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| author | andrew <andrew@FreeBSD.org> | 2017-04-19 15:59:16 +0000 |
|---|---|---|
| committer | andrew <andrew@FreeBSD.org> | 2017-04-19 15:59:16 +0000 |
| commit | b7aef29707b4ceb8e2e598038a1b6c6bedcd075e (patch) | |
| tree | bd6e3b1077a26cecbca5807f2373f5e6d8f98193 /sys/arm64 | |
| parent | 4b14b18364b6ec3f1121c654a7d3bf41cfff77fe (diff) | |
| download | FreeBSD-src-b7aef29707b4ceb8e2e598038a1b6c6bedcd075e.zip FreeBSD-src-b7aef29707b4ceb8e2e598038a1b6c6bedcd075e.tar.gz | |
MFC 313772:
Load the new sp_el0 with interrupts disabled in fork_trampoline. If an
interrupt arrives in fork_trampoline after sp_el0 was written we may then
switch to a new thread, enter userland so change this stack pointer, then
return to this code with the wrong value. This fixes this case by moving
the load of sp_el0 until after interrupts have been disabled.
Diffstat (limited to 'sys/arm64')
| -rw-r--r-- | sys/arm64/arm64/swtch.S | 13 |
1 files changed, 6 insertions, 7 deletions
diff --git a/sys/arm64/arm64/swtch.S b/sys/arm64/arm64/swtch.S index 1b501a49..299e590 100644 --- a/sys/arm64/arm64/swtch.S +++ b/sys/arm64/arm64/swtch.S @@ -241,11 +241,6 @@ ENTRY(fork_trampoline) mov fp, #0 /* Stack traceback stops here. */ bl _C_LABEL(fork_exit) - /* Restore sp and lr */ - ldp x0, x1, [sp] - msr sp_el0, x0 - mov lr, x1 - /* Restore the registers other than x0 and x1 */ ldp x2, x3, [sp, #TF_X + 2 * 8] ldp x4, x5, [sp, #TF_X + 4 * 8] @@ -261,14 +256,18 @@ ENTRY(fork_trampoline) ldp x24, x25, [sp, #TF_X + 24 * 8] ldp x26, x27, [sp, #TF_X + 26 * 8] ldp x28, x29, [sp, #TF_X + 28 * 8] - /* Skip x30 as it was restored above as lr */ /* * Disable interrupts to avoid - * overwriting spsr_el1 by an IRQ exception. + * overwriting spsr_el1 and sp_el0 by an IRQ exception. */ msr daifset, #2 + /* Restore sp and lr */ + ldp x0, x1, [sp] + msr sp_el0, x0 + mov lr, x1 + /* Restore elr and spsr */ ldp x0, x1, [sp, #16] msr elr_el1, x0 |
