[v3] linux-user: Improve host and guest page size handling

[PATCH v3 06/33] linux-user/nios2: Remove qemu_host_page_size from init_guest_commpage

Posted by Richard Henderson 10 months, 4 weeks ago

Use qemu_real_host_page_size.
If !reserved_va, use MAP_FIXED_NOREPLACE.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 linux-user/elfload.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 96d8d4f84c..4fcc490ce6 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -1531,10 +1531,14 @@ static bool init_guest_commpage(void)
                  0x3a, 0x68, 0x3b, 0x00,  /* trap 0 */
     };
 
-    void *want = g2h_untagged(LO_COMMPAGE & -qemu_host_page_size);
-    void *addr = mmap(want, qemu_host_page_size, PROT_READ | PROT_WRITE,
-                      MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0);
+    int host_page_size = qemu_real_host_page_size();
+    void *want, *addr;
 
+    want = g2h_untagged(LO_COMMPAGE & -host_page_size);
+    addr = mmap(want, host_page_size, PROT_READ | PROT_WRITE,
+                MAP_ANONYMOUS | MAP_PRIVATE |
+                (reserved_va ? MAP_FIXED : MAP_FIXED_NOREPLACE),
+                -1, 0);
     if (addr == MAP_FAILED) {
         perror("Allocating guest commpage");
         exit(EXIT_FAILURE);
@@ -1543,9 +1547,9 @@ static bool init_guest_commpage(void)
         return false;
     }
 
-    memcpy(addr, kuser_page, sizeof(kuser_page));
+    memcpy(g2h_untagged(LO_COMMPAGE), kuser_page, sizeof(kuser_page));
 
-    if (mprotect(addr, qemu_host_page_size, PROT_READ)) {
+    if (mprotect(addr, host_page_size, PROT_READ)) {
         perror("Protecting guest commpage");
         exit(EXIT_FAILURE);
     }
-- 
2.34.1

Re: [PATCH v3 06/33] linux-user/nios2: Remove qemu_host_page_size from init_guest_commpage

Posted by Pierrick Bouvier 10 months, 3 weeks ago

On 1/2/24 05:57, Richard Henderson wrote:
> Use qemu_real_host_page_size.
> If !reserved_va, use MAP_FIXED_NOREPLACE.
> 
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   linux-user/elfload.c | 14 +++++++++-----
>   1 file changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/linux-user/elfload.c b/linux-user/elfload.c
> index 96d8d4f84c..4fcc490ce6 100644
> --- a/linux-user/elfload.c
> +++ b/linux-user/elfload.c
> @@ -1531,10 +1531,14 @@ static bool init_guest_commpage(void)
>                    0x3a, 0x68, 0x3b, 0x00,  /* trap 0 */
>       };
>   
> -    void *want = g2h_untagged(LO_COMMPAGE & -qemu_host_page_size);
> -    void *addr = mmap(want, qemu_host_page_size, PROT_READ | PROT_WRITE,
> -                      MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0);
> +    int host_page_size = qemu_real_host_page_size();
> +    void *want, *addr;
>   
> +    want = g2h_untagged(LO_COMMPAGE & -host_page_size);
> +    addr = mmap(want, host_page_size, PROT_READ | PROT_WRITE,
> +                MAP_ANONYMOUS | MAP_PRIVATE |
> +                (reserved_va ? MAP_FIXED : MAP_FIXED_NOREPLACE),
> +                -1, 0);
>       if (addr == MAP_FAILED) {
>           perror("Allocating guest commpage");
>           exit(EXIT_FAILURE);
> @@ -1543,9 +1547,9 @@ static bool init_guest_commpage(void)
>           return false;
>       }
>   
> -    memcpy(addr, kuser_page, sizeof(kuser_page));
> +    memcpy(g2h_untagged(LO_COMMPAGE), kuser_page, sizeof(kuser_page));
>   
> -    if (mprotect(addr, qemu_host_page_size, PROT_READ)) {
> +    if (mprotect(addr, host_page_size, PROT_READ)) {
>           perror("Protecting guest commpage");
>           exit(EXIT_FAILURE);
>       }

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>