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xen: Fix warning by adding KERNBASE to modlist_paddr before casting

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Clang 13 produces the following warning for hammer_time_xen():

sys/x86/xen/pv.c:183:19: error: the pointer incremented by -2147483648 refers past the last possible element for an array in 64-bit address space containing 256-bit (32-byte) elements (max possible 576460752303423488 elements) [-Werror,-Warray-bounds]
                    (vm_paddr_t)start_info->modlist_paddr + KERNBASE;
                                ^                               ~~~~~~~~
sys/xen/interface/arch-x86/hvm/start_info.h:131:5: note: array 'modlist_paddr' declared here
    uint64_t modlist_paddr;         /* Physical address of an array of           */
    ^

This is because the expression first casts start_info->modlist_paddr to
struct hvm_modlist_entry * (via vmpaddr_t), and *then* adds KERNBASE,
which is then interpreted as KERNBASE * sizeof(struct
hvm_modlist_entry).

Instead, parenthesize the addition to get the intended result, and cast
it to struct hvm_modlist_entry * afterwards. Also remove the cast to
vmpaddr_t since it is not necessary.

Reviewed by:	royger
MFC after:	3 days
Differential Revision: https://reviews.freebsd.org/D31711
This commit is contained in:
Dimitry Andric 2021-08-29 16:02:31 +02:00
parent 5b8f07b12f
commit 8e3c56d6b6
1 changed files with 1 additions and 1 deletions
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2
sys/x86/xen/pv.c
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@ -180,7 +180,7 @@ hammer_time_xen(vm_paddr_t start_info_paddr)
HYPERVISOR_shutdown(SHUTDOWN_crash);
}
mod = (struct hvm_modlist_entry *)
(vm_paddr_t)start_info->modlist_paddr + KERNBASE;
(start_info->modlist_paddr + KERNBASE);
if (mod[0].paddr >= physfree) {
xc_printf("ERROR: unexpected module memory address\n");
HYPERVISOR_shutdown(SHUTDOWN_crash);