diff mbox series

target/avr: Support probe argument to tlb_fill

Message ID 20220823050718.1930676-1-richard.henderson@linaro.org
State Superseded
Headers show
Series target/avr: Support probe argument to tlb_fill | expand

Commit Message

Richard Henderson Aug. 23, 2022, 5:07 a.m. UTC 
While there are no target-specific nonfaulting probes,
generic code may grow some uses at some point.

Note that the attrs argument was incorrect -- it should have
been MEMTXATTRS_UNSPECIFIED. Just use the simpler interface.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/avr/helper.c | 46 ++++++++++++++++++++++++++++-----------------
 1 file changed, 29 insertions(+), 17 deletions(-)

Comments

Philippe Mathieu-Daudé Aug. 25, 2022, 2:09 p.m. UTC | #1 
On 23/8/22 07:07, Richard Henderson wrote:
> While there are no target-specific nonfaulting probes,
> generic code may grow some uses at some point.
> 
> Note that the attrs argument was incorrect -- it should have
> been MEMTXATTRS_UNSPECIFIED. Just use the simpler interface.
> 
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   target/avr/helper.c | 46 ++++++++++++++++++++++++++++-----------------
>   1 file changed, 29 insertions(+), 17 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
diff mbox series

Patch

diff --git a/target/avr/helper.c b/target/avr/helper.c
index db76452f9a..82284f8997 100644
--- a/target/avr/helper.c
+++ b/target/avr/helper.c
@@ -102,38 +102,50 @@  bool avr_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
                       MMUAccessType access_type, int mmu_idx,
                       bool probe, uintptr_t retaddr)
 {
-    int prot = 0;
-    MemTxAttrs attrs = {};
+    int prot, page_size = TARGET_PAGE_SIZE;
     uint32_t paddr;
 
     address &= TARGET_PAGE_MASK;
 
     if (mmu_idx == MMU_CODE_IDX) {
-        /* access to code in flash */
+        /* Access to code in flash. */
         paddr = OFFSET_CODE + address;
         prot = PAGE_READ | PAGE_EXEC;
-        if (paddr + TARGET_PAGE_SIZE > OFFSET_DATA) {
+        if (paddr >= OFFSET_DATA) {
+            /*
+             * This should not be possible via any architectural operations.
+             * There is certainly not an exception that we can deliver.
+             * Accept probing that might come from generic code.
+             */
+            if (probe) {
+                return false;
+            }
             error_report("execution left flash memory");
             abort();
         }
-    } else if (address < NUMBER_OF_CPU_REGISTERS + NUMBER_OF_IO_REGISTERS) {
-        /*
-         * access to CPU registers, exit and rebuilt this TB to use full access
-         * incase it touches specially handled registers like SREG or SP
-         */
-        AVRCPU *cpu = AVR_CPU(cs);
-        CPUAVRState *env = &cpu->env;
-        env->fullacc = 1;
-        cpu_loop_exit_restore(cs, retaddr);
     } else {
-        /* access to memory. nothing special */
+        /* Access to memory. */
         paddr = OFFSET_DATA + address;
         prot = PAGE_READ | PAGE_WRITE;
+        if (address < NUMBER_OF_CPU_REGISTERS + NUMBER_OF_IO_REGISTERS) {
+            /*
+             * Access to CPU registers, exit and rebuilt this TB to use
+             * full access in case it touches specially handled registers
+             * like SREG or SP.  For probing, set page_size = 1, in order
+             * to force tlb_fill to be called for the next access.
+             */
+            if (probe) {
+                page_size = 1;
+            } else {
+                AVRCPU *cpu = AVR_CPU(cs);
+                CPUAVRState *env = &cpu->env;
+                env->fullacc = 1;
+                cpu_loop_exit_restore(cs, retaddr);
+            }
+        }
     }
 
-    tlb_set_page_with_attrs(cs, address, paddr, attrs, prot,
-                            mmu_idx, TARGET_PAGE_SIZE);
-
+    tlb_set_page(cs, address, paddr, prot, mmu_idx, page_size);
     return true;
 }