dtrace: support passing offset as arg0 to FBT return probes

FBT return probes pass the offset from the function start (in bytes)
as arg0.  To make that possible, we pass the offset value in the call
to fbt_add_probe.  For FBT entry probes we pass 0 (which is ignored).

This commit also ensures that we emulate the 'ret' instruction on the
return path.

Orabug: 25949086
Signed-off-by: Kris Van Hees <kris.van.hees@oracle.com>
Reviewed-by: Tomas Jedlicka <tomas.jedlicka@oracle.com>
Acked-by: Nick Alcock <nick.alcock@oracle.com>

diff --git a/dtrace/fbt_dev.c b/dtrace/fbt_dev.c
index 2d292a0a20e52e327971a3c548d5b6d69fea17ed..9d0ddd9487998abce0b3d1e8b13861cbc481bfa4 100644 (file)
--- a/dtrace/fbt_dev.c
+++ b/dtrace/fbt_dev.c
@@ -43,7 +43,8 @@ int                   fbt_probetab_size = FBT_PROBETAB_SIZE;
 int                    fbt_probetab_mask;
 
 static void *fbt_provide_probe(struct module *mp, char *func, int type, int
-                              stype, asm_instr_t *addr, void *pfbt)
+                              stype, asm_instr_t *addr, uintptr_t off,
+                              void *pfbt)
 {
        fbt_probe_t     *fbp;
        fbt_probe_t     *prev;
@@ -57,6 +58,7 @@ static void *fbt_provide_probe(struct module *mp, char *func, int type, int
                fbp->fbp_module = mp;
                fbp->fbp_loadcnt = 1; /* FIXME */
                fbp->fbp_primary = 1; /* FIXME */
+               fbp->fbp_roffset = off;
                fbp->fbp_patchpoint = addr;
                fbt_provide_probe_arch(fbp, type, stype);
                 fbp->fbp_hashnext = fbt_probetab[FBT_ADDR2NDX(addr)];
@@ -83,6 +85,7 @@ static void *fbt_provide_probe(struct module *mp, char *func, int type, int
                fbp->fbp_module = mp;
                fbp->fbp_loadcnt = 1; /* FIXME */
                fbp->fbp_primary = 1; /* FIXME */
+               fbp->fbp_roffset = off;
                fbp->fbp_patchpoint = addr;
                fbt_provide_probe_arch(fbp, type, stype);
                 fbp->fbp_hashnext = fbt_probetab[FBT_ADDR2NDX(addr)];

diff --git a/dtrace/fbt_x86_64.c b/dtrace/fbt_x86_64.c
index 9a873c7cec2be4c279e75f77a3ef7668a625c633..45eb7eb5ee7863efe71154f55225b4457dc3e6b1 100644 (file)
--- a/dtrace/fbt_x86_64.c
+++ b/dtrace/fbt_x86_64.c
@@ -41,9 +41,13 @@ static uint8_t fbt_invop(struct pt_regs *regs)
        for (; fbp != NULL; fbp = fbp->fbp_hashnext) {
                if ((uintptr_t)fbp->fbp_patchpoint == regs->ip) {
                        this_cpu_core->cpu_dtrace_regs = regs;
-
-                       dtrace_probe(fbp->fbp_id, regs->di, regs->si,
-                                    regs->dx, regs->cx, regs->r8);
+                       if (fbp->fbp_roffset == 0) {
+                               dtrace_probe(fbp->fbp_id, regs->di, regs->si,
+                                            regs->dx, regs->cx, regs->r8);
+                       } else {
+                               dtrace_probe(fbp->fbp_id, fbp->fbp_roffset,
+                                            regs->ax, 0, 0, 0);
+                       }
 
                        this_cpu_core->cpu_dtrace_regs = NULL;
 
@@ -58,7 +62,7 @@ void fbt_provide_probe_arch(fbt_probe_t *fbp, int type, int stype)
 {
        fbp->fbp_patchval = FBT_PATCHVAL;
        fbp->fbp_savedval = *fbp->fbp_patchpoint;
-       fbp->fbp_rval = type == FBT_ENTRY ? DTRACE_INVOP_MOV_RSP_RBP
+       fbp->fbp_rval = type == FBT_ENTRY ? DTRACE_INVOP_PUSH_BP
                                          : DTRACE_INVOP_RET;
 }