| Message ID | 20240828091956.127760-2-frediano.ziglio@cloud.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2,1/2] x86/boot: Avoid relocations in trampoline code to physical addresses | expand |
On 28.08.2024 11:19, Frediano Ziglio wrote: > Add virt_addr macro to make more clear the address we want and making > symbol search easier. This is not good enough a reason to make this change, especially in light of the address space randomization aspect mentioned in reply to patch 1. While there it only _may_ get in the way, here I'm sure it _will_. Which isn't to say we can't go this route, just that it needs proper weighing (and hence a better justification to start from). Jan
diff --git a/xen/arch/x86/boot/trampoline.S b/xen/arch/x86/boot/trampoline.S index 3a6eb942a7..02c713af91 100644 --- a/xen/arch/x86/boot/trampoline.S +++ b/xen/arch/x86/boot/trampoline.S @@ -40,6 +40,7 @@ .popsection #define phys_addr(sym) sym ## _PA +#define virt_addr(sym) (sym ## _PA + __XEN_VIRT_START) /* Start of the permanent trampoline code. */ @@ -120,7 +121,7 @@ trampoline_protmode_entry: .code64 start64: /* Jump to high mappings. */ - movabs $__high_start, %rdi + movabs $virt_addr(__high_start), %rdi jmpq *%rdi #include "video.h" diff --git a/xen/arch/x86/boot/wakeup.S b/xen/arch/x86/boot/wakeup.S index ae4dd5eb40..5ac8ba1fb6 100644 --- a/xen/arch/x86/boot/wakeup.S +++ b/xen/arch/x86/boot/wakeup.S @@ -156,7 +156,7 @@ wakeup_32: .code64 wakeup_64: /* Jump to high mappings and the higher-level wakeup code. */ - movabs $s3_resume, %rbx + movabs $virt_addr(s3_resume), %rbx jmp *%rbx bogus_saved_magic: diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S index 5cfbd2524a..b200606278 100644 --- a/xen/arch/x86/xen.lds.S +++ b/xen/arch/x86/xen.lds.S @@ -77,6 +77,8 @@ SECTIONS DEFINE_PA_ADDRESS(start); DEFINE_PA_ADDRESS(saved_magic); DEFINE_PA_ADDRESS(idle_pg_table); + DEFINE_PA_ADDRESS(__high_start); + DEFINE_PA_ADDRESS(s3_resume); . = __XEN_VIRT_START + XEN_IMG_OFFSET; _start = .;
Add virt_addr macro to make more clear the address we want and making symbol search easier. We don't generate direct absolute symbols to virtual addresses to avoid linker warnings. Signed-off-by: Frediano Ziglio <frediano.ziglio@cloud.com> --- xen/arch/x86/boot/trampoline.S | 3 ++- xen/arch/x86/boot/wakeup.S | 2 +- xen/arch/x86/xen.lds.S | 2 ++ 3 files changed, 5 insertions(+), 2 deletions(-)