Linux guests, when using more than 4GB of RAM, may end up using 1GB pages
to store (kernel) data. When this happens, we're unable to debug a running
Linux kernel with GDB:
(gdb) p node_data[0]->node_id
Cannot access memory at address 0xffff88013fffd3a0
(gdb)
GDB returns this error because x86_cpu_get_phys_page_debug() doesn't support
translating 1GB pages in IA-32e paging mode and returns an error to GDB.
This commit adds support for 1GB page translation for IA32e paging.
Signed-off-by: Luiz capitulino <address@hidden>
---
- I'm proposing this patch for 2.0 because GDB debugging of large Linux
guests is kind of broken
- Changelog v2:
- Move PS bit handling to if (env->hflags & HF_LMA_MASK) block
- Update changelog
target-i386/helper.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/target-i386/helper.c b/target-i386/helper.c
index 4f447b8..7cee501 100644
--- a/target-i386/helper.c
+++ b/target-i386/helper.c
@@ -941,6 +941,14 @@ hwaddr x86_cpu_get_phys_page_debug(CPUState *cs, vaddr
addr)
pdpe = ldq_phys(cs->as, pdpe_addr);
if (!(pdpe & PG_PRESENT_MASK))
return -1;
+
+ if (pdpe & PG_PSE_MASK) {
+ page_size = 1024 * 1024 * 1024;
+ pte = pdpe & ~( (page_size - 1) & ~0xfff);
+ pte &= ~(PG_NX_MASK | PG_HI_USER_MASK);
+ goto out;
+ }
+
} else
#endif
{
@@ -993,6 +1001,7 @@ hwaddr x86_cpu_get_phys_page_debug(CPUState *cs, vaddr
addr)
pte = pte & env->a20_mask;
}
+out:
page_offset = (addr & TARGET_PAGE_MASK) & (page_size - 1);
paddr = (pte & TARGET_PAGE_MASK) + page_offset;
return paddr;