */
return (pte.pte1 & HPTE64_R_N) || (pte.pte1 & HPTE64_R_G) ?
PAGE_READ | PAGE_WRITE : PAGE_READ | PAGE_WRITE | PAGE_EXEC;
}
/* Check Basic Storage Protection */
static int ppc_hash64_pte_prot(PowerPCCPU *cpu,
ppc_slb_t *slb, ppc_hash_pte64_t pte)
{
@ -333,12 +343,6 @@ static int ppc_hash64_pte_prot(PowerPCCPU *cpu,
}
}
/* No execute if either noexec or guarded bits set */
if (!(pte.pte1 & HPTE64_R_N) || (pte.pte1 & HPTE64_R_G)
|| (slb->vsid & SLB_VSID_N)) {
prot |= PAGE_EXEC;
}
return prot;
}
@ -696,7 +700,7 @@ int ppc_hash64_handle_mmu_fault(PowerPCCPU *cpu, vaddr eaddr,
unsigned apshift;
hwaddr ptex;
ppc_hash_pte64_t pte;
int pp_prot, amr_prot, prot;
int exec_prot, pp_prot, amr_prot, prot;
uint64_t new_pte1, dsisr;
const int need_prot[] = {PAGE_READ, PAGE_WRITE, PAGE_EXEC};
hwaddr raddr;
@ -803,16 +807,19 @@ skip_slb_search:
/* 5. Check access permissions */
exec_prot = ppc_hash64_pte_noexec_guard(cpu, pte);
pp_prot = ppc_hash64_pte_prot(cpu, slb, pte);
amr_prot = ppc_hash64_amr_prot(cpu, pte);
prot = pp_prot & amr_prot;
prot = exec_prot & pp_prot & amr_prot;
if ((need_prot[rwx] & ~prot) != 0) {
/* Access right violation */
qemu_log_mask(CPU_LOG_MMU, "PTE access rejected\n");
if (rwx == 2) {
int srr1 = 0;
if (PAGE_EXEC & ~pp_prot) {
if (PAGE_EXEC & ~exec_prot) {
srr1 |= SRR1_NOEXEC_GUARD; /* Access violates noexec or guard */
} else if (PAGE_EXEC & ~pp_prot) {
srr1 |= SRR1_PROTFAULT; /* Access violates access authority */
}
if (PAGE_EXEC & ~amr_prot) {