svn commit: r349906 - head/sys/powerpc/powerpc

[Justin Hibbits]

Author: jhibbits
Date: Thu Jul 11 03:29:25 2019
New Revision: 349906
URL: https://svnweb.freebsd.org/changeset/base/349906

Log:
  powerpc: Only worry about the lower 32 bits of SP in a 32-bit process
  
  Summary:
  Running a 32-bit process on a 64-bit POWER CPU may still use all 64-bits
  in calculations, while ignoring the upper 32 bits for addressing
  storage.  It so happens that some processes end up with r1 (SP) having
  bit 31 set in some cases (33-bit address).  Writing out to this 33-bit
  address obviosly fails.  Since the CPU ignores the upper bits, we should
  as well.
  
  sendsig() and cpu_fetch_syscall_args() appear to be the only functions
  that actually rely on userspace register values for copy in/out, and
  cpu_fetch_syscall_args() doesn't seem to be bitten in practice yet.
  
  Reviewed By: luporl
  Differential Revision: https://reviews.freebsd.org/D20896

Modified:
  head/sys/powerpc/powerpc/exec_machdep.c

Modified: head/sys/powerpc/powerpc/exec_machdep.c
==============================================================================
--- head/sys/powerpc/powerpc/exec_machdep.c	Thu Jul 11 02:43:23 2019	(r349905)
+++ head/sys/powerpc/powerpc/exec_machdep.c	Thu Jul 11 03:29:25 2019	(r349906)
@@ -144,6 +144,7 @@ sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask
 	#endif
 	size_t sfpsize;
 	caddr_t sfp, usfp;
+	register_t sp;
 	int oonstack, rndfsize;
 	int sig;
 	int code;
@@ -155,7 +156,6 @@ sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask
 	psp = p->p_sigacts;
 	mtx_assert(&psp->ps_mtx, MA_OWNED);
 	tf = td->td_frame;
-	oonstack = sigonstack(tf->fixreg[1]);
 
 	/*
 	 * Fill siginfo structure.
@@ -173,6 +173,8 @@ sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask
 		sfp = (caddr_t)&sf32;
 		sfpsize = sizeof(sf32);
 		rndfsize = roundup(sizeof(sf32), 16);
+		sp = (uint32_t)tf->fixreg[1];
+		oonstack = sigonstack(sp);
 
 		/*
 		 * Save user context
@@ -203,6 +205,8 @@ sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask
 		#else
 		rndfsize = roundup(sizeof(sf), 16);
 		#endif
+		sp = tf->fixreg[1];
+		oonstack = sigonstack(sp);
 
 		/*
 		 * Save user context
@@ -232,7 +236,7 @@ sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask
 		usfp = (void *)(((uintptr_t)td->td_sigstk.ss_sp +
 		   td->td_sigstk.ss_size - rndfsize) & ~0xFul);
 	} else {
-		usfp = (void *)((tf->fixreg[1] - rndfsize) & ~0xFul);
+		usfp = (void *)((sp - rndfsize) & ~0xFul);
 	}
 
 	/*