Date: Wed, 21 Feb 2018 19:41:10 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-ppc@FreeBSD.org Subject: [Bug 225321] dtrace/powerpc64: System crash Message-ID: <bug-225321-21-9bOtcs2sBN@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-225321-21@https.bugs.freebsd.org/bugzilla/> References: <bug-225321-21@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D225321 --- Comment #5 from Breno Leitao <breno.leitao@gmail.com> --- Looking further, it and the stack is properly set, i.e, the tmpstk is set at the correct place, and the patch above, although not crashing, is far to be correct. This is my new discovery: 1) The tmpstk is being used by powerpc_init(). 2) Powerpc_init calls kdb_enter(), which calls breakpoint(). 3) Breakpoint goes to "dbtrap" label, which reset the stack to tmpstk, overwriting it since the beginning. 4) when dbtrap/breakpoint exits, the stack is a mess, causing this problem. To prove that, I created a stack just for the trap, and this seems to fix t= he problem. diff --git a/sys/powerpc/aim/locore64.S b/sys/powerpc/aim/locore64.S index f283ba6489b..3dd1ca4092d 100644 --- a/sys/powerpc/aim/locore64.S +++ b/sys/powerpc/aim/locore64.S @@ -58,9 +58,13 @@ GLOBAL(__endkernel) #define TMPSTKSZ 16384 /* 16K temporary stack */ GLOBAL(tmpstk) .space TMPSTKSZ - TOC_ENTRY(tmpstk) +#define TRAPSTKSZ 4096 +GLOBAL(trapstk) + .space TRAPSTKSZ +TOC_ENTRY(trapstk) + /* * Entry point for bootloaders that do not fully implement ELF and start * at the beginning of the image (kexec, notably). In its own section so diff --git a/sys/powerpc/aim/trap_subr64.S b/sys/powerpc/aim/trap_subr64.S index 7ef41d90ffe..ffae46fa3f6 100644 --- a/sys/powerpc/aim/trap_subr64.S +++ b/sys/powerpc/aim/trap_subr64.S @@ -805,9 +805,9 @@ dbtrap: andi. %r1,%r1,0xff00 mtsprg3 %r1 - ld %r1,TRAP_TOCBASE(0) /* get new SP */ - ld %r1,TOC_REF(tmpstk)(%r1) - addi %r1,%r1,(TMPSTKSZ-48) + GET_TOCBASE(%r1) + ld %r1,TOC_REF(trapstk)(%r1) + addi %r1,%r1,(TRAPSTKSZ-48) FRAME_SETUP(PC_DBSAVE) /* Call C trap code: */ --=20 You are receiving this mail because: You are the assignee for the bug.=
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