[DTrace-devel] [PATCH] test: Switch kernel pointer in tracemem() test
Kris Van Hees
kris.van.hees at oracle.com
Tue May 23 04:37:40 UTC 2023
On Mon, May 22, 2023 at 03:28:08PM -0400, Eugene Loh via DTrace-devel wrote:
> ping
Reviewed-by: Kris Van Hees <kris.van.hees at oracle.com>
... with change below
>
> On 3/6/23 16:14, eugene.loh at oracle.com wrote:
> > From: Eugene Loh <eugene.loh at oracle.com>
> >
> > The tracemem() test dumped a portion of kernel memory, comparing
> > different tracemem() output for the same kernel memory for consistency.
> > Since it was looking at task_struct for the current thread, however,
> > the underlying data could conceivably change as the test ran, leading
> > to inconsistency and a false negative.
> >
> > Change the kernel memory to be the first 14 bytes of 'linux_banner,
'linux_banner -> `linux_banner
> > which should remain "Linux version ".
> >
> > Signed-off-by: Eugene Loh <eugene.loh at oracle.com>
> > ---
> > test/unittest/tracemem/tst.tracemem.d | 58 +++++--------------------
> > test/unittest/tracemem/tst.tracemem.r | 31 +++++++++----
> > test/unittest/tracemem/tst.tracemem.r.p | 30 -------------
> > 3 files changed, 34 insertions(+), 85 deletions(-)
> > delete mode 100755 test/unittest/tracemem/tst.tracemem.r.p
> >
> > diff --git a/test/unittest/tracemem/tst.tracemem.d b/test/unittest/tracemem/tst.tracemem.d
> > index 41440518..202fb514 100644
> > --- a/test/unittest/tracemem/tst.tracemem.d
> > +++ b/test/unittest/tracemem/tst.tracemem.d
> > @@ -13,53 +13,19 @@
> > #pragma D option quiet
> > -long long *p;
> > -
> > BEGIN {
> > - /* pick some pointer to kernel memory */
> > - p = (long long *) curthread;
> > -
> > - /* dump memory at this pointer */
> > - printf("%16.16x %16.16x\n", p[ 0], p[ 1]);
> > - printf("%16.16x %16.16x\n", p[ 2], p[ 3]);
> > - printf("%16.16x %16.16x\n", p[ 4], p[ 5]);
> > - printf("%16.16x %16.16x\n", p[ 6], p[ 7]);
> > - printf("%16.16x %16.16x\n", p[ 8], p[ 9]);
> > - printf("%16.16x %16.16x\n", p[10], p[11]);
> > - printf("%16.16x %16.16x\n", p[12], p[13]);
> > - printf("%16.16x %16.16x\n", p[14], p[15]);
> > - printf("%16.16x %16.16x\n", p[16], p[17]);
> > - printf("%16.16x %16.16x\n", p[18], p[19]);
> > - printf("%16.16x %16.16x\n", p[20], p[21]);
> > - printf("%16.16x %16.16x\n", p[22], p[23]);
> > - printf("%16.16x %16.16x\n", p[24], p[25]);
> > - printf("%16.16x %16.16x\n", p[26], p[27]);
> > - printf("%16.16x %16.16x\n", p[28], p[29]);
> > - printf("%16.16x %16.16x\n", p[30], p[31]);
> > -
> > - /* try tracemem() with this same pointer but various sizes */
> > -
> > - tracemem(p, 256); /* 256 bytes */
> > -
> > - tracemem(p, 256, -1); /* 256 bytes (arg2 < 0) */
> > -
> > - tracemem(p, 256, 0); /* 0 bytes */
> > -
> > - tracemem(p, 256, 32); /* 32 bytes */
> > -
> > - tracemem(p, 256, 64); /* 64 bytes */
> > -
> > - tracemem(p, 256, 128); /* 128 bytes */
> > -
> > - tracemem(p, 256, 256); /* 256 bytes */
> > -
> > - tracemem(p, 256, 320); /* 256 bytes (arg1 <= arg2) */
> > -
> > - tracemem(p, 256, (unsigned char) 0x80);
> > - /* 128 bytes */
> > -
> > - tracemem(p, 256, (signed char) 0x80);
> > - /* 256 bytes (arg2 < 0) */
> > + /* p = `linux_banner; */ /* first 14 chars are "Linux version " */
Why this comment? Why not uncomment it and use p in the tracemem() actions
below?
> > +
> > + /* try tracemem() with various sizes */
> > +
> > + tracemem(`linux_banner, 14); /* "Linux version ": 14 bytes */
> > + tracemem(`linux_banner, 14, -1); /* "Linux version ": 14 bytes (arg2 < 0) */
> > + tracemem(`linux_banner, 14, 0); /* 0 bytes */
> > + tracemem(`linux_banner, 14, 2); /* "Li" : 2 bytes */
> > + tracemem(`linux_banner, 14, 7); /* "Linux v" : 7 bytes */
> > + tracemem(`linux_banner, 14, 12); /* "Linux versio" : 12 bytes */
> > + tracemem(`linux_banner, 14, 14); /* "Linux version ": 14 bytes */
> > + tracemem(`linux_banner, 14, 15); /* "Linux version ": 14 bytes (arg1 <= arg2) */
> > exit(0);
> > }
> > diff --git a/test/unittest/tracemem/tst.tracemem.r b/test/unittest/tracemem/tst.tracemem.r
> > index 1b24115f..2952158d 100644
> > --- a/test/unittest/tracemem/tst.tracemem.r
> > +++ b/test/unittest/tracemem/tst.tracemem.r
> > @@ -1,9 +1,22 @@
> > -256 bytes
> > -256 bytes
> > -32 bytes
> > -64 bytes
> > -128 bytes
> > -256 bytes
> > -256 bytes
> > -128 bytes
> > -256 bytes
> > +
> > + 0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
> > + 0: 4c 69 6e 75 78 20 76 65 72 73 69 6f 6e 20 Linux version
> > +
> > + 0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
> > + 0: 4c 69 6e 75 78 20 76 65 72 73 69 6f 6e 20 Linux version
> > +
> > + 0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
> > + 0: 4c 69 Li
> > +
> > + 0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
> > + 0: 4c 69 6e 75 78 20 76 Linux v
> > +
> > + 0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
> > + 0: 4c 69 6e 75 78 20 76 65 72 73 69 6f Linux versio
> > +
> > + 0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
> > + 0: 4c 69 6e 75 78 20 76 65 72 73 69 6f 6e 20 Linux version
> > +
> > + 0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
> > + 0: 4c 69 6e 75 78 20 76 65 72 73 69 6f 6e 20 Linux version
> > +
> > diff --git a/test/unittest/tracemem/tst.tracemem.r.p b/test/unittest/tracemem/tst.tracemem.r.p
> > deleted file mode 100755
> > index 3f34b26b..00000000
> > --- a/test/unittest/tracemem/tst.tracemem.r.p
> > +++ /dev/null
> > @@ -1,30 +0,0 @@
> > -#!/usr/bin/gawk -f
> > -
> > -# read data against which we will check tracemem() results
> > -BEGIN {
> > - n = 0; # count check results
> > - m = 0; # count tracemem() results
> > -}
> > -NF == 2 {
> > - check[n] = $1; n++;
> > - check[n] = $2; n++;
> > - next;
> > -}
> > -
> > -# if we have a blank line, report number of bytes compared, if any
> > -NF == 0 && m > 0 { print 8 * m, "bytes" }
> > -
> > -# restart counting tracemem() output
> > -NF == 0 { m = 0; next; }
> > -
> > -# comparison function
> > -function mycomp(expect, actual) {
> > - if ( expect != actual )
> > - print "ERROR: expect", expect, "actual", actual;
> > -}
> > -
> > -# tracemem output has two sets of 8 bytes each; reverse bytes for comparison
> > -/:/ {
> > - mycomp( check[m++], $9$8$7$6$5$4$3$2);
> > - mycomp( check[m++], $17$16$15$14$13$12$11$10);
> > -}
>
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