git: b029ef7fe618 - main - Restrict spsr updated in the arm64 set_regs*

[Andrew Turner]

The branch main has been updated by andrew:

URL: 
https://cgit.FreeBSD.org/src/commit/?id=b029ef7fe618c6fa0482958422cc362905c15376

commit b029ef7fe618c6fa0482958422cc362905c15376
Author:     Andrew Turner <and...@freebsd.org>
AuthorDate: 2021-09-13 15:24:34 +0000
Commit:     Andrew Turner <and...@freebsd.org>
CommitDate: 2021-09-13 15:32:50 +0000

    Restrict spsr updated in the arm64 set_regs*
    
    When using ptrace(2) on arm64 to set registers in a 32-bit program we
    need to take care to only set some of the fields. Follow the existing
    arm64 path and only let the user set the flags fields. This is also the
    case in the arm kernel so fixes a change in behaviour between the two.
    
    While here update set_regs to only set spsr and elr once.
    
    Sponsored by:   The FreeBSD Foundation
---
 sys/arm64/arm64/machdep.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/sys/arm64/arm64/machdep.c b/sys/arm64/arm64/machdep.c
index ee6f5157f5f3..89c4f21134f8 100644
--- a/sys/arm64/arm64/machdep.c
+++ b/sys/arm64/arm64/machdep.c
@@ -254,9 +254,7 @@ set_regs(struct thread *td, struct reg *regs)
        frame = td->td_frame;
        frame->tf_sp = regs->sp;
        frame->tf_lr = regs->lr;
-       frame->tf_elr = regs->elr;
        frame->tf_spsr &= ~PSR_FLAGS;
-       frame->tf_spsr |= regs->spsr & PSR_FLAGS;
 
        memcpy(frame->tf_x, regs->x, sizeof(frame->tf_x));
 
@@ -268,9 +266,13 @@ set_regs(struct thread *td, struct reg *regs)
                 * it put it.
                 */
                frame->tf_elr = regs->x[15];
-               frame->tf_spsr = regs->x[16] & PSR_FLAGS;
-       }
+               frame->tf_spsr |= regs->x[16] & PSR_FLAGS;
+       } else
 #endif
+       {
+               frame->tf_elr = regs->elr;
+               frame->tf_spsr |= regs->spsr & PSR_FLAGS;
+       }
        return (0);
 }
 
@@ -490,7 +492,8 @@ set_regs32(struct thread *td, struct reg32 *regs)
        tf->tf_x[13] = regs->r_sp;
        tf->tf_x[14] = regs->r_lr;
        tf->tf_elr = regs->r_pc;
-       tf->tf_spsr = regs->r_cpsr;
+       tf->tf_spsr &= ~PSR_FLAGS;
+       tf->tf_spsr |= regs->r_cpsr & PSR_FLAGS;
 
        return (0);
 }
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