From 1d00e5ce0fb069911c4b525ec38289fb5d9021b0 Mon Sep 17 00:00:00 2001
From: Paul Floyd <pjfloyd@wanadoo.fr>
Date: Sat, 18 Nov 2023 08:49:34 +0100
Subject: [PATCH 2/4] Bug 476548 - valgrind 3.22.0 fails on assertion when
 loading debuginfo file produced by mold

(cherry picked from commit 9ea4ae66707a4dcc6f4328e11911652e4418c585)

Upstream-Status: Backport [https://sourceware.org/git/?p=valgrind.git;a=commit;h=1d00e5ce0fb069911c4b525ec38289fb5d9021b0]
Signed-off-by: Khem Raj <raj.khem@gmail.com>
---
 NEWS                               |  2 ++
 coregrind/m_debuginfo/image.c      | 14 +++++++++
 coregrind/m_debuginfo/priv_image.h |  4 +++
 coregrind/m_debuginfo/readelf.c    | 49 ++++++++++++++++++++++++++++--
 4 files changed, 66 insertions(+), 3 deletions(-)

diff --git a/NEWS b/NEWS
index ee5b4ff11..6cd13429a 100644
--- a/NEWS
+++ b/NEWS
@@ -5,6 +5,8 @@ Branch 3.22
 
 The following bugs have been fixed or resolved on this branch.
 
+476548  valgrind 3.22.0 fails on assertion when loading debuginfo
+        file produced by mold
 476708  valgrind-monitor.py regular expressions should use raw strings
 
 To see details of a given bug, visit
diff --git a/coregrind/m_debuginfo/image.c b/coregrind/m_debuginfo/image.c
index 02e509071..445f95555 100644
--- a/coregrind/m_debuginfo/image.c
+++ b/coregrind/m_debuginfo/image.c
@@ -1221,6 +1221,20 @@ Int ML_(img_strcmp_c)(DiImage* img, DiOffT off1, const HChar* str2)
    }
 }
 
+Int ML_(img_strcmp_n)(DiImage* img, DiOffT off1, const HChar* str2, Word n)
+{
+   ensure_valid(img, off1, 1, "ML_(img_strcmp_c)");
+   while (n) {
+      UChar c1 = get(img, off1);
+      UChar c2 = *(const UChar*)str2;
+      if (c1 < c2) return -1;
+      if (c1 > c2) return 1;
+      if (c1 == 0) return 0;
+      off1++; str2++; --n;
+   }
+   return 0;
+}
+
 UChar ML_(img_get_UChar)(DiImage* img, DiOffT offset)
 {
    ensure_valid(img, offset, 1, "ML_(img_get_UChar)");
diff --git a/coregrind/m_debuginfo/priv_image.h b/coregrind/m_debuginfo/priv_image.h
index a49846f14..c91e49f01 100644
--- a/coregrind/m_debuginfo/priv_image.h
+++ b/coregrind/m_debuginfo/priv_image.h
@@ -115,6 +115,10 @@ Int ML_(img_strcmp)(DiImage* img, DiOffT off1, DiOffT off2);
    cast to HChar before comparison. */
 Int ML_(img_strcmp_c)(DiImage* img, DiOffT off1, const HChar* str2);
 
+/* Do strncmp of a C string in the image vs a normal one.  Chars are
+   cast to HChar before comparison. */
+Int ML_(img_strcmp_n)(DiImage* img, DiOffT off1, const HChar* str2, Word n);
+
 /* Do strlen of a C string in the image. */
 SizeT ML_(img_strlen)(DiImage* img, DiOffT off);
 
diff --git a/coregrind/m_debuginfo/readelf.c b/coregrind/m_debuginfo/readelf.c
index fb64ed976..46f8c8343 100644
--- a/coregrind/m_debuginfo/readelf.c
+++ b/coregrind/m_debuginfo/readelf.c
@@ -2501,8 +2501,7 @@ Bool ML_(read_elf_object) ( struct _DebugInfo* di )
             di->rodata_avma += inrw1->bias;
             di->rodata_bias = inrw1->bias;
             di->rodata_debug_bias = inrw1->bias;
-         }
-         else {
+         } else {
             BAD(".rodata");  /* should not happen? */
          }
          di->rodata_present = True;
@@ -2977,6 +2976,46 @@ Bool ML_(read_elf_object) ( struct _DebugInfo* di )
    return retval;
 }
 
+static void find_rodata(Word i, Word shnum, DiImage* dimg, struct _DebugInfo* di, DiOffT shdr_dioff,
+                        UWord shdr_dent_szB, DiOffT shdr_strtab_dioff, PtrdiffT rw_dbias)
+{
+   ElfXX_Shdr a_shdr;
+   ElfXX_Shdr a_extra_shdr;
+   ML_(img_get)(&a_shdr, dimg,
+                INDEX_BIS(shdr_dioff, i, shdr_dent_szB),
+                sizeof(a_shdr));
+   if (di->rodata_present &&
+       0 == ML_(img_strcmp_c)(dimg, shdr_strtab_dioff
+                                    + a_shdr.sh_name, ".rodata")) {
+      Word sh_size = a_shdr.sh_size;
+      Word j;
+      Word next_addr = a_shdr.sh_addr + a_shdr.sh_size;
+      for (j = i  + 1; j < shnum; ++j) {
+         ML_(img_get)(&a_extra_shdr, dimg,
+                      INDEX_BIS(shdr_dioff, j, shdr_dent_szB),
+                      sizeof(a_shdr));
+         if (0 == ML_(img_strcmp_n)(dimg, shdr_strtab_dioff
+                                             + a_extra_shdr.sh_name, ".rodata", 7)) {
+            if (a_extra_shdr.sh_addr ==
+                VG_ROUNDUP(next_addr, a_extra_shdr.sh_addralign)) {
+               sh_size = VG_ROUNDUP(sh_size, a_extra_shdr.sh_addralign) + a_extra_shdr.sh_size;
+            }
+            next_addr = a_extra_shdr.sh_addr + a_extra_shdr.sh_size;
+         } else {
+            break;
+         }
+      }
+      vg_assert(di->rodata_size == sh_size);
+      vg_assert(di->rodata_avma +  a_shdr.sh_addr + rw_dbias);
+      di->rodata_debug_svma = a_shdr.sh_addr;
+      di->rodata_debug_bias = di->rodata_bias +
+                             di->rodata_svma - di->rodata_debug_svma;
+      TRACE_SYMTAB("acquiring .rodata  debug svma = %#lx .. %#lx\n",
+                   di->rodata_debug_svma,
+                   di->rodata_debug_svma + di->rodata_size - 1);
+      TRACE_SYMTAB("acquiring .rodata debug bias = %#lx\n", (UWord)di->rodata_debug_bias);
+   }
+}
 Bool ML_(read_elf_debug) ( struct _DebugInfo* di )
 {
    Word     i, j;
@@ -3391,7 +3430,11 @@ Bool ML_(read_elf_debug) ( struct _DebugInfo* di )
             FIND(text,   rx)
             FIND(data,   rw)
             FIND(sdata,  rw)
-            FIND(rodata, rw)
+            // https://bugs.kde.org/show_bug.cgi?id=476548
+            // special handling for rodata as adjacent
+            // rodata sections may have been merged in ML_(read_elf_object)
+            //FIND(rodata, rw)
+            find_rodata(i, ehdr_dimg.e_shnum, dimg, di, shdr_dioff, shdr_dent_szB, shdr_strtab_dioff, rw_dbias);
             FIND(bss,    rw)
             FIND(sbss,   rw)
 
-- 
2.44.0

