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Zend, ext/opcache: use PR_SET_VMA_ANON_NAME (Linux 5.17) #8234

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Merged
merged 1 commit into from
Jun 20, 2022
Merged

Zend, ext/opcache: use PR_SET_VMA_ANON_NAME (Linux 5.17) #8234

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3 changes: 3 additions & 0 deletions Zend/zend_alloc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,7 @@
#include "zend_operators.h"
#include "zend_multiply.h"
#include "zend_bitset.h"
#include "zend_mmap.h"
#include <signal.h>

#ifdef HAVE_UNISTD_H
Expand Down Expand Up @@ -475,6 +476,7 @@ static void *zend_mm_mmap(size_t size)
#endif
ptr = mmap(NULL, size, PROT_READ | PROT_WRITE, mflags, fd, 0);
if (ptr != MAP_FAILED) {
zend_mmap_set_name(ptr, size, "zend_alloc");
return ptr;
}
}
Expand All @@ -488,6 +490,7 @@ static void *zend_mm_mmap(size_t size)
#endif
return NULL;
}
zend_mmap_set_name(ptr, size, "zend_alloc");
return ptr;
#endif
}
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3 changes: 3 additions & 0 deletions Zend/zend_fibers.c
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Expand Up @@ -24,6 +24,7 @@
#include "zend_exceptions.h"
#include "zend_builtin_functions.h"
#include "zend_observer.h"
#include "zend_mmap.h"

#include "zend_fibers.h"
#include "zend_fibers_arginfo.h"
Expand Down Expand Up @@ -211,6 +212,8 @@ static zend_fiber_stack *zend_fiber_stack_allocate(size_t size)
return NULL;
}

zend_mmap_set_name(pointer, alloc_size, "zend_fiber_stack");

# if ZEND_FIBER_GUARD_PAGES
if (mprotect(pointer, ZEND_FIBER_GUARD_PAGES * page_size, PROT_NONE) < 0) {
zend_throw_exception_ex(NULL, 0, "Fiber stack protect failed: mprotect failed: %s (%d)", strerror(errno), errno);
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44 changes: 44 additions & 0 deletions Zend/zend_mmap.h
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@@ -0,0 +1,44 @@
/*
+----------------------------------------------------------------------+
| This source file is subject to version 2.00 of the Zend license, |
| that is bundled with this package in the file LICENSE, and is |
| available through the world-wide-web at the following url: |
| http://www.zend.com/license/2_00.txt. |
| If you did not receive a copy of the Zend license and are unable to |
| obtain it through the world-wide-web, please send a note to |
| license@zend.com so we can mail you a copy immediately. |
+----------------------------------------------------------------------+
| Authors: Max Kellermann <max.kellermann@ionos.com> |
+----------------------------------------------------------------------+
*/

#ifndef ZEND_MMAP_H
#define ZEND_MMAP_H

#include "zend_portability.h"

#ifdef __linux__
# include <sys/prctl.h>

/* fallback definitions if our libc is older than the kernel */
# ifndef PR_SET_VMA
# define PR_SET_VMA 0x53564d41
# endif
# ifndef PR_SET_VMA_ANON_NAME
# define PR_SET_VMA_ANON_NAME 0
# endif
#endif // __linux__

/**
* Set a name for the specified memory area.
*
* This feature requires Linux 5.17.
*/
static zend_always_inline void zend_mmap_set_name(const void *start, size_t len, const char *name)
{
#ifdef __linux__
prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, (unsigned long)start, len, (unsigned long)name);
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Is it safe to call prctl with options unsupported by the kernel?

https://github.com/torvalds/linux/blob/7403e6d8263937dea206dd201fed1ceed190ca18/kernel/sys.c#L2615

Looks like the answer is yes and it'll just return -1 but the docs aren't very clear so I thought I'd ask.

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Is it safe to call prctl with options unsupported by the kernel?

yes,, it will just return -1;

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Not sure it warrants a new file for that.

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I made this a new file to reduce header dependencies, to avoid adding a dependency to sys/prctl.h to almost all sources.
The PHP code base is currently pretty clumsy about header dependencies; you have catch-all headers like zend_portability.h. I don't like that.
My coding style is to have many small and domain-specific headers with only the bare minimum of header-including-other-header. This speeds up compile times and improves code correctness.
But ... since this is not my project, I'll accept any style you desire, and will amend this PR.

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@devnexen devnexen Jun 18, 2022 •
edited
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I feel if it had more it maybe it would worth it but that s personal opinion tough, other members might think differently. But what do you make about the other points I made below ?

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I would generally agree that many of our files are too big and mixing too much code of different purposes can make it hard to understand the original intention of the file. But I don't know how the other maintainers feel.

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Same sentiment here

#endif
}

#endif /* ZEND_MMAP_H */
3 changes: 3 additions & 0 deletions ext/opcache/ZendAccelerator.c
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Expand Up @@ -34,6 +34,7 @@
#include "zend_vm.h"
#include "zend_inheritance.h"
#include "zend_exceptions.h"
#include "zend_mmap.h"
#include "main/php_main.h"
#include "main/SAPI.h"
#include "main/php_streams.h"
Expand Down Expand Up @@ -2987,6 +2988,8 @@ static int accel_remap_huge_pages(void *start, size_t size, size_t real_size, co
# endif
}

zend_mmap_set_name(start, size, "zend_huge_code_pages");

if (ret == start) {
memcpy(start, mem, real_size);
mprotect(start, size, PROT_READ | PROT_EXEC);
Expand Down
6 changes: 5 additions & 1 deletion ext/opcache/jit/zend_jit_perf_dump.c
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Expand Up @@ -46,6 +46,7 @@ extern unsigned int thr_self(void);
#endif

#include "zend_elf.h"
#include "zend_mmap.h"

/*
* 1) Profile using perf-<pid>.map
Expand Down Expand Up @@ -171,8 +172,9 @@ static void zend_jit_perf_jitdump_open(void)
return;
}

const size_t page_size = sysconf(_SC_PAGESIZE);
jitdump_mem = mmap(NULL,
sysconf(_SC_PAGESIZE),
page_size,
PROT_READ|PROT_EXEC,
MAP_PRIVATE, jitdump_fd, 0);

Expand All @@ -182,6 +184,8 @@ static void zend_jit_perf_jitdump_open(void)
return;
}

zend_mmap_set_name(jitdump_mem, page_size, "zend_jitdump");

memset(&jit_hdr, 0, sizeof(jit_hdr));
jit_hdr.magic = ZEND_PERF_JITDUMP_HEADER_MAGIC;
jit_hdr.version = ZEND_PERF_JITDUMP_HEADER_VERSION;
Expand Down