[2/6] accel/tcg: Handle get_page_addr_code() returning -1 in hashtable lookups

Message ID 20180710160013.26559-3-peter.maydell@linaro.org
State New
Headers show
Series
  • accel/tcg: Support execution from MMIO and small MMU regions
Related show

Commit Message

Peter Maydell July 10, 2018, 4 p.m.
When we support execution from non-RAM MMIO regions, get_page_addr_code()
will return -1 to indicate that there is no RAM at the requested address.
Handle this in the cpu-exec TB hashtable lookup code, treating it as
"no match found".

Note that the call to get_page_addr_code() in tb_lookup_cmp() needs
no changes -- a return of -1 will already correctly result in the
function returning false.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 accel/tcg/cpu-exec.c | 3 +++
 1 file changed, 3 insertions(+)

Comments

Richard Henderson July 10, 2018, 6:23 p.m. | #1
On 07/10/2018 09:00 AM, Peter Maydell wrote:
> When we support execution from non-RAM MMIO regions, get_page_addr_code()
> will return -1 to indicate that there is no RAM at the requested address.
> Handle this in the cpu-exec TB hashtable lookup code, treating it as
> "no match found".
> 
> Note that the call to get_page_addr_code() in tb_lookup_cmp() needs
> no changes -- a return of -1 will already correctly result in the
> function returning false.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  accel/tcg/cpu-exec.c | 3 +++
>  1 file changed, 3 insertions(+)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~
Emilio G. Cota July 13, 2018, 4:44 p.m. | #2
On Tue, Jul 10, 2018 at 17:00:09 +0100, Peter Maydell wrote:
> When we support execution from non-RAM MMIO regions, get_page_addr_code()
> will return -1 to indicate that there is no RAM at the requested address.
> Handle this in the cpu-exec TB hashtable lookup code, treating it as
> "no match found".
> 
> Note that the call to get_page_addr_code() in tb_lookup_cmp() needs
> no changes -- a return of -1 will already correctly result in the
> function returning false.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Emilio G. Cota <cota@braap.org>

		E.

Patch

diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
index c738b7f7d6e..6bcb6d99bd7 100644
--- a/accel/tcg/cpu-exec.c
+++ b/accel/tcg/cpu-exec.c
@@ -332,6 +332,9 @@  TranslationBlock *tb_htable_lookup(CPUState *cpu, target_ulong pc,
     desc.trace_vcpu_dstate = *cpu->trace_dstate;
     desc.pc = pc;
     phys_pc = get_page_addr_code(desc.env, pc);
+    if (phys_pc == -1) {
+        return NULL;
+    }
     desc.phys_page1 = phys_pc & TARGET_PAGE_MASK;
     h = tb_hash_func(phys_pc, pc, flags, cf_mask, *cpu->trace_dstate);
     return qht_lookup_custom(&tb_ctx.htable, &desc, h, tb_lookup_cmp);