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Differential D39595 Diff 122636 lib/libpmcstat/libpmcstat_process.c

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lib/libpmcstat/libpmcstat_process.c

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#include "libpmcstat.h" #include "libpmcstat.h"
/* /*
* Associate an AOUT image with a process. * Associate an AOUT image with a process.
*/ */
void void
pmcstat_process_aout_exec(struct pmcstat_process *pp, pmcstat_process_aout_exec(struct pmcstat_process *pp,
struct pmcstat_image *image, uintfptr_t entryaddr) struct pmcstat_image *image, uintptr_t baseaddr)
{ {
(void) pp; (void) pp;
(void) image; (void) image;
(void) entryaddr; (void) baseaddr;
/* TODO Implement a.out handling */ /* TODO Implement a.out handling */
emasteUnsubmitted
Not Done
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I think we could just delete this function

emaste: I think we could just delete this function
} }
/* /*
* Associate an ELF image with a process. * Associate an ELF image with a process.
*/ */
void void
pmcstat_process_elf_exec(struct pmcstat_process *pp, pmcstat_process_elf_exec(struct pmcstat_process *pp,
struct pmcstat_image *image, uintfptr_t entryaddr, struct pmcstat_image *image, uintptr_t baseaddr, uintptr_t dynaddr,
struct pmcstat_args *args, struct pmc_plugins *plugins, struct pmcstat_args *args, struct pmc_plugins *plugins,
struct pmcstat_stats *pmcstat_stats) struct pmcstat_stats *pmcstat_stats)
{ {
uintmax_t libstart;
struct pmcstat_image *rtldimage; struct pmcstat_image *rtldimage;
assert(image->pi_type == PMCSTAT_IMAGE_ELF32 || assert(image->pi_type == PMCSTAT_IMAGE_ELF32 ||
image->pi_type == PMCSTAT_IMAGE_ELF64); image->pi_type == PMCSTAT_IMAGE_ELF64);
/* Create a map entry for the base executable. */ /*
pmcstat_image_link(pp, image, image->pi_vaddr); * The exact address where the executable gets mapped in will vary for
* PIEs. The dynamic address recorded at process exec time corresponds
* to the address where the executable's file object had been mapped to.
*/
pmcstat_image_link(pp, image, image->pi_vaddr + dynaddr);
jhbUnsubmitted
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Presumably pi_vaddr is always 0 for PIEs?

jhb: Presumably pi_vaddr is always 0 for PIEs?
jrtc27AuthorUnsubmitted
Done
Inline Actions

Yes. If you have a non-zero base address for ET_DYN then the kernel will honour it.

jrtc27: Yes. If you have a non-zero base address for ET_DYN then the kernel will honour it.
/* /*
* For dynamically linked executables we need to determine * For dynamically linked executables we need to determine
* where the dynamic linker was mapped to for this process, * where the dynamic linker was mapped to for this process,
* Subsequent executable objects that are mapped in by the * Subsequent executable objects that are mapped in by the
* dynamic linker will be tracked by log events of type * dynamic linker will be tracked by log events of type
* PMCLOG_TYPE_MAP_IN. * PMCLOG_TYPE_MAP_IN.
*/ */
if (image->pi_isdynamic) { if (image->pi_isdynamic) {
/* /*
* The runtime loader gets loaded just after the maximum * The runtime loader gets loaded just after the maximum
* possible heap address. Like so: * possible heap address. Like so:
* *
* [ TEXT DATA BSS HEAP -->*RTLD SHLIBS <--STACK] * [ TEXT DATA BSS HEAP -->*RTLD SHLIBS <--STACK]
* ^ ^ * ^ ^
* 0 VM_MAXUSER_ADDRESS * 0 VM_MAXUSER_ADDRESS
* *
* The exact address where the loader gets mapped in * The exact address where the loader gets mapped in
* will vary according to the size of the executable * will vary according to the size of the executable
* and the limits on the size of the process'es data * and the limits on the size of the process'es data
* segment at the time of exec(). The entry address * segment at the time of exec(). The base address
* recorded at process exec time corresponds to the * recorded at process exec time corresponds to the
* 'start' address inside the dynamic linker. From * address where the runtime loader's file object had
* this we can figure out the address where the * been mapped to.
* runtime loader's file object had been mapped to.
*/ */
rtldimage = pmcstat_image_from_path(image->pi_dynlinkerpath, rtldimage = pmcstat_image_from_path(image->pi_dynlinkerpath,
0, args, plugins); 0, args, plugins);
if (rtldimage == NULL) { if (rtldimage == NULL) {
warnx("WARNING: Cannot find image for \"%s\".", warnx("WARNING: Cannot find image for \"%s\".",
pmcstat_string_unintern(image->pi_dynlinkerpath)); pmcstat_string_unintern(image->pi_dynlinkerpath));
pmcstat_stats->ps_exec_errors++; pmcstat_stats->ps_exec_errors++;
return; return;
} }
if (rtldimage->pi_type == PMCSTAT_IMAGE_UNKNOWN) if (rtldimage->pi_type == PMCSTAT_IMAGE_UNKNOWN)
pmcstat_image_get_elf_params(rtldimage, args); pmcstat_image_get_elf_params(rtldimage, args);
if (rtldimage->pi_type != PMCSTAT_IMAGE_ELF32 && if (rtldimage->pi_type != PMCSTAT_IMAGE_ELF32 &&
rtldimage->pi_type != PMCSTAT_IMAGE_ELF64) { rtldimage->pi_type != PMCSTAT_IMAGE_ELF64) {
warnx("WARNING: rtld not an ELF object \"%s\".", warnx("WARNING: rtld not an ELF object \"%s\".",
pmcstat_string_unintern(image->pi_dynlinkerpath)); pmcstat_string_unintern(image->pi_dynlinkerpath));
return; return;
} }
libstart = entryaddr - rtldimage->pi_entry; pmcstat_image_link(pp, rtldimage, baseaddr);
jhbUnsubmitted
Not Done
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Presumably rtld is always PIE which is why rtldimage->pi_vaddr can be ignored here?

jhb: Presumably rtld is always PIE which is why rtldimage->pi_vaddr can be ignored here?
jrtc27AuthorUnsubmitted
Done
Inline Actions

In effect (otherwise the existing code wouldn't have worked; it relied on pi_entry being the offset of the entry point in order to turn entryaddr back into baseaddr). Really it's a shared library that has an entry point (I guess a static PIE in effect, even?).

jrtc27: In effect (otherwise the existing code wouldn't have worked; it relied on pi_entry being the…
pmcstat_image_link(pp, rtldimage, libstart);
} }
} }
/* /*
* Associate an image and a process. * Associate an image and a process.
*/ */
void void
pmcstat_process_exec(struct pmcstat_process *pp, pmcstat_process_exec(struct pmcstat_process *pp,
pmcstat_interned_string path, uintfptr_t entryaddr, pmcstat_interned_string path, uintptr_t baseaddr, uintptr_t dynaddr,
struct pmcstat_args *args, struct pmc_plugins *plugins, struct pmcstat_args *args, struct pmc_plugins *plugins,
struct pmcstat_stats *pmcstat_stats) struct pmcstat_stats *pmcstat_stats)
{ {
struct pmcstat_image *image; struct pmcstat_image *image;
if ((image = pmcstat_image_from_path(path, 0, if ((image = pmcstat_image_from_path(path, 0,
args, plugins)) == NULL) { args, plugins)) == NULL) {
pmcstat_stats->ps_exec_errors++; pmcstat_stats->ps_exec_errors++;
return; return;
} }
if (image->pi_type == PMCSTAT_IMAGE_UNKNOWN) if (image->pi_type == PMCSTAT_IMAGE_UNKNOWN)
pmcstat_image_determine_type(image, args); pmcstat_image_determine_type(image, args);
assert(image->pi_type != PMCSTAT_IMAGE_UNKNOWN); assert(image->pi_type != PMCSTAT_IMAGE_UNKNOWN);
switch (image->pi_type) { switch (image->pi_type) {
case PMCSTAT_IMAGE_ELF32: case PMCSTAT_IMAGE_ELF32:
case PMCSTAT_IMAGE_ELF64: case PMCSTAT_IMAGE_ELF64:
pmcstat_stats->ps_exec_elf++; pmcstat_stats->ps_exec_elf++;
pmcstat_process_elf_exec(pp, image, entryaddr, pmcstat_process_elf_exec(pp, image, baseaddr, dynaddr,
args, plugins, pmcstat_stats); args, plugins, pmcstat_stats);
break; break;
case PMCSTAT_IMAGE_AOUT: case PMCSTAT_IMAGE_AOUT:
pmcstat_stats->ps_exec_aout++; pmcstat_stats->ps_exec_aout++;
pmcstat_process_aout_exec(pp, image, entryaddr); pmcstat_process_aout_exec(pp, image, baseaddr);
break; break;
case PMCSTAT_IMAGE_INDETERMINABLE: case PMCSTAT_IMAGE_INDETERMINABLE:
pmcstat_stats->ps_exec_indeterminable++; pmcstat_stats->ps_exec_indeterminable++;
break; break;
default: default:
err(EX_SOFTWARE, err(EX_SOFTWARE,
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