diff mbox series

[v7,02/38] x86/boot: convert consider_modules to struct boot_module

Message ID 20241021004613.18793-3-dpsmith@apertussolutions.com (mailing list archive)
State New
Headers show
Series Boot modules for Hyperlaunch | expand

Commit Message

Daniel P. Smith Oct. 21, 2024, 12:45 a.m. UTC 
To start transitioning consider_modules() over to struct boot_module, begin
with taking the array of struct boot_modules but use the temporary struct
element mod.

No functional change intended.

Signed-off-by: Daniel P. Smith <dpsmith@apertussolutions.com>
Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>
---
Changes since v5:
- drop unnecessary type cast
---
 xen/arch/x86/setup.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

Comments

Andrew Cooper Oct. 21, 2024, 9:53 a.m. UTC | #1 
On 21/10/2024 1:45 am, Daniel P. Smith wrote:
> To start transitioning consider_modules() over to struct boot_module, begin
> with taking the array of struct boot_modules but use the temporary struct
> element mod.
>
> No functional change intended.
>
> Signed-off-by: Daniel P. Smith <dpsmith@apertussolutions.com>
> Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>

I've taken patch 1 (currently in testing to push).

However, this change breaks PV Shim (same test case that I debugged the
OSSTest failure with on Saturday).

(XEN) PVH start info: (pa 0000ffc0)
(XEN)   version:    1
(XEN)   flags:      0
(XEN)   nr_modules: 2
(XEN)   modlist_pa: 000000000000ff60
(XEN)   cmdline_pa: 000000000000ffa0
(XEN)   cmdline:    'pv-shim console=xen,pv'
(XEN)   rsdp_pa:    00000000fc008000
(XEN)     mod[0].pa:         0000000001042000
(XEN)     mod[0].size:       0000000006907440
(XEN)     mod[0].cmdline_pa: 0000000000000000
(XEN)     mod[1].pa:         00000000016d9000
(XEN)     mod[1].size:       0000000019870751
(XEN)     mod[1].cmdline_pa: 0000000000000000
(XEN) Bootloader: PVH Directboot
(XEN) Command line: pv-shim console=xen,pv
(XEN) Xen image load base address: 0
...
(XEN) ----[ Xen-4.20-unstable  x86_64  debug=y ubsan=y  Not tainted ]----
(XEN) CPU:    0
(XEN) RIP:    e008:[<ffff82d040a51d38>]
arch/x86/pv/dom0_build.c#dom0_construct+0x2020/0x24eb
...
(XEN) Xen call trace:
(XEN)    [<ffff82d040a51d38>] R
arch/x86/pv/dom0_build.c#dom0_construct+0x2020/0x24eb
(XEN)    [<ffff82d040a52222>] F dom0_construct_pv+0x1f/0xcd
(XEN)    [<ffff82d040a7bb27>] F construct_dom0+0xad/0xc0
(XEN)    [<ffff82d040a6eb3f>] F __start_xen+0x50f2/0x53aa
(XEN)    [<ffff82d040206184>] F __high_start+0x94/0xa0
...
(XEN) Pagetable walk from ffff8287fffffff8:
(XEN)  L4[0x105] = 000000001fa17063 ffffffffffffffff
(XEN)  L3[0x01f] = 0000000000000000 ffffffffffffffff
(XEN)
(XEN) ****************************************
(XEN) Panic on CPU 0:
(XEN) FATAL PAGE FAULT
(XEN) [error_code=0000]
(XEN) Faulting linear address: ffff8287fffffff8
(XEN) ****************************************

We've got a wild access, but it's not clear exactly what's going on here.

addr2line says it's line 904 which is in the middle of the
page_list_for_each() loop setting up the physmap.

My gut feeling is that the pointer -> array conversion in
consider_modules() isn't correct, because that's literally the only
non-trivial change, but I can't spot anything concretely wrong...

~Andrew
Andrew Cooper Oct. 22, 2024, 1:29 p.m. UTC | #2 
On 21/10/2024 10:53 am, Andrew Cooper wrote:
> On 21/10/2024 1:45 am, Daniel P. Smith wrote:
>> To start transitioning consider_modules() over to struct boot_module, begin
>> with taking the array of struct boot_modules but use the temporary struct
>> element mod.
>>
>> No functional change intended.
>>
>> Signed-off-by: Daniel P. Smith <dpsmith@apertussolutions.com>
>> Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>
> I've taken patch 1 (currently in testing to push).
>
> However, this change breaks PV Shim (same test case that I debugged the
> OSSTest failure with on Saturday).
>
> (XEN) PVH start info: (pa 0000ffc0)
> (XEN)   version:    1
> (XEN)   flags:      0
> (XEN)   nr_modules: 2
> (XEN)   modlist_pa: 000000000000ff60
> (XEN)   cmdline_pa: 000000000000ffa0
> (XEN)   cmdline:    'pv-shim console=xen,pv'
> (XEN)   rsdp_pa:    00000000fc008000
> (XEN)     mod[0].pa:         0000000001042000
> (XEN)     mod[0].size:       0000000006907440
> (XEN)     mod[0].cmdline_pa: 0000000000000000
> (XEN)     mod[1].pa:         00000000016d9000
> (XEN)     mod[1].size:       0000000019870751
> (XEN)     mod[1].cmdline_pa: 0000000000000000
> (XEN) Bootloader: PVH Directboot
> (XEN) Command line: pv-shim console=xen,pv
> (XEN) Xen image load base address: 0
> ...
> (XEN) ----[ Xen-4.20-unstable  x86_64  debug=y ubsan=y  Not tainted ]----
> (XEN) CPU:    0
> (XEN) RIP:    e008:[<ffff82d040a51d38>]
> arch/x86/pv/dom0_build.c#dom0_construct+0x2020/0x24eb
> ...
> (XEN) Xen call trace:
> (XEN)    [<ffff82d040a51d38>] R
> arch/x86/pv/dom0_build.c#dom0_construct+0x2020/0x24eb
> (XEN)    [<ffff82d040a52222>] F dom0_construct_pv+0x1f/0xcd
> (XEN)    [<ffff82d040a7bb27>] F construct_dom0+0xad/0xc0
> (XEN)    [<ffff82d040a6eb3f>] F __start_xen+0x50f2/0x53aa
> (XEN)    [<ffff82d040206184>] F __high_start+0x94/0xa0
> ...
> (XEN) Pagetable walk from ffff8287fffffff8:
> (XEN)  L4[0x105] = 000000001fa17063 ffffffffffffffff
> (XEN)  L3[0x01f] = 0000000000000000 ffffffffffffffff
> (XEN)
> (XEN) ****************************************
> (XEN) Panic on CPU 0:
> (XEN) FATAL PAGE FAULT
> (XEN) [error_code=0000]
> (XEN) Faulting linear address: ffff8287fffffff8
> (XEN) ****************************************
>
> We've got a wild access, but it's not clear exactly what's going on here.
>
> addr2line says it's line 904 which is in the middle of the
> page_list_for_each() loop setting up the physmap.
>
> My gut feeling is that the pointer -> array conversion in
> consider_modules() isn't correct, because that's literally the only
> non-trivial change, but I can't spot anything concretely wrong...

To follow up, this isn't really the fault of this patch.

It's a hindenbug left by prior patches.  Fix at
https://lore.kernel.org/xen-devel/20241022124114.84498-1-andrew.cooper3@citrix.com/T/#u

~Andrew
diff mbox series

Patch

diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index db670258d650..1eafa0a61e0e 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -645,7 +645,7 @@  static void __init noinline move_xen(void)
 #undef BOOTSTRAP_MAP_LIMIT
 
 static uint64_t __init consider_modules(
-    uint64_t s, uint64_t e, uint32_t size, const module_t *mod,
+    uint64_t s, uint64_t e, uint32_t size, const struct boot_module mods[],
     unsigned int nr_mods, unsigned int this_mod)
 {
     unsigned int i;
@@ -655,20 +655,20 @@  static uint64_t __init consider_modules(
 
     for ( i = 0; i < nr_mods ; ++i )
     {
-        uint64_t start = (uint64_t)mod[i].mod_start << PAGE_SHIFT;
-        uint64_t end = start + PAGE_ALIGN(mod[i].mod_end);
+        uint64_t start = pfn_to_paddr(mods[i].mod->mod_start);
+        uint64_t end = start + PAGE_ALIGN(mods[i].mod->mod_end);
 
         if ( i == this_mod )
             continue;
 
         if ( s < end && start < e )
         {
-            end = consider_modules(end, e, size, mod + i + 1,
+            end = consider_modules(end, e, size, &mods[i + 1],
                                    nr_mods - i - 1, this_mod - i - 1);
             if ( end )
                 return end;
 
-            return consider_modules(s, start, size, mod + i + 1,
+            return consider_modules(s, start, size, &mods[i + 1],
                                     nr_mods - i - 1, this_mod - i - 1);
         }
     }
@@ -1451,7 +1451,7 @@  void asmlinkage __init noreturn __start_xen(unsigned long mbi_p)
         {
             /* Don't overlap with modules. */
             end = consider_modules(s, e, reloc_size + mask,
-                                   mod, bi->nr_modules, -1);
+                                   bi->mods, bi->nr_modules, -1);
             end &= ~mask;
         }
         else
@@ -1486,7 +1486,7 @@  void asmlinkage __init noreturn __start_xen(unsigned long mbi_p)
                 continue;
 
             /* Don't overlap with other modules (or Xen itself). */
-            end = consider_modules(s, e, size, mod,
+            end = consider_modules(s, e, size, bi->mods,
                                    bi->nr_modules + relocated, j);
 
             if ( highmem_start && end > highmem_start )
@@ -1513,7 +1513,7 @@  void asmlinkage __init noreturn __start_xen(unsigned long mbi_p)
         while ( !kexec_crash_area.start )
         {
             /* Don't overlap with modules (or Xen itself). */
-            e = consider_modules(s, e, PAGE_ALIGN(kexec_crash_area.size), mod,
+            e = consider_modules(s, e, PAGE_ALIGN(kexec_crash_area.size), bi->mods,
                                  bi->nr_modules + relocated, -1);
             if ( s >= e )
                 break;