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Detect kernel stack excursion into guard pages. Drop into KDB

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with a wired stack if this is found.

Mostly obtained from:  NetBSD
This commit is contained in:
Peter Grehan 2004-07-23 05:33:24 +00:00
parent a76b77653c
commit 2a1c4385c3
2 changed files with 72 additions and 10 deletions
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41
sys/powerpc/aim/trap_subr.S
View File

@ -228,6 +228,15 @@
mfsprg2 %r2; /* restore r2 & r3 */ \
mfsprg3 %r3
#ifdef KDB
/*
* Define the kdb debugger stack
*/
.data
GLOBAL(dbstk)
.space INTSTK+8 /* kdb stack */
#endif
/*
* This code gets copied to all the trap vectors
* (except ISI/DSI, ALI, and the interrupts)
@ -350,6 +359,33 @@ disitrap:
stw %r30,(PC_TEMPSAVE+CPUSAVE_DAR)(%r1)
stw %r31,(PC_TEMPSAVE+CPUSAVE_DSISR)(%r1)
#ifdef KDB
/* Try and detect a kernel stack overflow */
mfsrr1 %r31
mtcr %r31
bt 17,realtrap /* branch is user mode */
mfsprg1 %r31 /* get old SP */
sub. %r30,%r31,%r30 /* SP - DAR */
bge 1f
neg %r30,%r30 /* modulo value */
1: cmplwi %cr0,%r30,4096 /* is DAR within a page of SP? */
bge %cr0,realtrap /* no, too far away. */
/* Now convert this DSI into a DDB trap. */
GET_CPUINFO(%r1)
lwz %r30,(PC_DISISAVE+CPUSAVE_R28)(%r1) /* get r28 */
stw %r30,(PC_DBSAVE +CPUSAVE_R28)(%r1) /* save r28 */
lwz %r31,(PC_DISISAVE+CPUSAVE_R29)(%r1) /* get r29 */
stw %r31,(PC_DBSAVE +CPUSAVE_R29)(%r1) /* save r29 */
lwz %r30,(PC_DISISAVE+CPUSAVE_R30)(%r1) /* get r30 */
stw %r30,(PC_DBSAVE +CPUSAVE_R30)(%r1) /* save r30 */
lwz %r31,(PC_DISISAVE+CPUSAVE_R31)(%r1) /* get r31 */
stw %r31,(PC_DBSAVE +CPUSAVE_R31)(%r1) /* save r31 */
lis %r1,dbstk+INTSTK@ha /* get new SP */
addi %r1,%r1,dbstk+INTSTK@l
b dbtrap
#endif
/* XXX need stack probe here */
realtrap:
/* Test whether we already had PR set */
@ -460,11 +496,6 @@ dbleave:
/*
* In case of KDB we want a separate trap catcher for it
*/
.data
GLOBAL(dbstk)
.space INTSTK+8 /* kdb stack */
.text
.globl CNAME(dblow),CNAME(dbsize)
CNAME(dblow):
mtsprg1 %r1 /* save SP */

41
sys/powerpc/powerpc/trap_subr.S
View File

@ -228,6 +228,15 @@
mfsprg2 %r2; /* restore r2 & r3 */ \
mfsprg3 %r3
#ifdef KDB
/*
* Define the kdb debugger stack
*/
.data
GLOBAL(dbstk)
.space INTSTK+8 /* kdb stack */
#endif
/*
* This code gets copied to all the trap vectors
* (except ISI/DSI, ALI, and the interrupts)
@ -350,6 +359,33 @@ disitrap:
stw %r30,(PC_TEMPSAVE+CPUSAVE_DAR)(%r1)
stw %r31,(PC_TEMPSAVE+CPUSAVE_DSISR)(%r1)
#ifdef KDB
/* Try and detect a kernel stack overflow */
mfsrr1 %r31
mtcr %r31
bt 17,realtrap /* branch is user mode */
mfsprg1 %r31 /* get old SP */
sub. %r30,%r31,%r30 /* SP - DAR */
bge 1f
neg %r30,%r30 /* modulo value */
1: cmplwi %cr0,%r30,4096 /* is DAR within a page of SP? */
bge %cr0,realtrap /* no, too far away. */
/* Now convert this DSI into a DDB trap. */
GET_CPUINFO(%r1)
lwz %r30,(PC_DISISAVE+CPUSAVE_R28)(%r1) /* get r28 */
stw %r30,(PC_DBSAVE +CPUSAVE_R28)(%r1) /* save r28 */
lwz %r31,(PC_DISISAVE+CPUSAVE_R29)(%r1) /* get r29 */
stw %r31,(PC_DBSAVE +CPUSAVE_R29)(%r1) /* save r29 */
lwz %r30,(PC_DISISAVE+CPUSAVE_R30)(%r1) /* get r30 */
stw %r30,(PC_DBSAVE +CPUSAVE_R30)(%r1) /* save r30 */
lwz %r31,(PC_DISISAVE+CPUSAVE_R31)(%r1) /* get r31 */
stw %r31,(PC_DBSAVE +CPUSAVE_R31)(%r1) /* save r31 */
lis %r1,dbstk+INTSTK@ha /* get new SP */
addi %r1,%r1,dbstk+INTSTK@l
b dbtrap
#endif
/* XXX need stack probe here */
realtrap:
/* Test whether we already had PR set */
@ -460,11 +496,6 @@ dbleave:
/*
* In case of KDB we want a separate trap catcher for it
*/
.data
GLOBAL(dbstk)
.space INTSTK+8 /* kdb stack */
.text
.globl CNAME(dblow),CNAME(dbsize)
CNAME(dblow):
mtsprg1 %r1 /* save SP */