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authorDmitry Safonov <dima@arista.com>2020-06-09 07:30:07 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-09 19:39:10 +0300
commit5489ab50c22771ddcad014968141b0d104d650a3 (patch)
treeda45382c2f04f70bf5f8abecb8132baf70f38874 /arch/arm/lib
parent8ca4d19932a5649930db29202b285d8e4e96a98a (diff)
downloadlinux-5489ab50c22771ddcad014968141b0d104d650a3.tar.xz
arm/asm: add loglvl to c_backtrace()
Currently, the log-level of show_stack() depends on a platform realization. It creates situations where the headers are printed with lower log level or higher than the stacktrace (depending on a platform or user). Furthermore, it forces the logic decision from user to an architecture side. In result, some users as sysrq/kdb/etc are doing tricks with temporary rising console_loglevel while printing their messages. And in result it not only may print unwanted messages from other CPUs, but also omit printing at all in the unlucky case where the printk() was deferred. Introducing log-level parameter and KERN_UNSUPPRESSED [1] seems an easier approach than introducing more printk buffers. Also, it will consolidate printings with headers. Add log level argument to c_backtrace() as a preparation for introducing show_stack_loglvl(). [1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/T/#u Signed-off-by: Dmitry Safonov <dima@arista.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Will Deacon <will@kernel.org> Link: http://lkml.kernel.org/r/20200418201944.482088-5-dima@arista.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/arm/lib')
-rw-r--r--arch/arm/lib/backtrace-clang.S9
-rw-r--r--arch/arm/lib/backtrace.S14
2 files changed, 17 insertions, 6 deletions
diff --git a/arch/arm/lib/backtrace-clang.S b/arch/arm/lib/backtrace-clang.S
index 2ff375144b55..6174c45f53a5 100644
--- a/arch/arm/lib/backtrace-clang.S
+++ b/arch/arm/lib/backtrace-clang.S
@@ -17,6 +17,7 @@
#define sv_pc r6
#define mask r7
#define sv_lr r8
+#define loglvl r9
ENTRY(c_backtrace)
@@ -99,6 +100,7 @@ ENDPROC(c_backtrace)
@ to ensure 8 byte alignment
movs frame, r0 @ if frame pointer is zero
beq no_frame @ we have no stack frames
+ mov loglvl, r2
tst r1, #0x10 @ 26 or 32-bit mode?
moveq mask, #0xfc000003
movne mask, #0 @ mask for 32-bit
@@ -167,6 +169,7 @@ finished_setup:
mov r1, sv_lr
mov r2, frame
bic r1, r1, mask @ mask PC/LR for the mode
+ mov r3, loglvl
bl dump_backtrace_entry
/*
@@ -183,6 +186,7 @@ finished_setup:
ldr r0, [frame] @ locals are stored in
@ the preceding frame
subeq r0, r0, #4
+ mov r2, loglvl
bleq dump_backtrace_stm @ dump saved registers
/*
@@ -196,7 +200,8 @@ finished_setup:
bhi for_each_frame
1006: adr r0, .Lbad
- mov r1, frame
+ mov r1, loglvl
+ mov r2, frame
bl printk
no_frame: ldmfd sp!, {r4 - r9, fp, pc}
ENDPROC(c_backtrace)
@@ -209,7 +214,7 @@ ENDPROC(c_backtrace)
.long 1005b, 1006b
.popsection
-.Lbad: .asciz "Backtrace aborted due to bad frame pointer <%p>\n"
+.Lbad: .asciz "%sBacktrace aborted due to bad frame pointer <%p>\n"
.align
.Lopcode: .word 0xe92d4800 >> 11 @ stmfd sp!, {... fp, lr}
.word 0x0b000000 @ bl if these bits are set
diff --git a/arch/arm/lib/backtrace.S b/arch/arm/lib/backtrace.S
index 582925238d65..872f658638d9 100644
--- a/arch/arm/lib/backtrace.S
+++ b/arch/arm/lib/backtrace.S
@@ -18,6 +18,7 @@
#define sv_pc r6
#define mask r7
#define offset r8
+#define loglvl r9
ENTRY(c_backtrace)
@@ -25,9 +26,10 @@ ENTRY(c_backtrace)
ret lr
ENDPROC(c_backtrace)
#else
- stmfd sp!, {r4 - r8, lr} @ Save an extra register so we have a location...
+ stmfd sp!, {r4 - r9, lr} @ Save an extra register so we have a location...
movs frame, r0 @ if frame pointer is zero
beq no_frame @ we have no stack frames
+ mov loglvl, r2
tst r1, #0x10 @ 26 or 32-bit mode?
ARM( moveq mask, #0xfc000003 )
@@ -73,6 +75,7 @@ for_each_frame: tst frame, mask @ Check for address exceptions
ldr r1, [frame, #-4] @ get saved lr
mov r2, frame
bic r1, r1, mask @ mask PC/LR for the mode
+ mov r3, loglvl
bl dump_backtrace_entry
ldr r1, [sv_pc, #-4] @ if stmfd sp!, {args} exists,
@@ -80,12 +83,14 @@ for_each_frame: tst frame, mask @ Check for address exceptions
teq r3, r1, lsr #11
ldreq r0, [frame, #-8] @ get sp
subeq r0, r0, #4 @ point at the last arg
+ mov r2, loglvl
bleq dump_backtrace_stm @ dump saved registers
1004: ldr r1, [sv_pc, #0] @ if stmfd sp!, {..., fp, ip, lr, pc}
ldr r3, .Ldsi @ instruction exists,
teq r3, r1, lsr #11
subeq r0, frame, #16
+ mov r2, loglvl
bleq dump_backtrace_stm @ dump saved registers
teq sv_fp, #0 @ zero saved fp means
@@ -96,9 +101,10 @@ for_each_frame: tst frame, mask @ Check for address exceptions
bhi for_each_frame
1006: adr r0, .Lbad
- mov r1, frame
+ mov r1, loglvl
+ mov r2, frame
bl printk
-no_frame: ldmfd sp!, {r4 - r8, pc}
+no_frame: ldmfd sp!, {r4 - r9, pc}
ENDPROC(c_backtrace)
.pushsection __ex_table,"a"
@@ -109,7 +115,7 @@ ENDPROC(c_backtrace)
.long 1004b, 1006b
.popsection
-.Lbad: .asciz "Backtrace aborted due to bad frame pointer <%p>\n"
+.Lbad: .asciz "%sBacktrace aborted due to bad frame pointer <%p>\n"
.align
.Ldsi: .word 0xe92dd800 >> 11 @ stmfd sp!, {... fp, ip, lr, pc}
.word 0xe92d0000 >> 11 @ stmfd sp!, {}