[v5,4/6] libelf: Expand ELF note printing

Commit Message

Jason Andryuk March 26, 2024, 9:38 p.m. UTC

The XEN_ELFNOTE_L1_MFN_VALID is an array of pairs of values, but it is
printed as:
(XEN) ELF: note: L1_MFN_VALID = 0

This is a limitation of only printing either string or numeric values.
Switch from the boolean to an enum which allows more flexibility in
printing the values.  Introduce ELFNOTE_NAME to only print the name
without a value like:
(XEN) ELF: note: L1_MFN_VALID

Details can optionally be printed for specific notes.

Signed-off-by: Jason Andryuk <[e-mail]>
Reviewed-by: Jan Beulich <[e-mail]>
---
v3:
Remove fatal size check
Don't print values - just the name for presence

v4:
Use switch
Always print newline for ELFNOTE_NAME

v5:
Add comment about newline printing
Add Jan's R-b
---
 xen/common/libelf/libelf-dominfo.c | 62 +++++++++++++++++++-----------
 1 file changed, 39 insertions(+), 23 deletions(-)

Comments

Jan Beulich March 27, 2024, 7:27 a.m. UTC | #1

On 26.03.2024 22:38, Jason Andryuk wrote:
> @@ -145,13 +150,20 @@ elf_errorstatus elf_xen_parse_note(struct elf_binary *elf,
>          elf_msg(elf, "ELF: note: %s = \"%s\"\n", note_desc[type].name, str);
>          parms->elf_notes[type].type = XEN_ENT_STR;
>          parms->elf_notes[type].data.str = str;
> -    }
> -    else
> -    {
> +        break;
> +
> +    case ELFNOTE_INT:
>          val = elf_note_numeric(elf, note);
>          elf_msg(elf, "ELF: note: %s = %#" PRIx64 "\n", note_desc[type].name, val);
>          parms->elf_notes[type].type = XEN_ENT_LONG;
>          parms->elf_notes[type].data.num = val;
> +        break;
> +
> +    case ELFNOTE_NAME:
> +        /* ELFNOTE_NAME has a newline printed at the end of the function to
> +         * optionally allow printing customized details. */
> +        elf_msg(elf, "ELF: note: %s", note_desc[type].name);
> +        break;

Well. I said "brief comment" for several reasons. One of them being that
it would best fit on a single line. Since now it doesn't, I have to point
out that this way comment style is violated.

/* NB: Newline emitted further down. */

?

Jan

Patch

diff --git a/xen/common/libelf/libelf-dominfo.c b/xen/common/libelf/libelf-dominfo.c
index a13a5e4db6..77bd582a37 100644
--- a/xen/common/libelf/libelf-dominfo.c
+++ b/xen/common/libelf/libelf-dominfo.c
@@ -101,26 +101,30 @@  elf_errorstatus elf_xen_parse_note(struct elf_binary *elf,
 /* *INDENT-OFF* */
     static const struct {
         const char *name;
-        bool str;
+        enum {
+            ELFNOTE_INT,
+            ELFNOTE_STRING,
+            ELFNOTE_NAME,
+        } type;
     } note_desc[] = {
-        [XEN_ELFNOTE_ENTRY] = { "ENTRY", 0},
-        [XEN_ELFNOTE_HYPERCALL_PAGE] = { "HYPERCALL_PAGE", 0},
-        [XEN_ELFNOTE_VIRT_BASE] = { "VIRT_BASE", 0},
-        [XEN_ELFNOTE_INIT_P2M] = { "INIT_P2M", 0},
-        [XEN_ELFNOTE_PADDR_OFFSET] = { "PADDR_OFFSET", 0},
-        [XEN_ELFNOTE_HV_START_LOW] = { "HV_START_LOW", 0},
-        [XEN_ELFNOTE_XEN_VERSION] = { "XEN_VERSION", 1},
-        [XEN_ELFNOTE_GUEST_OS] = { "GUEST_OS", 1},
-        [XEN_ELFNOTE_GUEST_VERSION] = { "GUEST_VERSION", 1},
-        [XEN_ELFNOTE_LOADER] = { "LOADER", 1},
-        [XEN_ELFNOTE_PAE_MODE] = { "PAE_MODE", 1},
-        [XEN_ELFNOTE_FEATURES] = { "FEATURES", 1},
-        [XEN_ELFNOTE_SUPPORTED_FEATURES] = { "SUPPORTED_FEATURES", 0},
-        [XEN_ELFNOTE_BSD_SYMTAB] = { "BSD_SYMTAB", 1},
-        [XEN_ELFNOTE_L1_MFN_VALID] = { "L1_MFN_VALID", false },
-        [XEN_ELFNOTE_SUSPEND_CANCEL] = { "SUSPEND_CANCEL", 0 },
-        [XEN_ELFNOTE_MOD_START_PFN] = { "MOD_START_PFN", 0 },
-        [XEN_ELFNOTE_PHYS32_ENTRY] = { "PHYS32_ENTRY", 0 },
+        [XEN_ELFNOTE_ENTRY] = { "ENTRY", ELFNOTE_INT },
+        [XEN_ELFNOTE_HYPERCALL_PAGE] = { "HYPERCALL_PAGE", ELFNOTE_INT },
+        [XEN_ELFNOTE_VIRT_BASE] = { "VIRT_BASE", ELFNOTE_INT },
+        [XEN_ELFNOTE_INIT_P2M] = { "INIT_P2M", ELFNOTE_INT },
+        [XEN_ELFNOTE_PADDR_OFFSET] = { "PADDR_OFFSET", ELFNOTE_INT },
+        [XEN_ELFNOTE_HV_START_LOW] = { "HV_START_LOW", ELFNOTE_INT },
+        [XEN_ELFNOTE_XEN_VERSION] = { "XEN_VERSION", ELFNOTE_STRING },
+        [XEN_ELFNOTE_GUEST_OS] = { "GUEST_OS", ELFNOTE_STRING },
+        [XEN_ELFNOTE_GUEST_VERSION] = { "GUEST_VERSION", ELFNOTE_STRING },
+        [XEN_ELFNOTE_LOADER] = { "LOADER", ELFNOTE_STRING },
+        [XEN_ELFNOTE_PAE_MODE] = { "PAE_MODE", ELFNOTE_STRING },
+        [XEN_ELFNOTE_FEATURES] = { "FEATURES", ELFNOTE_STRING },
+        [XEN_ELFNOTE_SUPPORTED_FEATURES] = { "SUPPORTED_FEATURES", ELFNOTE_INT },
+        [XEN_ELFNOTE_BSD_SYMTAB] = { "BSD_SYMTAB", ELFNOTE_STRING },
+        [XEN_ELFNOTE_L1_MFN_VALID] = { "L1_MFN_VALID", ELFNOTE_NAME },
+        [XEN_ELFNOTE_SUSPEND_CANCEL] = { "SUSPEND_CANCEL", ELFNOTE_INT },
+        [XEN_ELFNOTE_MOD_START_PFN] = { "MOD_START_PFN", ELFNOTE_INT },
+        [XEN_ELFNOTE_PHYS32_ENTRY] = { "PHYS32_ENTRY", ELFNOTE_INT },
     };
 /* *INDENT-ON* */
 
@@ -136,8 +140,9 @@  elf_errorstatus elf_xen_parse_note(struct elf_binary *elf,
         return 0;
     }
 
-    if ( note_desc[type].str )
+    switch ( note_desc[type].type )
     {
+    case ELFNOTE_STRING :
         str = elf_strval(elf, elf_note_desc(elf, note));
         if (str == NULL)
             /* elf_strval will mark elf broken if it fails so no need to log */
@@ -145,13 +150,20 @@  elf_errorstatus elf_xen_parse_note(struct elf_binary *elf,
         elf_msg(elf, "ELF: note: %s = \"%s\"\n", note_desc[type].name, str);
         parms->elf_notes[type].type = XEN_ENT_STR;
         parms->elf_notes[type].data.str = str;
-    }
-    else
-    {
+        break;
+
+    case ELFNOTE_INT:
         val = elf_note_numeric(elf, note);
         elf_msg(elf, "ELF: note: %s = %#" PRIx64 "\n", note_desc[type].name, val);
         parms->elf_notes[type].type = XEN_ENT_LONG;
         parms->elf_notes[type].data.num = val;
+        break;
+
+    case ELFNOTE_NAME:
+        /* ELFNOTE_NAME has a newline printed at the end of the function to
+         * optionally allow printing customized details. */
+        elf_msg(elf, "ELF: note: %s", note_desc[type].name);
+        break;
     }
     parms->elf_notes[type].name = note_desc[type].name;
 
@@ -218,6 +230,10 @@  elf_errorstatus elf_xen_parse_note(struct elf_binary *elf,
         parms->phys_entry = val;
         break;
     }
+
+    if ( note_desc[type].type == ELFNOTE_NAME)
+        elf_msg(elf, "\n");
+
     return 0;
 }