[PATCH 4.9 23/69] parisc: fix bugs in pa_memcpy

Greg Kroah-Hartman
2017-04-19T14:45:07Z

From: Mikulas Patocka <mpatocka@redhat.com>

commit 409c1b250e30ad0e48b4d15d7319b4e18c046c4f upstream.

The patch 554bfeceb8a22d448cd986fc9efce25e833278a1 ("parisc: Fix access
fault handling in pa_memcpy()") reimplements the pa_memcpy function.
Unfortunatelly, it makes the kernel unbootable. The crash happens in the
function ide_complete_cmd where memcpy is called with the same source
and destination address.

This patch fixes a few bugs in pa_memcpy:

* When jumping to .Lcopy_loop_16 for the first time, don't skip the
instruction "ldi 31,t0" (this bug made the kernel unbootable)
* Use the COND macro when comparing length, so that the comparison is
64-bit (a theoretical issue, in case the length is greater than
0xffffffff)
* Don't use the COND macro after the "extru" instruction (the PA-RISC
specification says that the upper 32-bits of extru result are undefined,
although they are set to zero in practice)
* Fix exception addresses in .Lcopy16_fault and .Lcopy8_fault
* Rename .Lcopy_loop_4 to .Lcopy_loop_8 (so that it is consistent with
.Lcopy8_fault)

Fixes: 554bfeceb8a2 ("parisc: Fix access fault handling in pa_memcpy()")
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/parisc/lib/lusercopy.S | 27 ++++++++++++++-------------
1 file changed, 14 insertions(+), 13 deletions(-)

--- a/arch/parisc/lib/lusercopy.S
+++ b/arch/parisc/lib/lusercopy.S
@@ -201,7 +201,7 @@ ENTRY_CFI(pa_memcpy)
add dst,len,end

/* short copy with less than 16 bytes? */
- cmpib,>>=,n 15,len,.Lbyte_loop
+ cmpib,COND(>>=),n 15,len,.Lbyte_loop

/* same alignment? */
xor src,dst,t0
@@ -216,7 +216,7 @@ ENTRY_CFI(pa_memcpy)
/* loop until we are 64-bit aligned */
.Lalign_loop64:
extru dst,31,3,t1
- cmpib,=,n 0,t1,.Lcopy_loop_16
+ cmpib,=,n 0,t1,.Lcopy_loop_16_start
20: ldb,ma 1(srcspc,src),t1
21: stb,ma t1,1(dstspc,dst)
b .Lalign_loop64
@@ -225,6 +225,7 @@ ENTRY_CFI(pa_memcpy)
ASM_EXCEPTIONTABLE_ENTRY(20b,.Lcopy_done)
ASM_EXCEPTIONTABLE_ENTRY(21b,.Lcopy_done)

+.Lcopy_loop_16_start:
ldi 31,t0
.Lcopy_loop_16:
cmpb,COND(>>=),n t0,len,.Lword_loop
@@ -267,7 +268,7 @@ ENTRY_CFI(pa_memcpy)
/* loop until we are 32-bit aligned */
.Lalign_loop32:
extru dst,31,2,t1
- cmpib,=,n 0,t1,.Lcopy_loop_4
+ cmpib,=,n 0,t1,.Lcopy_loop_8
20: ldb,ma 1(srcspc,src),t1
21: stb,ma t1,1(dstspc,dst)
b .Lalign_loop32
@@ -277,7 +278,7 @@ ENTRY_CFI(pa_memcpy)
ASM_EXCEPTIONTABLE_ENTRY(21b,.Lcopy_done)

-.Lcopy_loop_4:
+.Lcopy_loop_8:
cmpib,COND(>>=),n 15,len,.Lbyte_loop

10: ldw 0(srcspc,src),t1
@@ -299,7 +300,7 @@ ENTRY_CFI(pa_memcpy)
ASM_EXCEPTIONTABLE_ENTRY(16b,.Lcopy_done)
ASM_EXCEPTIONTABLE_ENTRY(17b,.Lcopy_done)

- b .Lcopy_loop_4
+ b .Lcopy_loop_8
ldo -16(len),len

.Lbyte_loop:
@@ -324,7 +325,7 @@ ENTRY_CFI(pa_memcpy)
.Lunaligned_copy:
/* align until dst is 32bit-word-aligned */
extru dst,31,2,t1
- cmpib,COND(=),n 0,t1,.Lcopy_dstaligned
+ cmpib,=,n 0,t1,.Lcopy_dstaligned
20: ldb 0(srcspc,src),t1
ldo 1(src),src
21: stb,ma t1,1(dstspc,dst)
@@ -362,7 +363,7 @@ ENTRY_CFI(pa_memcpy)
cmpiclr,<> 1,t0,%r0
b,n .Lcase1
.Lcase0:
- cmpb,= %r0,len,.Lcda_finish
+ cmpb,COND(=) %r0,len,.Lcda_finish
nop

1: ldw,ma 4(srcspc,src), a3
@@ -376,7 +377,7 @@ ENTRY_CFI(pa_memcpy)
1: ldw,ma 4(srcspc,src), a3
ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
ldo -1(len),len
- cmpb,=,n %r0,len,.Ldo0
+ cmpb,COND(=),n %r0,len,.Ldo0
.Ldo4:
1: ldw,ma 4(srcspc,src), a0
ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
@@ -402,7 +403,7 @@ ENTRY_CFI(pa_memcpy)
1: stw,ma t0, 4(dstspc,dst)
ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcopy_done)
ldo -4(len),len
- cmpb,<> %r0,len,.Ldo4
+ cmpb,COND(<>) %r0,len,.Ldo4
nop
.Ldo0:
shrpw a2, a3, %sar, t0
@@ -436,14 +437,14 @@ ENTRY_CFI(pa_memcpy)
/* fault exception fixup handlers: */
#ifdef CONFIG_64BIT
.Lcopy16_fault:
-10: b .Lcopy_done
- std,ma t1,8(dstspc,dst)
+ b .Lcopy_done
+10: std,ma t1,8(dstspc,dst)
ASM_EXCEPTIONTABLE_ENTRY(10b,.Lcopy_done)
#endif

.Lcopy8_fault:
-10: b .Lcopy_done
- stw,ma t1,4(dstspc,dst)
+ b .Lcopy_done
+10: stw,ma t1,4(dstspc,dst)
ASM_EXCEPTIONTABLE_ENTRY(10b,.Lcopy_done)

.exit