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147 lines
4.5 KiB
147 lines
4.5 KiB
2 years ago
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commit c6f9085ee4e913a0b8260340ac7b75c426b780ce
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Author: John David Anglin <danglin@gcc.gnu.org>
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Date: Fri Feb 18 20:38:25 2022 +0000
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hppa: Fix swapcontext
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This change fixes the failure of stdlib/tst-setcontext2 and
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stdlib/tst-setcontext7 on hppa. The implementation of swapcontext
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in C is broken. C saves the return pointer (rp) and any non
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call-clobbered registers (in this case r3, r4 and r5) on the
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stack. However, the setcontext call in swapcontext pops the
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stack and subsequent calls clobber the saved registers. When
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the context in oucp is restored, both tests fault.
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Here we rewrite swapcontext in assembly code to avoid using
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the stack for register values that need to be used after
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restoration. The getcontext and setcontext routines are
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revised to save and restore register ret1 for normal returns.
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We copy the oucp pointer to ret1. This allows access to
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the old context after calling getcontext and setcontext.
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(cherry picked from commit 71b108d7eb33b2bf3e61d5e92d2a47f74c1f7d96)
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diff --git a/sysdeps/unix/sysv/linux/hppa/getcontext.S b/sysdeps/unix/sysv/linux/hppa/getcontext.S
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index 1405b42819c38993..c8b690aab8ecc47c 100644
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--- a/sysdeps/unix/sysv/linux/hppa/getcontext.S
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+++ b/sysdeps/unix/sysv/linux/hppa/getcontext.S
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@@ -138,6 +138,8 @@ ENTRY(__getcontext)
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stw %r19, -32(%sp)
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.cfi_offset 19, 32
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#endif
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+ stw %ret1, -60(%sp)
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+ .cfi_offset 29, 4
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/* Set up the trampoline registers.
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r20, r23, r24, r25, r26 and r2 are clobbered
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@@ -168,6 +170,7 @@ ENTRY(__getcontext)
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#ifdef PIC
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ldw -32(%sp), %r19
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#endif
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+ ldw -60(%sp), %ret1
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bv %r0(%r2)
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ldwm -64(%sp), %r4
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END(__getcontext)
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diff --git a/sysdeps/unix/sysv/linux/hppa/setcontext.S b/sysdeps/unix/sysv/linux/hppa/setcontext.S
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index 8fc5f5e56cb31f51..e1ae3aefcaac198d 100644
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--- a/sysdeps/unix/sysv/linux/hppa/setcontext.S
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+++ b/sysdeps/unix/sysv/linux/hppa/setcontext.S
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@@ -34,6 +34,8 @@ ENTRY(__setcontext)
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stw %r19, -32(%sp)
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.cfi_offset 19, 32
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#endif
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+ stw %ret1, -60(%sp)
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+ .cfi_offset 29, 4
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/* Save ucp. */
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copy %r26, %r3
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@@ -155,6 +157,7 @@ ENTRY(__setcontext)
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#ifdef PIC
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ldw -32(%r30), %r19
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#endif
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+ ldw -60(%r30), %ret1
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bv %r0(%r2)
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ldwm -64(%r30), %r3
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L(pseudo_end):
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diff --git a/sysdeps/unix/sysv/linux/hppa/swapcontext.c b/sysdeps/unix/sysv/linux/hppa/swapcontext.c
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index f9a8207543c164cb..562f00ff0546177d 100644
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--- a/sysdeps/unix/sysv/linux/hppa/swapcontext.c
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+++ b/sysdeps/unix/sysv/linux/hppa/swapcontext.c
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@@ -18,6 +18,7 @@
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<https://www.gnu.org/licenses/>. */
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#include <ucontext.h>
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+#include "ucontext_i.h"
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extern int __getcontext (ucontext_t *ucp);
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extern int __setcontext (const ucontext_t *ucp);
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@@ -25,17 +26,61 @@ extern int __setcontext (const ucontext_t *ucp);
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int
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__swapcontext (ucontext_t *oucp, const ucontext_t *ucp)
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{
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+ /* Save ucp in stack argument slot. */
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+ asm ("stw %r25,-40(%sp)");
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+ asm (".cfi_offset 25, -40");
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+
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+ /* Save rp for debugger. */
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+ asm ("stw %rp,-20(%sp)");
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+ asm (".cfi_offset 2, -20");
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+
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+ /* Copy rp to ret0 (r28). */
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+ asm ("copy %rp,%ret0");
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+
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+ /* Create a frame. */
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+ asm ("ldo 64(%sp),%sp");
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+ asm (".cfi_def_cfa_offset -64");
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+
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/* Save the current machine context to oucp. */
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- __getcontext (oucp);
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+ asm ("bl __getcontext,%rp");
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+
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+ /* Copy oucp to register ret1 (r29). __getcontext saves and restores it
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+ on a normal return. It is restored from oR29 on reactivation. */
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+ asm ("copy %r26,%ret1");
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+
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+ /* Pop frame. */
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+ asm ("ldo -64(%sp),%sp");
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+ asm (".cfi_def_cfa_offset 0");
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+
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+ /* Load return pointer from oR28. */
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+ asm ("ldw %0(%%ret1),%%rp" : : "i" (oR28));
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+
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+ /* Return if error. */
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+ asm ("or,= %r0,%ret0,%r0");
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+ asm ("bv,n %r0(%rp)");
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+
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+ /* Load sc_sar flag. */
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+ asm ("ldw %0(%%ret1),%%r20" : : "i" (oSAR));
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+
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+ /* Return if oucp context has been reactivated. */
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+ asm ("or,= %r0,%r20,%r0");
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+ asm ("bv,n %r0(%rp)");
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+
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+ /* Mark sc_sar flag. */
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+ asm ("1: ldi 1,%r20");
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+ asm ("stw %%r20,%0(%%ret1)" : : "i" (oSAR));
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+
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+ /* Activate the machine context in ucp. */
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+ asm ("bl __setcontext,%rp");
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+ asm ("ldw -40(%sp),%r26");
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- /* mark sc_sar flag to skip the setcontext call on reactivation. */
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- if (oucp->uc_mcontext.sc_sar == 0) {
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- oucp->uc_mcontext.sc_sar++;
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+ /* Load return pointer. */
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+ asm ("ldw %0(%%ret1),%%rp" : : "i" (oR28));
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- /* Restore the machine context in ucp. */
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- __setcontext (ucp);
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- }
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+ /* A successful call to setcontext does not return. */
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+ asm ("bv,n %r0(%rp)");
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+ /* Make gcc happy. */
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return 0;
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}
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