Attachment 149186 Details for Bug 230850 – elfutils-0.126 workaround using PTRACE_PEEKTEXT instead of `/proc/%d/mem'.

[patch] elfutils-0.126 workaround using PTRACE_PEEKTEXT instead of `/proc/%d/mem'.

elfutils-0.126-mem-ptrace.patch (text/plain), 2.96 KB, created by Jan Kratochvil on 2007-03-03 18:43:24 UTC

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Creator: Jan Kratochvil

Created: 2007-03-03 18:43:24 UTC

Size: 2.96 KB

patch

obsolete

>--- elfutils-0.126-orig/libdwfl/linux-proc-maps.c	2007-01-30 17:19:22.000000000 +0100
>+++ elfutils-0.126/libdwfl/linux-proc-maps.c	2007-03-03 19:33:33.000000000 +0100
>@@ -62,8 +62,18 @@
> #include <endian.h>
> 
> 
>+/* Value of 0 directs using PTRACE_PEEKTEXT workaround instead
>+   of `/proc/%d/mem' which is failing on some Linux kernels with ESRCH.  */
>+#define PROC_MEM_WORKS 0
>+
>+
> #define PROCMAPSFMT	"/proc/%d/maps"
>+#if PROC_MEM_WORKS
> #define PROCMEMFMT	"/proc/%d/mem"
>+#else
>+#include <sys/ptrace.h>
>+#include <sys/wait.h>
>+#endif
> #define PROCAUXVFMT	"/proc/%d/auxv"
> 
> 
>@@ -261,6 +271,8 @@ dwfl_linux_proc_report (Dwfl *dwfl, pid_
> }
> INTDEF (dwfl_linux_proc_report)
> 
>+#if PROC_MEM_WORKS
>+
> static ssize_t
> read_proc_memory (void *arg, void *data, GElf_Addr address,
> 		  size_t minread, size_t maxread)
>@@ -272,6 +284,57 @@ read_proc_memory (void *arg, void *data,
>   return nread;
> }
> 
>+#else /* !PROC_MEM_WORKS */
>+
>+struct read_ptrace_memory
>+  {
>+    int pid;
>+    unsigned ptraced:1;
>+  };
>+
>+static ssize_t
>+read_ptrace_memory (void *arg, void *data, GElf_Addr address,
>+		    size_t minread, size_t maxread)
>+{
>+  struct read_ptrace_memory *arg_typed = arg;
>+  const int pid = arg_typed->pid;
>+  ssize_t nread = 0;
>+  while ((size_t) nread < maxread)
>+    {
>+      long result;
>+      unsigned align = address & (sizeof (result) - 1);
>+      unsigned xfer_size = sizeof (result) - align;
>+      unsigned char *addr = (void *) (unsigned long) (address - align);
>+
>+      errno = 0;
>+      result = ptrace (PTRACE_PEEKTEXT, pid, addr, NULL);
>+
>+      if (!arg_typed->ptraced && errno == ESRCH)
>+        {
>+	  if (ptrace (PTRACE_ATTACH, pid, NULL, NULL) != 0)
>+	    break;
>+	  arg_typed->ptraced = 1;
>+	  if (waitpid (pid, NULL, 0) != pid)
>+	    break;
>+
>+	  errno = 0;
>+	  result = ptrace (PTRACE_PEEKTEXT, pid, addr, NULL);
>+	}
>+      if (errno != 0)
>+        break;
>+
>+      memcpy (data, (unsigned char *) &result + align, xfer_size);
>+      data += xfer_size;
>+      address += xfer_size;
>+      nread += xfer_size;
>+    }
>+  if (nread > 0 && (size_t) nread < minread)
>+    nread = 0;
>+  return nread;
>+}
>+
>+#endif /* !PROC_MEM_WORKS */
>+
> extern Elf *elf_from_remote_memory (GElf_Addr ehdr_vma,
> 				    GElf_Addr *loadbasep,
> 				    ssize_t (*read_memory) (void *arg,
>@@ -310,6 +373,8 @@ dwfl_linux_proc_find_elf (Dwfl_Module *m
>     {
>       /* Special case for in-memory ELF image.  */
> 
>+#if PROC_MEM_WORKS
>+
>       char *fname;
>       if (asprintf (&fname, PROCMEMFMT, pid) < 0)
> 	return -1;
>@@ -323,6 +388,23 @@ dwfl_linux_proc_find_elf (Dwfl_Module *m
> 
>       close (fd);
> 
>+#else /* !PROC_MEM_WORKS */
>+
>+      struct read_ptrace_memory arg_typed;
>+
>+      arg_typed.pid = pid;
>+      arg_typed.ptraced = 0;
>+      *elfp = elf_from_remote_memory (base, NULL, &read_ptrace_memory,
>+				      &arg_typed);
>+
>+      if (arg_typed.ptraced)
>+	{
>+	  if (ptrace (PTRACE_DETACH, pid, NULL, NULL) != 0)
>+	    return -1;
>+	}
>+
>+#endif /* !PROC_MEM_WORKS */
>+
>       *file_name = NULL;
>       return -1;
>     }

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Attachments on bug 230850: 149185 | 149186 | 149248 | 149350