commit 6c5bf79b69f911560fbf82214c0971af6e58e682 upstream.
Systems using kpti enter and exit the kernel through a trampoline mapping
that is always mapped, even when the kernel is not. tramp_valias is a macro
to find the address of a symbol in the trampoline mapping.
Adding extra sets of vectors will expand the size of the entry.tramp.text
section to beyond 4K. tramp_valias will be unable to generate addresses
for symbols beyond 4K as it uses the 12 bit immediate of the add
instruction.
As there are now two registers available when tramp_alias is called,
use the extra register to avoid the 4K limit of the 12 bit immediate.
Reviewed-by: Russell King (Oracle) <[email protected]>
Reviewed-by: Catalin Marinas <[email protected]>
[ Removed SDEI for backport ]
Signed-off-by: James Morse <[email protected]>
---
arch/arm64/kernel/entry.S | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 0669d05bd63c..f455557eaaaa 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -139,9 +139,12 @@
.org .Lventry_start\@ + 128 // Did we overflow the ventry slot?
.endm
- .macro tramp_alias, dst, sym
+ .macro tramp_alias, dst, sym, tmp
mov_q \dst, TRAMP_VALIAS
- add \dst, \dst, #(\sym - .entry.tramp.text)
+ adr_l \tmp, \sym
+ add \dst, \dst, \tmp
+ adr_l \tmp, .entry.tramp.text
+ sub \dst, \dst, \tmp
.endm
// This macro corrupts x0-x3. It is the caller's duty
@@ -366,10 +369,10 @@ alternative_else_nop_endif
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
bne 4f
msr far_el1, x29
- tramp_alias x30, tramp_exit_native
+ tramp_alias x30, tramp_exit_native, x29
br x30
4:
- tramp_alias x30, tramp_exit_compat
+ tramp_alias x30, tramp_exit_compat, x29
br x30
#endif
.else
--
2.30.2