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From: Yangyu Chen <cyy@cyyself.name>
To: libc-alpha@sourceware.org
Cc: Palmer Dabbelt <palmer@rivosinc.com>,
	Kito Cheng <kito.cheng@sifive.com>,
	Vincent Chen <vincent.chen@sifive.com>,
	Andreas Schwab <schwab@suse.de>, Yangyu Chen <cyy@cyyself.name>
Subject: [PATCH v2] RISC-V: Fix IFUNC resolver cannot access gp pointer
Date: Wed, 16 Oct 2024 01:01:02 +0800	[thread overview]
Message-ID: <tencent_71D182FBDA6E8E57B80731DD218D8D5C7C08@qq.com> (raw)

In some cases, an IFUNC resolver may need to access the gp pointer to
resolve the function address. Such an object may have l_relocated == 0.
In this case, the GP register will not be set up. Thus, the IFUNC
resolver cannot access the gp pointer. This patch fixes this issue by
relaxing the check of l_relocated in elf_machine_runtime_setup.

As for the original Bug 31317, since the static-linked executable has
already set up the gp pointer, we don't need to execute the code to set
up the gp pointer again. I have also reproduced and checked Bug 31317,
this patch can fix the issue.

Closes: BZ #32269
Fixes: 96d1b9ac23 ("RISC-V: Fix the static-PIE non-relocated object check")
Signed-off-by: Yangyu Chen <cyy@cyyself.name>
---
 sysdeps/riscv/dl-machine.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/sysdeps/riscv/dl-machine.h b/sysdeps/riscv/dl-machine.h
index b2f28697f7..10a36d6701 100644
--- a/sysdeps/riscv/dl-machine.h
+++ b/sysdeps/riscv/dl-machine.h
@@ -348,7 +348,8 @@ elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
       gotplt[1] = (ElfW(Addr)) l;
     }
 
-  if (l->l_type == lt_executable && l->l_relocated)
+#ifdef SHARED
+  if (l->l_type == lt_executable)
     {
       /* The __global_pointer$ may not be defined by the linker if the
 	 $gp register does not be used to access the global variable
@@ -368,6 +369,7 @@ elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
           : "r" (ref->st_value)
         );
     }
+#endif
 #endif
   return lazy;
 }
-- 
2.45.2


             reply	other threads:[~2024-10-15 17:01 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-10-15 17:01 Yangyu Chen [this message]
2024-10-30  2:58 ` Yangyu Chen
2024-10-30  3:10   ` Palmer Dabbelt
2024-10-30  6:50     ` Yangyu Chen
2024-10-30  7:36       ` Kito Cheng
2024-10-30  9:22         ` Florian Weimer
2024-10-30 10:26           ` Kito Cheng
2024-10-30 10:42             ` Florian Weimer
2024-10-30 10:48               ` Kito Cheng
2024-10-30 11:09                 ` Florian Weimer
2024-10-30 18:28                   ` Yangyu Chen
2024-10-31 10:07                     ` Kito Cheng
2024-10-31 10:32                     ` Florian Weimer
2024-10-31 10:35                       ` Yangyu Chen
2024-10-31 10:51                         ` Florian Weimer
2024-11-13 10:29     ` Yangyu Chen

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