[gcc r11-9427] Generate illegal instruction fault if LWS syscall returns -EFAULT.

[gcc r11-9427] Generate illegal instruction fault if LWS syscall returns -EFAULT.

[John David Anglin]

https://gcc.gnu.org/g:2c8e273ed11c31fc28784ddd0a8263080f43ba7b

commit r11-9427-g2c8e273ed11c31fc28784ddd0a8263080f43ba7b
Author: John David Anglin <danglin@gcc.gnu.org>
Date:   Sun Jan 2 17:13:45 2022 +0000

    Generate illegal instruction fault if LWS syscall returns -EFAULT.
    
    2022-01-02  John David Anglin  <danglin@gcc.gnu.org>
    
    libgcc/ChangeLog:
    
            * config/pa/linux-atomic.c (_ASM_EFAULT): Define.
            (__kernel_cmpxchg): Nullify illegal iitlbp instruction if error
            return is not equal _ASM_EFAULT.
            (__kernel_cmpxchg2): Likewise.

Diff:
---
 libgcc/config/pa/linux-atomic.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/libgcc/config/pa/linux-atomic.c b/libgcc/config/pa/linux-atomic.c
index 500a3652499..e4d74b2d598 100644
--- a/libgcc/config/pa/linux-atomic.c
+++ b/libgcc/config/pa/linux-atomic.c
@@ -28,6 +28,8 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #define EBUSY   16
 #define ENOSYS 251 
 
+#define _ASM_EFAULT "-14"
+
 typedef unsigned char u8;
 typedef short unsigned int u16;
 #ifdef __LP64__
@@ -58,6 +60,8 @@ __kernel_cmpxchg (volatile void *mem, int oldval, int newval)
   register long lws_errno asm("r21");
   asm volatile (	"ble	0xb0(%%sr2, %%r0)	\n\t"
 			"ldi	%2, %%r20		\n\t"
+			"cmpiclr,<> " _ASM_EFAULT ", %%r21, %%r0\n\t"
+			"iitlbp %%r0,(%%sr0, %%r0)	\n\t"
 	: "=r" (lws_ret), "=r" (lws_errno)
 	: "i" (LWS_CAS), "r" (lws_mem), "r" (lws_old), "r" (lws_new)
 	: "r1", "r20", "r22", "r23", "r29", "r31", "memory"
@@ -84,6 +88,8 @@ __kernel_cmpxchg2 (volatile void *mem, const void *oldval, const void *newval,
   register long lws_errno asm("r21");
   asm volatile (	"ble	0xb0(%%sr2, %%r0)	\n\t"
 			"ldi	%6, %%r20		\n\t"
+			"cmpiclr,<> " _ASM_EFAULT ", %%r21, %%r0\n\t"
+			"iitlbp %%r0,(%%sr0, %%r0)	\n\t"
 	: "=r" (lws_ret), "=r" (lws_errno), "+r" (lws_mem),
 	  "+r" (lws_old), "+r" (lws_new), "+r" (lws_size)
 	: "i" (2)