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authorPeter Maydell <peter.maydell@linaro.org>2018-08-14 17:17:19 +0100
committerPeter Maydell <peter.maydell@linaro.org>2018-08-14 17:17:19 +0100
commit20cb6ae4724d05cbbda0d9ceec7e357d646b6886 (patch)
tree729732c599f12ada3c5ad9182bb49892e959fcc7 /accel
parent9739e3767af19096898d63eb9f2f0ff5004797d2 (diff)
accel/tcg: Return -1 for execution from MMIO regions in get_page_addr_code()
Now that all the callers can handle get_page_addr_code() returning -1, remove all the code which tries to handle execution from MMIO regions or small-MMU-region RAM areas. This will mean that we can correctly execute from these areas, rather than ending up either aborting QEMU or delivering an incorrect guest exception. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Tested-by: Cédric Le Goater <clg@kaod.org> Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Message-id: 20180710160013.26559-6-peter.maydell@linaro.org
Diffstat (limited to 'accel')
-rw-r--r--accel/tcg/cputlb.c95
1 files changed, 10 insertions, 85 deletions
diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
index 51b1193044..754795ff25 100644
--- a/accel/tcg/cputlb.c
+++ b/accel/tcg/cputlb.c
@@ -741,39 +741,6 @@ void tlb_set_page(CPUState *cpu, target_ulong vaddr,
prot, mmu_idx, size);
}
-static void report_bad_exec(CPUState *cpu, target_ulong addr)
-{
- /* Accidentally executing outside RAM or ROM is quite common for
- * several user-error situations, so report it in a way that
- * makes it clear that this isn't a QEMU bug and provide suggestions
- * about what a user could do to fix things.
- */
- error_report("Trying to execute code outside RAM or ROM at 0x"
- TARGET_FMT_lx, addr);
- error_printf("This usually means one of the following happened:\n\n"
- "(1) You told QEMU to execute a kernel for the wrong machine "
- "type, and it crashed on startup (eg trying to run a "
- "raspberry pi kernel on a versatilepb QEMU machine)\n"
- "(2) You didn't give QEMU a kernel or BIOS filename at all, "
- "and QEMU executed a ROM full of no-op instructions until "
- "it fell off the end\n"
- "(3) Your guest kernel has a bug and crashed by jumping "
- "off into nowhere\n\n"
- "This is almost always one of the first two, so check your "
- "command line and that you are using the right type of kernel "
- "for this machine.\n"
- "If you think option (3) is likely then you can try debugging "
- "your guest with the -d debug options; in particular "
- "-d guest_errors will cause the log to include a dump of the "
- "guest register state at this point.\n\n"
- "Execution cannot continue; stopping here.\n\n");
-
- /* Report also to the logs, with more detail including register dump */
- qemu_log_mask(LOG_GUEST_ERROR, "qemu: fatal: Trying to execute code "
- "outside RAM or ROM at 0x" TARGET_FMT_lx "\n", addr);
- log_cpu_state_mask(LOG_GUEST_ERROR, cpu, CPU_DUMP_FPU | CPU_DUMP_CCOP);
-}
-
static inline ram_addr_t qemu_ram_addr_from_host_nofail(void *ptr)
{
ram_addr_t ram_addr;
@@ -963,7 +930,6 @@ tb_page_addr_t get_page_addr_code(CPUArchState *env, target_ulong addr)
MemoryRegionSection *section;
CPUState *cpu = ENV_GET_CPU(env);
CPUIOTLBEntry *iotlbentry;
- hwaddr physaddr, mr_offset;
index = (addr >> TARGET_PAGE_BITS) & (CPU_TLB_SIZE - 1);
mmu_idx = cpu_mmu_index(env, true);
@@ -977,65 +943,24 @@ tb_page_addr_t get_page_addr_code(CPUArchState *env, target_ulong addr)
if (unlikely(env->tlb_table[mmu_idx][index].addr_code & TLB_RECHECK)) {
/*
* This is a TLB_RECHECK access, where the MMU protection
- * covers a smaller range than a target page, and we must
- * repeat the MMU check here. This tlb_fill() call might
- * longjump out if this access should cause a guest exception.
- */
- int index;
- target_ulong tlb_addr;
-
- tlb_fill(cpu, addr, 0, MMU_INST_FETCH, mmu_idx, 0);
-
- index = (addr >> TARGET_PAGE_BITS) & (CPU_TLB_SIZE - 1);
- tlb_addr = env->tlb_table[mmu_idx][index].addr_code;
- if (!(tlb_addr & ~(TARGET_PAGE_MASK | TLB_RECHECK))) {
- /* RAM access. We can't handle this, so for now just stop */
- cpu_abort(cpu, "Unable to handle guest executing from RAM within "
- "a small MPU region at 0x" TARGET_FMT_lx, addr);
- }
- /*
- * Fall through to handle IO accesses (which will almost certainly
- * also result in failure)
+ * covers a smaller range than a target page. Return -1 to
+ * indicate that we cannot simply execute from RAM here;
+ * we will perform the necessary repeat of the MMU check
+ * when the "execute a single insn" code performs the
+ * load of the guest insn.
*/
+ return -1;
}
iotlbentry = &env->iotlb[mmu_idx][index];
section = iotlb_to_section(cpu, iotlbentry->addr, iotlbentry->attrs);
mr = section->mr;
if (memory_region_is_unassigned(mr)) {
- qemu_mutex_lock_iothread();
- if (memory_region_request_mmio_ptr(mr, addr)) {
- qemu_mutex_unlock_iothread();
- /* A MemoryRegion is potentially added so re-run the
- * get_page_addr_code.
- */
- return get_page_addr_code(env, addr);
- }
- qemu_mutex_unlock_iothread();
-
- /* Give the new-style cpu_transaction_failed() hook first chance
- * to handle this.
- * This is not the ideal place to detect and generate CPU
- * exceptions for instruction fetch failure (for instance
- * we don't know the length of the access that the CPU would
- * use, and it would be better to go ahead and try the access
- * and use the MemTXResult it produced). However it is the
- * simplest place we have currently available for the check.
- */
- mr_offset = (iotlbentry->addr & TARGET_PAGE_MASK) + addr;
- physaddr = mr_offset +
- section->offset_within_address_space -
- section->offset_within_region;
- cpu_transaction_failed(cpu, physaddr, addr, 0, MMU_INST_FETCH, mmu_idx,
- iotlbentry->attrs, MEMTX_DECODE_ERROR, 0);
-
- cpu_unassigned_access(cpu, addr, false, true, 0, 4);
- /* The CPU's unassigned access hook might have longjumped out
- * with an exception. If it didn't (or there was no hook) then
- * we can't proceed further.
+ /*
+ * Not guest RAM, so there is no ram_addr_t for it. Return -1,
+ * and we will execute a single insn from this device.
*/
- report_bad_exec(cpu, addr);
- exit(1);
+ return -1;
}
p = (void *)((uintptr_t)addr + env->tlb_table[mmu_idx][index].addend);
return qemu_ram_addr_from_host_nofail(p);