[PATCH 2/8] gdbserver: Add thread parameter to linux_get_auxv and linux_get_hwcap

[Thiago Jung Bauermann <thiago.bauermann@linaro.org>]

This patch doesn't change gdbserver behaviour, but after later changes are
made it avoids a null pointer dereference when HWCAP needs to be obtained
for a specific process while current_thread is nullptr.

Fixing linux_read_auxv, linux_get_hwcap and linux_get_hwcap2 to take a
thread_info parameter seems more correct than setting current_thread in one
particular code path.

Changes are propagated to allow passing the thread parameter through the
call chain.
---
 gdbserver/linux-aarch64-low.cc |  6 +++---
 gdbserver/linux-arm-low.cc     |  2 +-
 gdbserver/linux-low.cc         | 20 +++++++++++---------
 gdbserver/linux-low.h          | 10 +++++-----
 gdbserver/linux-ppc-low.cc     |  6 +++---
 gdbserver/linux-s390-low.cc    |  2 +-
 gdbserver/netbsd-low.cc        |  4 ++--
 gdbserver/netbsd-low.h         |  4 ++--
 gdbserver/server.cc            |  2 +-
 gdbserver/target.cc            |  4 ++--
 gdbserver/target.h             |  4 ++--
 11 files changed, 33 insertions(+), 31 deletions(-)

diff --git a/gdbserver/linux-aarch64-low.cc b/gdbserver/linux-aarch64-low.cc
index db5086962612..5d4d667dfa42 100644
--- a/gdbserver/linux-aarch64-low.cc
+++ b/gdbserver/linux-aarch64-low.cc
@@ -826,9 +826,9 @@ aarch64_target::low_arch_setup ()
 
       features.vq = aarch64_sve_get_vq (tid);
       /* A-profile PAC is 64-bit only.  */
-      features.pauth = linux_get_hwcap (8) & AARCH64_HWCAP_PACA;
+      features.pauth = linux_get_hwcap (current_thread, 8) & AARCH64_HWCAP_PACA;
       /* A-profile MTE is 64-bit only.  */
-      features.mte = linux_get_hwcap2 (8) & HWCAP2_MTE;
+      features.mte = linux_get_hwcap2 (current_thread, 8) & HWCAP2_MTE;
       features.tls = true;
 
       current_process ()->tdesc = aarch64_linux_read_description (features);
@@ -3299,7 +3299,7 @@ aarch64_target::supports_memory_tagging ()
 #endif
     }
 
-  return (linux_get_hwcap2 (8) & HWCAP2_MTE) != 0;
+  return (linux_get_hwcap2 (current_thread, 8) & HWCAP2_MTE) != 0;
 }
 
 bool
diff --git a/gdbserver/linux-arm-low.cc b/gdbserver/linux-arm-low.cc
index ab6209a3abc8..d40ce412fe1c 100644
--- a/gdbserver/linux-arm-low.cc
+++ b/gdbserver/linux-arm-low.cc
@@ -958,7 +958,7 @@ get_next_pcs_syscall_next_pc (struct arm_get_next_pcs *self)
 static const struct target_desc *
 arm_read_description (void)
 {
-  unsigned long arm_hwcap = linux_get_hwcap (4);
+  unsigned long arm_hwcap = linux_get_hwcap (current_thread, 4);
 
   if (arm_hwcap & HWCAP_IWMMXT)
     return arm_linux_read_description (ARM_FP_TYPE_IWMMXT);
diff --git a/gdbserver/linux-low.cc b/gdbserver/linux-low.cc
index 2f71360d3bde..9034a1d8fabe 100644
--- a/gdbserver/linux-low.cc
+++ b/gdbserver/linux-low.cc
@@ -5486,12 +5486,12 @@ linux_process_target::supports_read_auxv ()
    to debugger memory starting at MYADDR.  */
 
 int
-linux_process_target::read_auxv (CORE_ADDR offset, unsigned char *myaddr,
-				 unsigned int len)
+linux_process_target::read_auxv (const thread_info *thread, CORE_ADDR offset,
+				 unsigned char *myaddr, unsigned int len)
 {
   char filename[PATH_MAX];
   int fd, n;
-  int pid = lwpid_of (current_thread);
+  int pid = lwpid_of (thread);
 
   xsnprintf (filename, sizeof filename, "/proc/%d/auxv", pid);
 
@@ -6912,14 +6912,16 @@ linux_get_pc_64bit (struct regcache *regcache)
 /* See linux-low.h.  */
 
 int
-linux_get_auxv (int wordsize, CORE_ADDR match, CORE_ADDR *valp)
+linux_get_auxv (const thread_info *thread, int wordsize, CORE_ADDR match,
+		CORE_ADDR *valp)
 {
   gdb_byte *data = (gdb_byte *) alloca (2 * wordsize);
   int offset = 0;
 
   gdb_assert (wordsize == 4 || wordsize == 8);
 
-  while (the_target->read_auxv (offset, data, 2 * wordsize) == 2 * wordsize)
+  while (the_target->read_auxv (thread, offset, data, 2 * wordsize)
+	 == 2 * wordsize)
     {
       if (wordsize == 4)
 	{
@@ -6949,20 +6951,20 @@ linux_get_auxv (int wordsize, CORE_ADDR match, CORE_ADDR *valp)
 /* See linux-low.h.  */
 
 CORE_ADDR
-linux_get_hwcap (int wordsize)
+linux_get_hwcap (const thread_info *thread, int wordsize)
 {
   CORE_ADDR hwcap = 0;
-  linux_get_auxv (wordsize, AT_HWCAP, &hwcap);
+  linux_get_auxv (thread, wordsize, AT_HWCAP, &hwcap);
   return hwcap;
 }
 
 /* See linux-low.h.  */
 
 CORE_ADDR
-linux_get_hwcap2 (int wordsize)
+linux_get_hwcap2 (const thread_info *thread, int wordsize)
 {
   CORE_ADDR hwcap2 = 0;
-  linux_get_auxv (wordsize, AT_HWCAP2, &hwcap2);
+  linux_get_auxv (thread, wordsize, AT_HWCAP2, &hwcap2);
   return hwcap2;
 }
 
diff --git a/gdbserver/linux-low.h b/gdbserver/linux-low.h
index 79be31b8f729..bd1ec31dc5a4 100644
--- a/gdbserver/linux-low.h
+++ b/gdbserver/linux-low.h
@@ -178,8 +178,8 @@ class linux_process_target : public process_stratum_target
 
   bool supports_read_auxv () override;
 
-  int read_auxv (CORE_ADDR offset, unsigned char *myaddr,
-		 unsigned int len) override;
+  int read_auxv (const thread_info *thread, CORE_ADDR offset,
+		 unsigned char *myaddr, unsigned int len) override;
 
   int insert_point (enum raw_bkpt_type type, CORE_ADDR addr,
 		    int size, raw_breakpoint *bp) override;
@@ -944,17 +944,17 @@ extern int have_ptrace_getregset;
    *VALP and return 1.  If not found or if there is an error, return
    0.  */
 
-int linux_get_auxv (int wordsize, CORE_ADDR match,
+int linux_get_auxv (const thread_info *thread, int wordsize, CORE_ADDR match,
 		    CORE_ADDR *valp);
 
 /* Fetch the AT_HWCAP entry from the auxv vector, where entries are length
    WORDSIZE.  If no entry was found, return zero.  */
 
-CORE_ADDR linux_get_hwcap (int wordsize);
+CORE_ADDR linux_get_hwcap (const thread_info *thread, int wordsize);
 
 /* Fetch the AT_HWCAP2 entry from the auxv vector, where entries are length
    WORDSIZE.  If no entry was found, return zero.  */
 
-CORE_ADDR linux_get_hwcap2 (int wordsize);
+CORE_ADDR linux_get_hwcap2 (const thread_info *thread, int wordsize);
 
 #endif /* GDBSERVER_LINUX_LOW_H */
diff --git a/gdbserver/linux-ppc-low.cc b/gdbserver/linux-ppc-low.cc
index 08824887003b..08608b2dcc38 100644
--- a/gdbserver/linux-ppc-low.cc
+++ b/gdbserver/linux-ppc-low.cc
@@ -894,8 +894,8 @@ ppc_target::low_arch_setup ()
 
   /* The value of current_process ()->tdesc needs to be set for this
      call.  */
-  ppc_hwcap = linux_get_hwcap (features.wordsize);
-  ppc_hwcap2 = linux_get_hwcap2 (features.wordsize);
+  ppc_hwcap = linux_get_hwcap (current_thread, features.wordsize);
+  ppc_hwcap2 = linux_get_hwcap2 (current_thread, features.wordsize);
 
   features.isa205 = ppc_linux_has_isa205 (ppc_hwcap);
 
@@ -1097,7 +1097,7 @@ is_elfv2_inferior (void)
   const struct target_desc *tdesc = current_process ()->tdesc;
   int wordsize = register_size (tdesc, 0);
 
-  if (!linux_get_auxv (wordsize, AT_PHDR, &phdr))
+  if (!linux_get_auxv (current_thread, wordsize, AT_PHDR, &phdr))
     return def_res;
 
   /* Assume ELF header is at the beginning of the page where program headers
diff --git a/gdbserver/linux-s390-low.cc b/gdbserver/linux-s390-low.cc
index 5adc28070574..0d01dffa64a4 100644
--- a/gdbserver/linux-s390-low.cc
+++ b/gdbserver/linux-s390-low.cc
@@ -592,7 +592,7 @@ s390_target::low_arch_setup ()
   /* Determine word size and HWCAP.  */
   int pid = pid_of (current_thread);
   int wordsize = s390_get_wordsize (pid);
-  unsigned long hwcap = linux_get_hwcap (wordsize);
+  unsigned long hwcap = linux_get_hwcap (current_thread, wordsize);
 
   /* Check whether the kernel supports extra register sets.  */
   int have_regset_last_break
diff --git a/gdbserver/netbsd-low.cc b/gdbserver/netbsd-low.cc
index f05bcd4e173f..71ac61e9dfbd 100644
--- a/gdbserver/netbsd-low.cc
+++ b/gdbserver/netbsd-low.cc
@@ -581,10 +581,10 @@ netbsd_read_auxv(pid_t pid, void *offs, void *addr, size_t len)
    to debugger memory starting at MYADDR.  */
 
 int
-netbsd_process_target::read_auxv (CORE_ADDR offset,
+netbsd_process_target::read_auxv (const thread_info *thread, CORE_ADDR offset,
 				  unsigned char *myaddr, unsigned int len)
 {
-  pid_t pid = pid_of (current_thread);
+  pid_t pid = pid_of (thread);
 
   return netbsd_read_auxv (pid, (void *) (intptr_t) offset, myaddr, len);
 }
diff --git a/gdbserver/netbsd-low.h b/gdbserver/netbsd-low.h
index 06b4fd613571..506329251eaf 100644
--- a/gdbserver/netbsd-low.h
+++ b/gdbserver/netbsd-low.h
@@ -77,8 +77,8 @@ class netbsd_process_target : public process_stratum_target
 
   bool supports_read_auxv () override;
 
-  int read_auxv (CORE_ADDR offset, unsigned char *myaddr,
-		 unsigned int len) override;
+  int read_auxv (const thread_info *thread, CORE_ADDR offset,
+		 unsigned char *myaddr, unsigned int len) override;
 
   bool supports_hardware_single_step () override;
 
diff --git a/gdbserver/server.cc b/gdbserver/server.cc
index c619206d5d2d..2d5cf6e8d8de 100644
--- a/gdbserver/server.cc
+++ b/gdbserver/server.cc
@@ -1443,7 +1443,7 @@ handle_qxfer_auxv (const char *annex,
   if (annex[0] != '\0' || current_thread == NULL)
     return -1;
 
-  return the_target->read_auxv (offset, readbuf, len);
+  return the_target->read_auxv (current_thread, offset, readbuf, len);
 }
 
 /* Handle qXfer:exec-file:read.  */
diff --git a/gdbserver/target.cc b/gdbserver/target.cc
index adcfe6e7bcc7..7ee18bde8635 100644
--- a/gdbserver/target.cc
+++ b/gdbserver/target.cc
@@ -344,8 +344,8 @@ process_stratum_target::supports_read_auxv ()
 }
 
 int
-process_stratum_target::read_auxv (CORE_ADDR offset, unsigned char *myaddr,
-				   unsigned int len)
+process_stratum_target::read_auxv (const thread_info *thread, CORE_ADDR offset,
+				   unsigned char *myaddr, unsigned int len)
 {
   gdb_assert_not_reached ("target op read_auxv not supported");
 }
diff --git a/gdbserver/target.h b/gdbserver/target.h
index 6c536a307786..cd6b2193a228 100644
--- a/gdbserver/target.h
+++ b/gdbserver/target.h
@@ -175,8 +175,8 @@ class process_stratum_target
   /* Read auxiliary vector data from the inferior process.
 
      Read LEN bytes at OFFSET into a buffer at MYADDR.  */
-  virtual int read_auxv (CORE_ADDR offset, unsigned char *myaddr,
-			 unsigned int len);
+  virtual int read_auxv (const thread_info *thread, CORE_ADDR offset,
+			 unsigned char *myaddr, unsigned int len);
 
   /* Returns true if GDB Z breakpoint type TYPE is supported, false
      otherwise.  The type is coded as follows: