From: Willy Tarreau <w@1wt.eu>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: linux-kernel@vger.kernel.org, Willy Tarreau <w@1wt.eu>
Subject: [PATCH v2 17/22] tools/nolibc: add auxiliary vector retrieval for riscv
Date: Tue, 10 Jan 2023 08:24:29 +0100 [thread overview]
Message-ID: <20230110072434.3863-18-w@1wt.eu> (raw)
In-Reply-To: <20230110072434.3863-1-w@1wt.eu>
In the _start block we now iterate over envp to find the auxiliary
vector after the NULL. The pointer is saved into an _auxv variable
that is marked as weak so that it's accessible from multiple units.
It was tested on riscv64 only.
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
tools/include/nolibc/arch-riscv.h | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/tools/include/nolibc/arch-riscv.h b/tools/include/nolibc/arch-riscv.h
index 1608e6bd94b9..e197fcb10ac0 100644
--- a/tools/include/nolibc/arch-riscv.h
+++ b/tools/include/nolibc/arch-riscv.h
@@ -171,6 +171,7 @@ struct sys_stat_struct {
})
char **environ __attribute__((weak));
+const unsigned long *_auxv __attribute__((weak));
/* startup code */
void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) _start(void)
@@ -185,6 +186,15 @@ void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) _start(void)
"slli a2, a0, "PTRLOG"\n" // envp (a2) = SZREG*argc ...
"add a2, a2, "SZREG"\n" // + SZREG (skip null)
"add a2,a2,a1\n" // + argv
+
+ "add a3, a2, zero\n" // iterate a3 over envp to find auxv (after NULL)
+ "0:\n" // do {
+ "ld a4, 0(a3)\n" // a4 = *a3;
+ "add a3, a3, "SZREG"\n" // a3 += sizeof(void*);
+ "bne a4, zero, 0b\n" // } while (a4);
+ "lui a4, %hi(_auxv)\n" // a4 = &_auxv (high bits)
+ "sd a3, %lo(_auxv)(a4)\n" // store a3 into _auxv
+
"lui a3, %hi(environ)\n" // a3 = &environ (high bits)
"sd a2,%lo(environ)(a3)\n" // store envp(a2) into environ
"andi sp,a1,-16\n" // sp must be 16-byte aligned
--
2.17.5
next prev parent reply other threads:[~2023-01-10 7:26 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-10 7:24 [PATCH v2 00/22] nolibc: usability improvements (errno, environ, auxv) Willy Tarreau
2023-01-10 7:24 ` [PATCH v2 01/22] tools/nolibc: make compiler and assembler agree on the section around _start Willy Tarreau
2023-01-10 7:24 ` [PATCH v2 02/22] tools/nolibc: enable support for thumb1 mode for ARM Willy Tarreau
2023-01-10 7:24 ` [PATCH v2 03/22] tools/nolibc: support thumb mode with frame pointers on ARM Willy Tarreau
2023-01-10 7:24 ` [PATCH v2 04/22] tools/nolibc: remove local definitions of O_* flags for open/fcntl Willy Tarreau
2023-01-10 7:24 ` [PATCH v2 05/22] tools/nolibc: make errno a weak symbol instead of a static one Willy Tarreau
2023-01-10 7:24 ` [PATCH v2 06/22] tools/nolibc: export environ as a weak symbol on x86_64 Willy Tarreau
2023-01-10 7:24 ` [PATCH v2 07/22] tools/nolibc: export environ as a weak symbol on i386 Willy Tarreau
2023-01-10 7:24 ` [PATCH v2 08/22] tools/nolibc: export environ as a weak symbol on arm64 Willy Tarreau
2023-01-10 7:24 ` [PATCH v2 09/22] tools/nolibc: export environ as a weak symbol on arm Willy Tarreau
2023-01-10 7:24 ` [PATCH v2 10/22] tools/nolibc: export environ as a weak symbol on mips Willy Tarreau
2023-01-10 7:24 ` [PATCH v2 11/22] tools/nolibc: export environ as a weak symbol on riscv Willy Tarreau
2023-01-10 7:24 ` [PATCH v2 12/22] tools/nolibc: export environ as a weak symbol on s390 Willy Tarreau
2023-01-10 7:24 ` [PATCH v2 13/22] tools/nolibc: add auxiliary vector retrieval for i386 Willy Tarreau
2023-01-10 7:24 ` [PATCH v2 14/22] tools/nolibc: add auxiliary vector retrieval for x86_64 Willy Tarreau
2023-01-10 7:24 ` [PATCH v2 15/22] tools/nolibc: add auxiliary vector retrieval for arm64 Willy Tarreau
2023-01-10 7:24 ` [PATCH v2 16/22] tools/nolibc: add auxiliary vector retrieval for arm Willy Tarreau
2023-01-10 7:24 ` Willy Tarreau [this message]
2023-01-10 7:24 ` [PATCH v2 18/22] tools/nolibc: add auxiliary vector retrieval for mips Willy Tarreau
2023-01-10 7:24 ` [PATCH v2 19/22] tools/nolibc: add auxiliary vector retrieval for s390 Willy Tarreau
2023-01-10 7:24 ` [PATCH v2 20/22] nolibc/stdlib: Implement `getauxval(3)` function Willy Tarreau
2023-01-10 7:24 ` [PATCH v2 21/22] nolibc/sys: Implement `getpagesize(2)` function Willy Tarreau
2023-01-10 7:24 ` [PATCH v2 22/22] selftests/nolibc: Add `getpagesize(2)` selftest Willy Tarreau
2023-01-10 22:21 ` [PATCH v2 00/22] nolibc: usability improvements (errno, environ, auxv) Paul E. McKenney
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230110072434.3863-18-w@1wt.eu \
--to=w@1wt.eu \
--cc=linux-kernel@vger.kernel.org \
--cc=paulmck@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox