[Xen-devel] [PATCH MM-PART2 v2 08/19] xen/arm64: head: Move earlyprintk messages in .rodata.str

Julien Grall posted 19 patches 1 year, 11 months ago

[Xen-devel] [PATCH MM-PART2 v2 08/19] xen/arm64: head: Move earlyprintk messages in .rodata.str

Posted by Julien Grall 1 year, 11 months ago
At the moment, the earlyprintk messages are interleaved with the
instructions. This makes more difficult to read the objdump output.

Introduce a new macro to add a string in .rodata.str and use it for all
the earlyprintk messages.

Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Andrii Anisov <andrii_anisov@epam.com>

---

I haven't done a similar change in arm32 yet because the compiler will
throw an error when using 'adr' when load an address from a different
section (see A5-200 in ARM DDI 0406C.a for the technical reason).
The change is likely to be more elaborate.

    Changes in v2:
        - Add Andrii's reviewed-by
---
 xen/arch/arm/arm64/head.S       | 14 +++++---------
 xen/include/asm-arm/asm_defns.h |  5 +++++
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
index ad446e7345..b957eb90fb 100644
--- a/xen/arch/arm/arm64/head.S
+++ b/xen/arch/arm/arm64/head.S
@@ -81,13 +81,10 @@
 /* Macro to print a string to the UART, if there is one.
  * Clobbers x0-x3. */
 #ifdef CONFIG_EARLY_PRINTK
-#define PRINT(_s)       \
-        adr   x0, 98f ; \
-        bl    puts    ; \
-        b     99f     ; \
-98:     .asciz _s     ; \
-        .align 2      ; \
-99:
+#define PRINT(_s)           \
+        adr   x0, 98f ;     \
+        bl    puts    ;     \
+        RODATA_STR(98, _s)
 #else /* CONFIG_EARLY_PRINTK */
 #define PRINT(s)
 #endif /* !CONFIG_EARLY_PRINTK */
@@ -633,8 +630,7 @@ init_uart:
 #endif
         adr   x0, 1f
         b     puts
-1:      .asciz "- UART enabled -\r\n"
-        .align 4
+RODATA_STR(1, "- UART enabled -\r\n")
 
 /* Print early debug messages.
  * x0: Nul-terminated string to print.
diff --git a/xen/include/asm-arm/asm_defns.h b/xen/include/asm-arm/asm_defns.h
index 02be83e2b3..3f21def0ab 100644
--- a/xen/include/asm-arm/asm_defns.h
+++ b/xen/include/asm-arm/asm_defns.h
@@ -16,6 +16,11 @@
 # error "unknown ARM variant"
 #endif
 
+#define RODATA_STR(label, msg)                  \
+.pushsection .rodata.str, "aMS", %progbits, 1 ; \
+label:  .asciz msg;                             \
+.popsection
+
 #endif /* __ARM_ASM_DEFNS_H__ */
 /*
  * Local variables:
-- 
2.11.0


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